refactor(3p/nix/libstore): Replace logging.h with glog r/756

25 files changed, 514 insertions, 464 deletions

diff --git a/third_party/nix/src/libstore/binary-cache-store.cc b/third_party/nix/src/libstore/binary-cache-store.cc
index a601ef77a3..a9e7057648 100644
--- a/third_party/nix/src/libstore/binary-cache-store.cc
+++ b/third_party/nix/src/libstore/binary-cache-store.cc
@@ -6,6 +6,7 @@
 #include "derivations.hh"
 #include "fs-accessor.hh"
 #include "globals.hh"
+#include "glog/logging.h"
 #include "json.hh"
 #include "nar-accessor.hh"
 #include "nar-info-disk-cache.hh"
@@ -176,12 +177,10 @@ void BinaryCacheStore::addToStore(const ValidPathInfo& info,
   auto duration =
       std::chrono::duration_cast<std::chrono::milliseconds>(now2 - now1)
           .count();
-  printMsg(lvlTalkative,
-           format("copying path '%1%' (%2% bytes, compressed %3$.1f%% in %4% "
-                  "ms) to binary cache") %
-               narInfo->path % narInfo->narSize %
-               ((1.0 - (double)narCompressed->size() / nar->size()) * 100.0) %
-               duration);
+  DLOG(INFO) << "copying path '" << narInfo->path << "' (" << narInfo->narSize
+             << " bytes, compressed "
+             << ((1.0 - (double)narCompressed->size() / nar->size()) * 100.0)
+             << "% in " << duration << "ms) to binary cache";
 
   /* Atomically write the NAR file. */
   narInfo->url = "nar/" + narInfo->fileHash.to_string(Base32, false) + ".nar" +
@@ -243,35 +242,28 @@ void BinaryCacheStore::queryPathInfoUncached(
     const Path& storePath,
     Callback<std::shared_ptr<ValidPathInfo>> callback) noexcept {
   auto uri = getUri();
-  auto act = std::make_shared<Activity>(
-      *logger, lvlTalkative, actQueryPathInfo,
-      fmt("querying info about '%s' on '%s'", storePath, uri),
-      Logger::Fields{storePath, uri});
-  PushActivity pact(act->id);
+  LOG(INFO) << "querying info about '" << storePath << "' on '" << uri << "'";
 
   auto narInfoFile = narInfoFileFor(storePath);
 
   auto callbackPtr = std::make_shared<decltype(callback)>(std::move(callback));
 
-  getFile(
-      narInfoFile, {[=](std::future<std::shared_ptr<std::string>> fut) {
-        try {
-          auto data = fut.get();
+  getFile(narInfoFile, {[=](std::future<std::shared_ptr<std::string>> fut) {
+            try {
+              auto data = fut.get();
 
-          if (!data) return (*callbackPtr)(nullptr);
+              if (!data) return (*callbackPtr)(nullptr);
 
-          stats.narInfoRead++;
+              stats.narInfoRead++;
 
-          (*callbackPtr)(
-              (std::shared_ptr<ValidPathInfo>)std::make_shared<NarInfo>(
-                  *this, *data, narInfoFile));
+              (*callbackPtr)(
+                  (std::shared_ptr<ValidPathInfo>)std::make_shared<NarInfo>(
+                      *this, *data, narInfoFile));
 
-          (void)
-              act;  // force Activity into this lambda to ensure it stays alive
-        } catch (...) {
-          callbackPtr->rethrow();
-        }
-      }});
+            } catch (...) {
+              callbackPtr->rethrow();
+            }
+          }});
 }
 
 Path BinaryCacheStore::addToStore(const string& name, const Path& srcPath,
@@ -356,7 +348,8 @@ std::shared_ptr<std::string> BinaryCacheStore::getBuildLog(const Path& path) {
 
   auto logPath = "log/" + baseNameOf(drvPath);
 
-  debug("fetching build log from binary cache '%s/%s'", getUri(), logPath);
+  DLOG(INFO) << "fetching build log from binary cache '" << getUri() << "/"
+             << logPath << "'";
 
   return getFile(logPath);
 }
diff --git a/third_party/nix/src/libstore/build.cc b/third_party/nix/src/libstore/build.cc
index c110bd4e6e..c9acb4dfb4 100644
--- a/third_party/nix/src/libstore/build.cc
+++ b/third_party/nix/src/libstore/build.cc
@@ -31,6 +31,7 @@
 #include "download.hh"
 #include "finally.hh"
 #include "globals.hh"
+#include "glog/logging.h"
 #include "json.hh"
 #include "local-store.hh"
 #include "machines.hh"
@@ -226,10 +227,6 @@ class Worker {
   std::map<Path, bool> pathContentsGoodCache;
 
  public:
-  const Activity act;
-  const Activity actDerivations;
-  const Activity actSubstitutions;
-
   /* Set if at least one derivation had a BuildError (i.e. permanent
      failure). */
   bool permanentFailure;
@@ -327,16 +324,6 @@ class Worker {
   bool pathContentsGood(const Path& path);
 
   void markContentsGood(const Path& path);
-
-  void updateProgress() {
-    actDerivations.progress(doneBuilds, expectedBuilds + doneBuilds,
-                            runningBuilds, failedBuilds);
-    actSubstitutions.progress(doneSubstitutions,
-                              expectedSubstitutions + doneSubstitutions,
-                              runningSubstitutions, failedSubstitutions);
-    act.setExpected(actDownload, expectedDownloadSize + doneDownloadSize);
-    act.setExpected(actCopyPath, expectedNarSize + doneNarSize);
-  }
 };
 
 //////////////////////////////////////////////////////////////////////
@@ -397,7 +384,9 @@ void Goal::amDone(ExitCode result) {
   worker.removeGoal(shared_from_this());
 }
 
-void Goal::trace(const FormatOrString& fs) { debug("%1%: %2%", name, fs.s); }
+void Goal::trace(const FormatOrString& fs) {
+  DLOG(INFO) << name << ": " << fs.s;
+}
 
 //////////////////////////////////////////////////////////////////////
 
@@ -445,9 +434,11 @@ void handleDiffHook(uid_t uid, uid_t gid, Path tryA, Path tryB, Path drvPath,
                         fmt("diff-hook program '%1%' %2%", diffHook,
                             statusToString(diffRes.first)));
 
-      if (diffRes.second != "") printError(chomp(diffRes.second));
+      if (diffRes.second != "") {
+        LOG(ERROR) << chomp(diffRes.second);
+      }
     } catch (Error& error) {
-      printError("diff hook execution failed: %s", error.what());
+      LOG(ERROR) << "diff hook execution failed: " << error.what();
     }
   }
 }
@@ -507,7 +498,7 @@ UserLock::UserLock() {
   /* Copy the result of getgrnam. */
   Strings users;
   for (char** p = gr->gr_mem; *p; ++p) {
-    debug(format("found build user '%1%'") % *p);
+    DLOG(INFO) << "found build user " << *p;
     users.push_back(*p);
   }
 
@@ -518,7 +509,7 @@ UserLock::UserLock() {
   /* Find a user account that isn't currently in use for another
      build. */
   for (auto& i : users) {
-    debug(format("trying user '%1%'") % i);
+    DLOG(INFO) << "trying user " << i;
 
     struct passwd* pw = getpwnam(i.c_str());
     if (!pw)
@@ -607,15 +598,13 @@ struct HookInstance {
 
   FdSink sink;
 
-  std::map<ActivityId, Activity> activities;
-
   HookInstance();
 
   ~HookInstance();
 };
 
 HookInstance::HookInstance() {
-  debug("starting build hook '%s'", settings.buildHook);
+  DLOG(INFO) << "starting build hook " << settings.buildHook;
 
   /* Create a pipe to get the output of the child. */
   fromHook.create();
@@ -630,24 +619,29 @@ HookInstance::HookInstance() {
   pid = startProcess([&]() {
     commonChildInit(fromHook);
 
-    if (chdir("/") == -1) throw SysError("changing into /");
+    if (chdir("/") == -1) {
+      throw SysError("changing into /");
+    }
 
     /* Dup the communication pipes. */
-    if (dup2(toHook.readSide.get(), STDIN_FILENO) == -1)
+    if (dup2(toHook.readSide.get(), STDIN_FILENO) == -1) {
       throw SysError("dupping to-hook read side");
+    }
 
     /* Use fd 4 for the builder's stdout/stderr. */
-    if (dup2(builderOut.writeSide.get(), 4) == -1)
+    if (dup2(builderOut.writeSide.get(), 4) == -1) {
       throw SysError("dupping builder's stdout/stderr");
+    }
 
     /* Hack: pass the read side of that fd to allow build-remote
        to read SSH error messages. */
-    if (dup2(builderOut.readSide.get(), 5) == -1)
+    if (dup2(builderOut.readSide.get(), 5) == -1) {
       throw SysError("dupping builder's stdout/stderr");
+    }
 
     Strings args = {
         baseNameOf(settings.buildHook),
-        std::to_string(verbosity),
+        // std::to_string(verbosity), // TODO(tazjin): what?
     };
 
     execv(settings.buildHook.get().c_str(), stringsToCharPtrs(args).data());
@@ -842,10 +836,6 @@ class DerivationGoal : public Goal {
 
   std::unique_ptr<MaintainCount<uint64_t>> mcExpectedBuilds, mcRunningBuilds;
 
-  std::unique_ptr<Activity> act;
-
-  std::map<ActivityId, Activity> builderActivities;
-
   /* The remote machine on which we're building. */
   std::string machineName;
 
@@ -972,7 +962,6 @@ DerivationGoal::DerivationGoal(const Path& drvPath,
 
   mcExpectedBuilds =
       std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds);
-  worker.updateProgress();
 }
 
 DerivationGoal::DerivationGoal(const Path& drvPath, const BasicDerivation& drv,
@@ -988,7 +977,6 @@ DerivationGoal::DerivationGoal(const Path& drvPath, const BasicDerivation& drv,
 
   mcExpectedBuilds =
       std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds);
-  worker.updateProgress();
 
   /* Prevent the .chroot directory from being
      garbage-collected. (See isActiveTempFile() in gc.cc.) */
@@ -1089,7 +1077,7 @@ void DerivationGoal::loadDerivation() {
   trace("loading derivation");
 
   if (nrFailed != 0) {
-    printError(format("cannot build missing derivation '%1%'") % drvPath);
+    LOG(ERROR) << "cannot build missing derivation '" << drvPath << "'";
     done(BuildResult::MiscFailure);
     return;
   }
@@ -1241,9 +1229,8 @@ void DerivationGoal::repairClosure() {
   PathSet broken;
   for (auto& i : outputClosure) {
     if (worker.pathContentsGood(i)) continue;
-    printError(format("found corrupted or missing path '%1%' in the output "
-                      "closure of '%2%'") %
-               i % drvPath);
+    LOG(ERROR) << "found corrupted or missing path '" << i
+               << "' in the output closure of '" << drvPath << "'";
     Path drvPath2 = outputsToDrv[i];
     if (drvPath2 == "")
       addWaitee(worker.makeSubstitutionGoal(i, Repair));
@@ -1274,9 +1261,8 @@ void DerivationGoal::inputsRealised() {
   if (nrFailed != 0) {
     if (!useDerivation)
       throw Error(format("some dependencies of '%1%' are missing") % drvPath);
-    printError(format("cannot build derivation '%1%': %2% dependencies "
-                      "couldn't be built") %
-               drvPath % nrFailed);
+    LOG(ERROR) << "cannot build derivation '" << drvPath << "': " << nrFailed
+               << " dependencies couldn't be built";
     done(BuildResult::DependencyFailed);
     return;
   }
@@ -1291,7 +1277,7 @@ void DerivationGoal::inputsRealised() {
 
   /* The outputs are referenceable paths. */
   for (auto& i : drv->outputs) {
-    debug(format("building path '%1%'") % i.second.path);
+    DLOG(INFO) << "building path " << i.second.path;
     allPaths.insert(i.second.path);
   }
 
@@ -1317,7 +1303,7 @@ void DerivationGoal::inputsRealised() {
   /* Second, the input sources. */
   worker.store.computeFSClosure(drv->inputSrcs, inputPaths);
 
-  debug(format("added input paths %1%") % showPaths(inputPaths));
+  DLOG(INFO) << "added input paths " << showPaths(inputPaths);
 
   allPaths.insert(inputPaths.begin(), inputPaths.end());
 
@@ -1363,8 +1349,8 @@ void DerivationGoal::tryToBuild() {
      build this derivation, so no further checks are necessary. */
   validPaths = checkPathValidity(true, buildMode == bmRepair);
   if (buildMode != bmCheck && validPaths.size() == drv->outputs.size()) {
-    debug(format("skipping build of derivation '%1%', someone beat us to it") %
-          drvPath);
+    DLOG(INFO) << "skipping build of derivation '" << drvPath
+               << "', someone beat us to it";
     outputLocks.setDeletion(true);
     done(BuildResult::AlreadyValid);
     return;
@@ -1379,7 +1365,7 @@ void DerivationGoal::tryToBuild() {
   for (auto& i : drv->outputs) {
     Path path = i.second.path;
     if (worker.store.isValidPath(path)) continue;
-    debug(format("removing invalid path '%1%'") % path);
+    DLOG(INFO) << "removing invalid path " << path;
     deletePath(worker.store.toRealPath(path));
   }
 
@@ -1396,14 +1382,13 @@ void DerivationGoal::tryToBuild() {
                              : nrRounds > 1 ? "building '%s' (round %d/%d)"
                                             : "building '%s'",
                    drvPath, curRound, nrRounds);
-    fmt("building '%s'", drvPath);
-    if (hook) msg += fmt(" on '%s'", machineName);
-    act = std::make_unique<Activity>(
-        *logger, lvlInfo, actBuild, msg,
-        Logger::Fields{drvPath, hook ? machineName : "", curRound, nrRounds});
+
+    if (hook) {
+      msg += fmt(" on '%s'", machineName);
+    }
+    LOG(INFO) << msg << "[" << drvPath << "]";
     mcRunningBuilds =
         std::make_unique<MaintainCount<uint64_t>>(worker.runningBuilds);
-    worker.updateProgress();
   };
 
   /* Is the build hook willing to accept this job? */
@@ -1443,7 +1428,7 @@ void DerivationGoal::tryToBuild() {
     startBuilder();
 
   } catch (BuildError& e) {
-    printError(e.msg());
+    LOG(ERROR) << e.msg();
     outputLocks.unlock();
     buildUser.reset();
     worker.permanentFailure = true;
@@ -1487,7 +1472,7 @@ MakeError(NotDeterministic, BuildError)
      kill it. */
   int status = hook ? hook->pid.kill() : pid.kill();
 
-  debug(format("builder process for '%1%' finished") % drvPath);
+  DLOG(INFO) << "builder process for '" << drvPath << "' finished";
 
   result.timesBuilt++;
   result.stopTime = time(0);
@@ -1552,10 +1537,11 @@ MakeError(NotDeterministic, BuildError)
         for (auto& line : logTail) msg += "\n  " + line;
       }
 
-      if (diskFull)
+      if (diskFull) {
         msg +=
             "\nnote: build failure may have been caused by lack of free disk "
             "space";
+      }
 
       throw BuildError(msg);
     }
@@ -1565,10 +1551,8 @@ MakeError(NotDeterministic, BuildError)
     registerOutputs();
 
     if (settings.postBuildHook != "") {
-      Activity act(*logger, lvlInfo, actPostBuildHook,
-                   fmt("running post-build-hook '%s'", settings.postBuildHook),
-                   Logger::Fields{drvPath});
-      PushActivity pact(act.id);
+      LOG(INFO) << "running post-build-hook '" << settings.postBuildHook
+                << "' [" << drvPath << "]";
       auto outputPaths = drv->outputPaths();
       std::map<std::string, std::string> hookEnvironment = getEnv();
 
@@ -1580,11 +1564,8 @@ MakeError(NotDeterministic, BuildError)
       opts.environment = hookEnvironment;
 
       struct LogSink : Sink {
-        Activity& act;
         std::string currentLine;
 
-        LogSink(Activity& act) : act(act) {}
-
         void operator()(const unsigned char* data, size_t len) override {
           for (size_t i = 0; i < len; i++) {
             auto c = data[i];
@@ -1599,9 +1580,7 @@ MakeError(NotDeterministic, BuildError)
 
         void flushLine() {
           if (settings.verboseBuild) {
-            printError("post-build-hook: " + currentLine);
-          } else {
-            act.result(resPostBuildLogLine, currentLine);
+            LOG(ERROR) << "post-build-hook: " << currentLine;
           }
           currentLine.clear();
         }
@@ -1613,7 +1592,7 @@ MakeError(NotDeterministic, BuildError)
           }
         }
       };
-      LogSink sink(act);
+      LogSink sink;
 
       opts.standardOut = &sink;
       opts.mergeStderrToStdout = true;
@@ -1649,7 +1628,7 @@ MakeError(NotDeterministic, BuildError)
     outputLocks.unlock();
 
   } catch (BuildError& e) {
-    printError(e.msg());
+    LOG(ERROR) << e.msg();
 
     outputLocks.unlock();
 
@@ -1696,38 +1675,37 @@ HookReply DerivationGoal::tryBuildHook() {
     string reply;
     while (true) {
       string s = readLine(worker.hook->fromHook.readSide.get());
-      if (handleJSONLogMessage(s, worker.act, worker.hook->activities, true))
-        ;
-      else if (string(s, 0, 2) == "# ") {
+      if (string(s, 0, 2) == "# ") {
         reply = string(s, 2);
         break;
       } else {
         s += "\n";
-        writeToStderr(s);
+        std::cerr << s;
       }
     }
 
-    debug(format("hook reply is '%1%'") % reply);
+    DLOG(INFO) << "hook reply is " << reply;
 
-    if (reply == "decline")
+    if (reply == "decline") {
       return rpDecline;
-    else if (reply == "decline-permanently") {
+    } else if (reply == "decline-permanently") {
       worker.tryBuildHook = false;
       worker.hook = 0;
       return rpDecline;
-    } else if (reply == "postpone")
+    } else if (reply == "postpone") {
       return rpPostpone;
-    else if (reply != "accept")
+    } else if (reply != "accept") {
       throw Error(format("bad hook reply '%1%'") % reply);
-
+    }
   } catch (SysError& e) {
     if (e.errNo == EPIPE) {
-      printError("build hook died unexpectedly: %s",
-                 chomp(drainFD(worker.hook->fromHook.readSide.get())));
+      LOG(ERROR) << "build hook died unexpectedly: "
+                 << chomp(drainFD(worker.hook->fromHook.readSide.get()));
       worker.hook = 0;
       return rpDecline;
-    } else
+    } else {
       throw;
+    }
   }
 
   hook = std::move(worker.hook);
@@ -2007,8 +1985,7 @@ void DerivationGoal::startBuilder() {
     /* Clean up the chroot directory automatically. */
     autoDelChroot = std::make_shared<AutoDelete>(chrootRootDir);
 
-    printMsg(lvlChatty,
-             format("setting up chroot environment in '%1%'") % chrootRootDir);
+    DLOG(INFO) << "setting up chroot environment in '" << chrootRootDir << "'";
 
     if (mkdir(chrootRootDir.c_str(), 0750) == -1)
       throw SysError(format("cannot create '%1%'") % chrootRootDir);
@@ -2073,7 +2050,7 @@ void DerivationGoal::startBuilder() {
         dirsInChroot[i] = r;
       else {
         Path p = chrootRootDir + i;
-        debug("linking '%1%' to '%2%'", p, r);
+        DLOG(INFO) << "linking '" << p << "' to '" << r << "'";
         if (link(r.c_str(), p.c_str()) == -1) {
           /* Hard-linking fails if we exceed the maximum
              link count on a file (e.g. 32000 of ext3),
@@ -2132,8 +2109,7 @@ void DerivationGoal::startBuilder() {
 
   if (useChroot && settings.preBuildHook != "" &&
       dynamic_cast<Derivation*>(drv.get())) {
-    printMsg(lvlChatty,
-             format("executing pre-build hook '%1%'") % settings.preBuildHook);
+    DLOG(INFO) << "executing pre-build hook '" << settings.preBuildHook << "'";
     auto args =
         useChroot ? Strings({drvPath, chrootRootDir}) : Strings({drvPath});
     enum BuildHookState { stBegin, stExtraChrootDirs };
@@ -2165,7 +2141,7 @@ void DerivationGoal::startBuilder() {
   }
 
   /* Run the builder. */
-  printMsg(lvlChatty, format("executing builder '%1%'") % drv->builder);
+  DLOG(INFO) << "executing builder '" << drv->builder << "'";
 
   /* Create the log file. */
   Path logFile = openLogFile();
@@ -2364,7 +2340,7 @@ void DerivationGoal::startBuilder() {
       if (msg.size() == 1) break;
       throw Error(string(msg, 1));
     }
-    debug(msg);
+    DLOG(INFO) << msg;
   }
 }
 
@@ -2604,10 +2580,10 @@ void setupSeccomp() {
     throw SysError("unable to add X32 seccomp architecture");
 
   if (nativeSystem == "aarch64-linux" &&
-      seccomp_arch_add(ctx, SCMP_ARCH_ARM) != 0)
-    printError(
-        "unable to add ARM seccomp architecture; this may result in spurious "
-        "build failures if running 32-bit ARM processes");
+      seccomp_arch_add(ctx, SCMP_ARCH_ARM) != 0) {
+    LOG(ERROR) << "unable to add ARM seccomp architecture; this may result in "
+               << "spurious build failures if running 32-bit ARM processes";
+  }
 
   /* Prevent builders from creating setuid/setgid binaries. */
   for (int perm : {S_ISUID, S_ISGID}) {
@@ -2772,7 +2748,7 @@ void DerivationGoal::runChild() {
          environment. */
       auto doBind = [&](const Path& source, const Path& target,
                         bool optional = false) {
-        debug(format("bind mounting '%1%' to '%2%'") % source % target);
+        DLOG(INFO) << "bind mounting '" << source << "' to '" << target << "'";
         struct stat st;
         if (stat(source.c_str(), &st) == -1) {
           if (optional && errno == ENOENT)
@@ -3082,8 +3058,6 @@ void DerivationGoal::runChild() {
     /* Execute the program.  This should not return. */
     if (drv->isBuiltin()) {
       try {
-        logger = makeJSONLogger(*logger);
-
         BasicDerivation drv2(*drv);
         for (auto& e : drv2.env)
           e.second = rewriteStrings(e.second, inputRewrites);
@@ -3215,8 +3189,7 @@ void DerivationGoal::registerOutputs() {
     /* Apply hash rewriting if necessary. */
     bool rewritten = false;
     if (!outputRewrites.empty()) {
-      printError(format("warning: rewriting hashes in '%1%'; cross fingers") %
-                 path);
+      LOG(WARNING) << "rewriting hashes in '" << path << "'; cross fingers";
 
       /* Canonicalise first.  This ensures that the path we're
          rewriting doesn't contain a hard link to /etc/shadow or
@@ -3300,7 +3273,7 @@ void DerivationGoal::registerOutputs() {
        contained in it.  Compute the SHA-256 NAR hash at the same
        time.  The hash is stored in the database so that we can
        verify later on whether nobody has messed with the store. */
-    debug("scanning for references inside '%1%'", path);
+    DLOG(INFO) << "scanning for references inside '" << path << "'";
     HashResult hash;
     PathSet references = scanForReferences(actualPath, allPaths, hash);
 
@@ -3346,9 +3319,9 @@ void DerivationGoal::registerOutputs() {
     for (auto& i : inputPaths) {
       PathSet::iterator j = references.find(i);
       if (j == references.end())
-        debug(format("unreferenced input: '%1%'") % i);
+        DLOG(INFO) << "unreferenced input: '" << i << "'";
       else
-        debug(format("referenced input: '%1%'") % i);
+        DLOG(INFO) << "referenced input: '" << i << "'";
     }
 
     if (curRound == nrRounds) {
@@ -3397,9 +3370,11 @@ void DerivationGoal::registerOutputs() {
                        buildUser ? buildUser->getGID() : getgid(), prev,
                        i->second.path, drvPath, tmpDir);
 
-        if (settings.enforceDeterminism) throw NotDeterministic(msg);
+        if (settings.enforceDeterminism) {
+          throw NotDeterministic(msg);
+        }
 
-        printError(msg);
+        LOG(ERROR) << msg;
         curRound = nrRounds;  // we know enough, bail out early
       }
   }
@@ -3644,8 +3619,7 @@ void DerivationGoal::deleteTmpDir(bool force) {
     /* Don't keep temporary directories for builtins because they
        might have privileged stuff (like a copy of netrc). */
     if (settings.keepFailed && !force && !drv->isBuiltin()) {
-      printError(format("note: keeping build directory '%2%'") % drvPath %
-                 tmpDir);
+      LOG(INFO) << "note: keeping build directory '" << tmpDir << "'";
       chmod(tmpDir.c_str(), 0755);
     } else
       deletePath(tmpDir);
@@ -3658,20 +3632,20 @@ void DerivationGoal::handleChildOutput(int fd, const string& data) {
       (!hook && fd == builderOut.readSide.get())) {
     logSize += data.size();
     if (settings.maxLogSize && logSize > settings.maxLogSize) {
-      printError(
-          format("%1% killed after writing more than %2% bytes of log output") %
-          getName() % settings.maxLogSize);
+      LOG(ERROR) << getName()
+                 << " killed after writing more than %2% bytes of log output"
+                 << settings.maxLogSize;
       killChild();
       done(BuildResult::LogLimitExceeded);
       return;
     }
 
     for (auto c : data)
-      if (c == '\r')
+      if (c == '\r') {
         currentLogLinePos = 0;
-      else if (c == '\n')
+      } else if (c == '\n') {
         flushLine();
-      else {
+      } else {
         if (currentLogLinePos >= currentLogLine.size())
           currentLogLine.resize(currentLogLinePos + 1);
         currentLogLine[currentLogLinePos++] = c;
@@ -3683,11 +3657,10 @@ void DerivationGoal::handleChildOutput(int fd, const string& data) {
   if (hook && fd == hook->fromHook.readSide.get()) {
     for (auto c : data)
       if (c == '\n') {
-        handleJSONLogMessage(currentHookLine, worker.act, hook->activities,
-                             true);
         currentHookLine.clear();
-      } else
+      } else {
         currentHookLine += c;
+      }
   }
 }
 
@@ -3697,19 +3670,11 @@ void DerivationGoal::handleEOF(int fd) {
 }
 
 void DerivationGoal::flushLine() {
-  if (handleJSONLogMessage(currentLogLine, *act, builderActivities, false))
-    ;
-
+  if (settings.verboseBuild && (settings.printRepeatedBuilds || curRound == 1))
+    LOG(INFO) << currentLogLine;
   else {
-    if (settings.verboseBuild &&
-        (settings.printRepeatedBuilds || curRound == 1))
-      printError(currentLogLine);
-    else {
-      logTail.push_back(currentLogLine);
-      if (logTail.size() > settings.logLines) logTail.pop_front();
-    }
-
-    act->result(resBuildLogLine, currentLogLine);
+    logTail.push_back(currentLogLine);
+    if (logTail.size() > settings.logLines) logTail.pop_front();
   }
 
   currentLogLine = "";
@@ -3719,10 +3684,14 @@ void DerivationGoal::flushLine() {
 PathSet DerivationGoal::checkPathValidity(bool returnValid, bool checkHash) {
   PathSet result;
   for (auto& i : drv->outputs) {
-    if (!wantOutput(i.first, wantedOutputs)) continue;
+    if (!wantOutput(i.first, wantedOutputs)) {
+      continue;
+    }
     bool good = worker.store.isValidPath(i.second.path) &&
                 (!checkHash || worker.pathContentsGood(i.second.path));
-    if (good == returnValid) result.insert(i.second.path);
+    if (good == returnValid) {
+      result.insert(i.second.path);
+    }
   }
   return result;
 }
@@ -3758,8 +3727,6 @@ void DerivationGoal::done(BuildResult::Status status, const string& msg) {
   } else {
     if (status != BuildResult::DependencyFailed) worker.failedBuilds++;
   }
-
-  worker.updateProgress();
 }
 
 //////////////////////////////////////////////////////////////////////
@@ -3891,9 +3858,9 @@ void SubstitutionGoal::tryNext() {
   if (subs.size() == 0) {
     /* None left.  Terminate this goal and let someone else deal
        with it. */
-    debug(format("path '%1%' is required, but there is no substituter that can "
-                 "build it") %
-          storePath);
+    DLOG(WARNING)
+        << "path '" << storePath
+        << "' is required, but there is no substituter that can build it";
 
     /* Hack: don't indicate failure if there were no substituters.
        In that case the calling derivation should just do a
@@ -3902,7 +3869,6 @@ void SubstitutionGoal::tryNext() {
 
     if (substituterFailed) {
       worker.failedSubstitutions++;
-      worker.updateProgress();
     }
 
     return;
@@ -3930,7 +3896,7 @@ void SubstitutionGoal::tryNext() {
     throw;
   } catch (Error& e) {
     if (settings.tryFallback) {
-      printError(e.what());
+      LOG(ERROR) << e.what();
       tryNext();
       return;
     }
@@ -3949,17 +3915,14 @@ void SubstitutionGoal::tryNext() {
                 worker.expectedDownloadSize, narInfo->fileSize)
           : nullptr;
 
-  worker.updateProgress();
-
   /* Bail out early if this substituter lacks a valid
      signature. LocalStore::addToStore() also checks for this, but
      only after we've downloaded the path. */
   if (worker.store.requireSigs && !sub->isTrusted &&
       !info->checkSignatures(worker.store, worker.store.getPublicKeys())) {
-    printError(
-        "warning: substituter '%s' does not have a valid signature for path "
-        "'%s'",
-        sub->getUri(), storePath);
+    LOG(WARNING) << "substituter '" << sub->getUri()
+                 << "' does not have a valid signature for path '" << storePath
+                 << "'";
     tryNext();
     return;
   }
@@ -3980,8 +3943,8 @@ void SubstitutionGoal::referencesValid() {
   trace("all references realised");
 
   if (nrFailed > 0) {
-    debug(format("some references of path '%1%' could not be realised") %
-          storePath);
+    DLOG(WARNING) << "some references of path '" << storePath
+                  << "' could not be realised";
     amDone(nrNoSubstituters > 0 || nrIncompleteClosure > 0 ? ecIncompleteClosure
                                                            : ecFailed);
     return;
@@ -4010,7 +3973,6 @@ void SubstitutionGoal::tryToRun() {
 
   maintainRunningSubstitutions =
       std::make_unique<MaintainCount<uint64_t>>(worker.runningSubstitutions);
-  worker.updateProgress();
 
   outPipe.create();
 
@@ -4021,10 +3983,6 @@ void SubstitutionGoal::tryToRun() {
       /* Wake up the worker loop when we're done. */
       Finally updateStats([this]() { outPipe.writeSide = -1; });
 
-      Activity act(*logger, actSubstitute,
-                   Logger::Fields{storePath, sub->getUri()});
-      PushActivity pact(act.id);
-
       copyStorePath(ref<Store>(sub),
                     ref<Store>(worker.store.shared_from_this()), storePath,
                     repair, sub->isTrusted ? NoCheckSigs : CheckSigs);
@@ -4050,7 +4008,7 @@ void SubstitutionGoal::finished() {
   try {
     promise.get_future().get();
   } catch (std::exception& e) {
-    printError(e.what());
+    LOG(ERROR) << e.what();
 
     /* Cause the parent build to fail unless --fallback is given,
        or the substitute has disappeared. The latter case behaves
@@ -4071,8 +4029,7 @@ void SubstitutionGoal::finished() {
 
   worker.markContentsGood(storePath);
 
-  printMsg(lvlChatty,
-           format("substitution of path '%1%' succeeded") % storePath);
+  DLOG(INFO) << "substitution of path '" << storePath << "' succeeded";
 
   maintainRunningSubstitutions.reset();
 
@@ -4088,8 +4045,6 @@ void SubstitutionGoal::finished() {
   worker.doneNarSize += maintainExpectedNar->delta;
   maintainExpectedNar.reset();
 
-  worker.updateProgress();
-
   amDone(ecSuccess);
 }
 
@@ -4103,11 +4058,7 @@ void SubstitutionGoal::handleEOF(int fd) {
 
 static bool working = false;
 
-Worker::Worker(LocalStore& store)
-    : act(*logger, actRealise),
-      actDerivations(*logger, actBuilds),
-      actSubstitutions(*logger, actCopyPaths),
-      store(store) {
+Worker::Worker(LocalStore& store) : store(store) {
   /* Debugging: prevent recursive workers. */
   if (working) abort();
   working = true;
@@ -4242,7 +4193,7 @@ void Worker::childTerminated(Goal* goal, bool wakeSleepers) {
 }
 
 void Worker::waitForBuildSlot(GoalPtr goal) {
-  debug("wait for build slot");
+  DLOG(INFO) << "wait for build slot";
   if (getNrLocalBuilds() < settings.maxBuildJobs)
     wakeUp(goal); /* we can do it right away */
   else
@@ -4250,19 +4201,19 @@ void Worker::waitForBuildSlot(GoalPtr goal) {
 }
 
 void Worker::waitForAnyGoal(GoalPtr goal) {
-  debug("wait for any goal");
+  DLOG(INFO) << "wait for any goal";
   addToWeakGoals(waitingForAnyGoal, goal);
 }
 
 void Worker::waitForAWhile(GoalPtr goal) {
-  debug("wait for a while");
+  DLOG(INFO) << "wait for a while";
   addToWeakGoals(waitingForAWhile, goal);
 }
 
 void Worker::run(const Goals& _topGoals) {
   for (auto& i : _topGoals) topGoals.insert(i);
 
-  debug("entered goal loop");
+  DLOG(INFO) << "entered goal loop";
 
   while (1) {
     checkInterrupt();
@@ -4308,7 +4259,7 @@ void Worker::run(const Goals& _topGoals) {
 }
 
 void Worker::waitForInput() {
-  printMsg(lvlVomit, "waiting for children");
+  DLOG(INFO) << "waiting for children";
 
   /* Process output from the file descriptors attached to the
      children, namely log output and output path creation commands.
@@ -4350,7 +4301,7 @@ void Worker::waitForInput() {
   if (!waitingForAWhile.empty()) {
     useTimeout = true;
     if (lastWokenUp == steady_time_point::min())
-      printError("waiting for locks or build slots...");
+      DLOG(WARNING) << "waiting for locks or build slots...";
     if (lastWokenUp == steady_time_point::min() || lastWokenUp > before)
       lastWokenUp = before;
     timeout.tv_sec = std::max(
@@ -4361,7 +4312,9 @@ void Worker::waitForInput() {
   } else
     lastWokenUp = steady_time_point::min();
 
-  if (useTimeout) vomit("sleeping %d seconds", timeout.tv_sec);
+  if (useTimeout) {
+    DLOG(INFO) << "sleeping " << timeout.tv_sec << " seconds";
+  }
 
   /* Use select() to wait for the input side of any logger pipe to
      become `available'.  Note that `available' (i.e., non-blocking)
@@ -4403,15 +4356,14 @@ void Worker::waitForInput() {
         // FIXME: is there a cleaner way to handle pt close
         // than EIO? Is this even standard?
         if (rd == 0 || (rd == -1 && errno == EIO)) {
-          debug(format("%1%: got EOF") % goal->getName());
+          DLOG(WARNING) << goal->getName() << ": got EOF";
           goal->handleEOF(k);
           j->fds.erase(k);
         } else if (rd == -1) {
           if (errno != EINTR)
             throw SysError("%s: read failed", goal->getName());
         } else {
-          printMsg(lvlVomit,
-                   format("%1%: read %2% bytes") % goal->getName() % rd);
+          DLOG(INFO) << goal->getName() << ": read " << rd << " bytes";
           string data((char*)buffer.data(), rd);
           j->lastOutput = after;
           goal->handleChildOutput(k, data);
@@ -4422,8 +4374,8 @@ void Worker::waitForInput() {
     if (goal->getExitCode() == Goal::ecBusy && 0 != settings.maxSilentTime &&
         j->respectTimeouts &&
         after - j->lastOutput >= std::chrono::seconds(settings.maxSilentTime)) {
-      printError(format("%1% timed out after %2% seconds of silence") %
-                 goal->getName() % settings.maxSilentTime);
+      LOG(ERROR) << goal->getName() << " timed out after "
+                 << settings.maxSilentTime << " seconds of silence";
       goal->timedOut();
     }
 
@@ -4431,8 +4383,8 @@ void Worker::waitForInput() {
              0 != settings.buildTimeout && j->respectTimeouts &&
              after - j->timeStarted >=
                  std::chrono::seconds(settings.buildTimeout)) {
-      printError(format("%1% timed out after %2% seconds") % goal->getName() %
-                 settings.buildTimeout);
+      LOG(ERROR) << goal->getName() << " timed out after "
+                 << settings.buildTimeout << " seconds";
       goal->timedOut();
     }
   }
@@ -4473,7 +4425,7 @@ unsigned int Worker::exitStatus() {
 bool Worker::pathContentsGood(const Path& path) {
   std::map<Path, bool>::iterator i = pathContentsGoodCache.find(path);
   if (i != pathContentsGoodCache.end()) return i->second;
-  printInfo(format("checking path '%1%'...") % path);
+  LOG(INFO) << "checking path '" << path << "'...";
   auto info = store.queryPathInfo(path);
   bool res;
   if (!pathExists(path))
@@ -4484,7 +4436,9 @@ bool Worker::pathContentsGood(const Path& path) {
     res = info->narHash == nullHash || info->narHash == current.first;
   }
   pathContentsGoodCache[path] = res;
-  if (!res) printError(format("path '%1%' is corrupted or missing!") % path);
+  if (!res) {
+    LOG(ERROR) << "path '" << path << "' is corrupted or missing!";
+  }
   return res;
 }
 
diff --git a/third_party/nix/src/libstore/builtins/buildenv.cc b/third_party/nix/src/libstore/builtins/buildenv.cc
index ce054a4303..68b2dd0f39 100644
--- a/third_party/nix/src/libstore/builtins/buildenv.cc
+++ b/third_party/nix/src/libstore/builtins/buildenv.cc
@@ -1,4 +1,5 @@
 #include <fcntl.h>
+#include <glog/logging.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <algorithm>
@@ -22,10 +23,8 @@ static void createLinks(const Path& srcDir, const Path& dstDir, int priority) {
     srcFiles = readDirectory(srcDir);
   } catch (SysError& e) {
     if (e.errNo == ENOTDIR) {
-      printError(
-          "warning: not including '%s' in the user environment because it's "
-          "not a directory",
-          srcDir);
+      LOG(ERROR) << "warning: not including '" << srcDir
+                 << "' in the user environment because it's not a directory";
       return;
     }
     throw;
@@ -43,7 +42,7 @@ static void createLinks(const Path& srcDir, const Path& dstDir, int priority) {
         throw SysError("getting status of '%1%'", srcFile);
     } catch (SysError& e) {
       if (e.errNo == ENOENT || e.errNo == ENOTDIR) {
-        printError("warning: skipping dangling symlink '%s'", dstFile);
+        LOG(ERROR) << "warning: skipping dangling symlink '" << dstFile << "'";
         continue;
       }
       throw;
@@ -200,7 +199,7 @@ void builtinBuildenv(const BasicDerivation& drv) {
     for (const auto& pkgDir : pkgDirs) addPkg(pkgDir, priorityCounter++);
   }
 
-  printError("created %d symlinks in user environment", symlinks);
+  LOG(INFO) << "created " << symlinks << " symlinks in user environment";
 
   createSymlink(getAttr("manifest"), out + "/manifest.nix");
 }
diff --git a/third_party/nix/src/libstore/builtins/fetchurl.cc b/third_party/nix/src/libstore/builtins/fetchurl.cc
index ae4e9a71c8..88acc413c9 100644
--- a/third_party/nix/src/libstore/builtins/fetchurl.cc
+++ b/third_party/nix/src/libstore/builtins/fetchurl.cc
@@ -1,3 +1,4 @@
+#include <glog/logging.h>
 #include "archive.hh"
 #include "builtins.hh"
 #include "compression.hh"
@@ -66,7 +67,7 @@ void builtinFetchurl(const BasicDerivation& drv, const std::string& netrcData) {
               h.to_string(Base16, false));
         return;
       } catch (Error& e) {
-        debug(e.what());
+        LOG(ERROR) << e.what();
       }
 
   /* Otherwise try the specified URL. */
diff --git a/third_party/nix/src/libstore/download.cc b/third_party/nix/src/libstore/download.cc
index 66d6cdd6cc..d84ac0c3cb 100644
--- a/third_party/nix/src/libstore/download.cc
+++ b/third_party/nix/src/libstore/download.cc
@@ -15,6 +15,7 @@
 
 #include <curl/curl.h>
 #include <fcntl.h>
+#include <glog/logging.h>
 #include <unistd.h>
 #include <algorithm>
 #include <cmath>
@@ -50,7 +51,6 @@ struct CurlDownloader : public Downloader {
     CurlDownloader& downloader;
     DownloadRequest request;
     DownloadResult result;
-    Activity act;
     bool done = false;  // whether either the success or failure function has
                         // been called
     Callback<DownloadResult> callback;
@@ -77,10 +77,6 @@ struct CurlDownloader : public Downloader {
                  Callback<DownloadResult>&& callback)
         : downloader(downloader),
           request(request),
-          act(*logger, lvlTalkative, actDownload,
-              fmt(request.data ? "uploading '%s'" : "downloading '%s'",
-                  request.uri),
-              {request.uri}, request.parentAct),
           callback(std::move(callback)),
           finalSink([this](const unsigned char* data, size_t len) {
             if (this->request.dataCallback) {
@@ -97,6 +93,9 @@ struct CurlDownloader : public Downloader {
             } else
               this->result.data->append((char*)data, len);
           }) {
+      LOG(INFO) << (request.data ? "uploading '" : "downloading '")
+                << request.uri << "'";
+
       if (!request.expectedETag.empty())
         requestHeaders = curl_slist_append(
             requestHeaders, ("If-None-Match: " + request.expectedETag).c_str());
@@ -162,8 +161,7 @@ struct CurlDownloader : public Downloader {
     size_t headerCallback(void* contents, size_t size, size_t nmemb) {
       size_t realSize = size * nmemb;
       std::string line((char*)contents, realSize);
-      printMsg(lvlVomit,
-               format("got header for '%s': %s") % request.uri % trim(line));
+      DLOG(INFO) << "got header for '" << request.uri << "': " << trim(line);
       if (line.compare(0, 5, "HTTP/") == 0) {  // new response starts
         result.etag = "";
         auto ss = tokenizeString<vector<string>>(line, " ");
@@ -184,8 +182,8 @@ struct CurlDownloader : public Downloader {
                down the connection because we already have the
                data. */
             if (result.etag == request.expectedETag && status == "200") {
-              debug(format(
-                  "shutting down on 200 HTTP response with expected ETag"));
+              DLOG(INFO)
+                  << "shutting down on 200 HTTP response with expected ETag";
               return 0;
             }
           } else if (name == "content-encoding")
@@ -205,7 +203,7 @@ struct CurlDownloader : public Downloader {
 
     int progressCallback(double dltotal, double dlnow) {
       try {
-        act.progress(dlnow, dltotal);
+        // TODO(tazjin): this had activity nonsense, clean it up
       } catch (nix::Interrupted&) {
         assert(_isInterrupted);
       }
@@ -220,8 +218,9 @@ struct CurlDownloader : public Downloader {
 
     static int debugCallback(CURL* handle, curl_infotype type, char* data,
                              size_t size, void* userptr) {
-      if (type == CURLINFO_TEXT)
-        vomit("curl: %s", chomp(std::string(data, size)));
+      if (type == CURLINFO_TEXT) {
+        DLOG(INFO) << "curl: " << chomp(std::string(data, size));
+      }
       return 0;
     }
 
@@ -245,11 +244,12 @@ struct CurlDownloader : public Downloader {
 
       curl_easy_reset(req);
 
-      if (verbosity >= lvlVomit) {
-        curl_easy_setopt(req, CURLOPT_VERBOSE, 1);
-        curl_easy_setopt(req, CURLOPT_DEBUGFUNCTION,
-                         DownloadItem::debugCallback);
-      }
+      // TODO(tazjin): Add an Abseil flag for this
+      // if (verbosity >= lvlVomit) {
+      //   curl_easy_setopt(req, CURLOPT_VERBOSE, 1);
+      //   curl_easy_setopt(req, CURLOPT_DEBUGFUNCTION,
+      //                    DownloadItem::debugCallback);
+      // }
 
       curl_easy_setopt(req, CURLOPT_URL, request.uri.c_str());
       curl_easy_setopt(req, CURLOPT_FOLLOWLOCATION, 1L);
@@ -329,10 +329,10 @@ struct CurlDownloader : public Downloader {
       curl_easy_getinfo(req, CURLINFO_EFFECTIVE_URL, &effectiveUriCStr);
       if (effectiveUriCStr) result.effectiveUri = effectiveUriCStr;
 
-      debug(
-          "finished %s of '%s'; curl status = %d, HTTP status = %d, body = %d "
-          "bytes",
-          request.verb(), request.uri, code, httpStatus, result.bodySize);
+      DLOG(INFO) << "finished " << request.verb() << " of " << request.uri
+                 << "; curl status = " << code
+                 << ", HTTP status = " << httpStatus
+                 << ", body = " << result.bodySize << " bytes";
 
       if (decompressionSink) {
         try {
@@ -356,7 +356,6 @@ struct CurlDownloader : public Downloader {
                 httpStatus == 226 /* FTP */ ||
                 httpStatus == 0 /* other protocol */)) {
         result.cached = httpStatus == 304;
-        act.progress(result.bodySize, result.bodySize);
         done = true;
         callback(std::move(result));
       }
@@ -441,11 +440,12 @@ struct CurlDownloader : public Downloader {
                    std::pow(2.0f, attempt - 1 +
                                       std::uniform_real_distribution<>(
                                           0.0, 0.5)(downloader.mt19937));
-          if (writtenToSink)
-            warn("%s; retrying from offset %d in %d ms", exc.what(),
-                 writtenToSink, ms);
-          else
-            warn("%s; retrying in %d ms", exc.what(), ms);
+          if (writtenToSink) {
+            LOG(WARNING) << exc.what() << "; retrying from offset "
+                         << writtenToSink << " in " << ms << "ms";
+          } else {
+            LOG(WARNING) << exc.what() << "; retrying in " << ms << "ms";
+          }
           embargo =
               std::chrono::steady_clock::now() + std::chrono::milliseconds(ms);
           downloader.enqueueItem(shared_from_this());
@@ -565,7 +565,7 @@ struct CurlDownloader : public Downloader {
                         nextWakeup - std::chrono::steady_clock::now())
                         .count())
               : maxSleepTimeMs;
-      vomit("download thread waiting for %d ms", sleepTimeMs);
+      DLOG(INFO) << "download thread waiting for " << sleepTimeMs << " ms";
       mc = curl_multi_wait(curlm, extraFDs, 1, sleepTimeMs, &numfds);
       if (mc != CURLM_OK)
         throw nix::Error(format("unexpected error from curl_multi_wait(): %s") %
@@ -604,7 +604,8 @@ struct CurlDownloader : public Downloader {
       }
 
       for (auto& item : incoming) {
-        debug("starting %s of %s", item->request.verb(), item->request.uri);
+        DLOG(INFO) << "starting " << item->request.verb() << " of "
+                   << item->request.uri;
         item->init();
         curl_multi_add_handle(curlm, item->req);
         item->active = true;
@@ -612,7 +613,7 @@ struct CurlDownloader : public Downloader {
       }
     }
 
-    debug("download thread shutting down");
+    DLOG(INFO) << "download thread shutting down";
   }
 
   void workerThreadEntry() {
@@ -620,7 +621,7 @@ struct CurlDownloader : public Downloader {
       workerThreadMain();
     } catch (nix::Interrupted& e) {
     } catch (std::exception& e) {
-      printError("unexpected error in download thread: %s", e.what());
+      LOG(ERROR) << "unexpected error in download thread: " << e.what();
     }
 
     {
@@ -762,7 +763,7 @@ void Downloader::download(DownloadRequest&& request, Sink& sink) {
        download thread. (Hopefully sleeping will throttle the
        sender.) */
     if (state->data.size() > 1024 * 1024) {
-      debug("download buffer is full; going to sleep");
+      DLOG(INFO) << "download buffer is full; going to sleep";
       state.wait_for(state->request, std::chrono::seconds(10));
     }
 
@@ -870,7 +871,7 @@ CachedDownloadResult Downloader::downloadCached(
           result.effectiveUri = request.uri;
           result.etag = ss[1];
         } else if (!ss[1].empty()) {
-          debug(format("verifying previous ETag '%1%'") % ss[1]);
+          DLOG(INFO) << "verifying previous ETag: " << ss[1];
           expectedETag = ss[1];
         }
       }
@@ -908,7 +909,7 @@ CachedDownloadResult Downloader::downloadCached(
                 url + "\n" + res.etag + "\n" + std::to_string(time(0)) + "\n");
     } catch (DownloadError& e) {
       if (storePath.empty()) throw;
-      warn("warning: %s; using cached result", e.msg());
+      LOG(WARNING) << e.msg() << "; using cached result";
       result.etag = expectedETag;
     }
   }
@@ -924,7 +925,7 @@ CachedDownloadResult Downloader::downloadCached(
       if (!store->isValidPath(unpackedStorePath)) unpackedStorePath = "";
     }
     if (unpackedStorePath.empty()) {
-      printInfo(format("unpacking '%1%'...") % url);
+      LOG(INFO) << "unpacking '" << url << "' ...";
       Path tmpDir = createTempDir();
       AutoDelete autoDelete(tmpDir, true);
       // FIXME: this requires GNU tar for decompression.
diff --git a/third_party/nix/src/libstore/download.hh b/third_party/nix/src/libstore/download.hh
index 8e07403bcc..8859b093e4 100644
--- a/third_party/nix/src/libstore/download.hh
+++ b/third_party/nix/src/libstore/download.hh
@@ -46,14 +46,12 @@ struct DownloadRequest {
   bool head = false;
   size_t tries = downloadSettings.tries;
   unsigned int baseRetryTimeMs = 250;
-  ActivityId parentAct;
   bool decompress = true;
   std::shared_ptr<std::string> data;
   std::string mimeType;
   std::function<void(char*, size_t)> dataCallback;
 
-  DownloadRequest(const std::string& uri)
-      : uri(uri), parentAct(getCurActivity()) {}
+  DownloadRequest(const std::string& uri) : uri(uri) {}
 
   std::string verb() { return data ? "upload" : "download"; }
 };
diff --git a/third_party/nix/src/libstore/gc.cc b/third_party/nix/src/libstore/gc.cc
index 94cf1b7d41..183b3c1a4a 100644
--- a/third_party/nix/src/libstore/gc.cc
+++ b/third_party/nix/src/libstore/gc.cc
@@ -13,6 +13,7 @@
 #include "derivations.hh"
 #include "finally.hh"
 #include "globals.hh"
+#include "glog/logging.h"
 #include "local-store.hh"
 
 namespace nix {
@@ -28,15 +29,16 @@ static string gcRootsDir = "gcroots";
 AutoCloseFD LocalStore::openGCLock(LockType lockType) {
   Path fnGCLock = (format("%1%/%2%") % stateDir % gcLockName).str();
 
-  debug(format("acquiring global GC lock '%1%'") % fnGCLock);
+  DLOG(INFO) << "acquiring global GC lock " << fnGCLock;
 
   AutoCloseFD fdGCLock =
       open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600);
-  if (!fdGCLock)
+  if (!fdGCLock) {
     throw SysError(format("opening global GC lock '%1%'") % fnGCLock);
+  }
 
   if (!lockFile(fdGCLock.get(), lockType, false)) {
-    printError(format("waiting for the big garbage collector lock..."));
+    LOG(ERROR) << "waiting for the big garbage collector lock...";
     lockFile(fdGCLock.get(), lockType, true);
   }
 
@@ -116,12 +118,12 @@ Path LocalFSStore::addPermRoot(const Path& _storePath, const Path& _gcRoot,
      gcroots directory. */
   if (settings.checkRootReachability) {
     Roots roots = findRoots(false);
-    if (roots[storePath].count(gcRoot) == 0)
-      printError(
-          format("warning: '%1%' is not in a directory where the garbage "
-                 "collector looks for roots; "
-                 "therefore, '%2%' might be removed by the garbage collector") %
-          gcRoot % storePath);
+    if (roots[storePath].count(gcRoot) == 0) {
+      LOG(ERROR) << "warning: '" << gcRoot
+                 << "' is not in a directory where the garbage "
+                 << "collector looks for roots; therefore, '" << storePath
+                 << "' might be removed by the garbage collector";
+    }
   }
 
   /* Grab the global GC root, causing us to block while a GC is in
@@ -149,7 +151,7 @@ void LocalStore::addTempRoot(const Path& path) {
 
       fdGCLock = -1;
 
-      debug(format("acquiring read lock on '%1%'") % fnTempRoots);
+      DLOG(INFO) << "acquiring read lock on " << fnTempRoots;
       lockFile(state->fdTempRoots.get(), ltRead, true);
 
       /* Check whether the garbage collector didn't get in our
@@ -167,14 +169,14 @@ void LocalStore::addTempRoot(const Path& path) {
 
   /* Upgrade the lock to a write lock.  This will cause us to block
      if the garbage collector is holding our lock. */
-  debug(format("acquiring write lock on '%1%'") % fnTempRoots);
+  DLOG(INFO) << "acquiring write lock on " << fnTempRoots;
   lockFile(state->fdTempRoots.get(), ltWrite, true);
 
   string s = path + '\0';
   writeFull(state->fdTempRoots.get(), s);
 
   /* Downgrade to a read lock. */
-  debug(format("downgrading to read lock on '%1%'") % fnTempRoots);
+  DLOG(INFO) << "downgrading to read lock on " << fnTempRoots;
   lockFile(state->fdTempRoots.get(), ltRead, true);
 }
 
@@ -188,7 +190,7 @@ void LocalStore::findTempRoots(FDs& fds, Roots& tempRoots, bool censor) {
 
     pid_t pid = std::stoi(i.name);
 
-    debug(format("reading temporary root file '%1%'") % path);
+    DLOG(INFO) << "reading temporary root file " << path;
     FDPtr fd(new AutoCloseFD(open(path.c_str(), O_CLOEXEC | O_RDWR, 0666)));
     if (!*fd) {
       /* It's okay if the file has disappeared. */
@@ -204,7 +206,7 @@ void LocalStore::findTempRoots(FDs& fds, Roots& tempRoots, bool censor) {
        only succeed if the owning process has died.  In that case
        we don't care about its temporary roots. */
     if (lockFile(fd->get(), ltWrite, false)) {
-      printError(format("removing stale temporary roots file '%1%'") % path);
+      LOG(ERROR) << "removing stale temporary roots file " << path;
       unlink(path.c_str());
       writeFull(fd->get(), "d");
       continue;
@@ -213,7 +215,7 @@ void LocalStore::findTempRoots(FDs& fds, Roots& tempRoots, bool censor) {
     /* Acquire a read lock.  This will prevent the owning process
        from upgrading to a write lock, therefore it will block in
        addTempRoot(). */
-    debug(format("waiting for read lock on '%1%'") % path);
+    DLOG(INFO) << "waiting for read lock on " << path;
     lockFile(fd->get(), ltRead, true);
 
     /* Read the entire file. */
@@ -224,7 +226,7 @@ void LocalStore::findTempRoots(FDs& fds, Roots& tempRoots, bool censor) {
 
     while ((end = contents.find((char)0, pos)) != string::npos) {
       Path root(contents, pos, end - pos);
-      debug("got temporary root '%s'", root);
+      DLOG(INFO) << "got temporary root " << root;
       assertStorePath(root);
       tempRoots[root].emplace(censor ? censored : fmt("{temp:%d}", pid));
       pos = end + 1;
@@ -240,8 +242,8 @@ void LocalStore::findRoots(const Path& path, unsigned char type, Roots& roots) {
     if (isStorePath(storePath) && isValidPath(storePath))
       roots[storePath].emplace(path);
     else
-      printInfo(format("skipping invalid root from '%1%' to '%2%'") % path %
-                storePath);
+      LOG(INFO) << "skipping invalid root from '" << path << "' to '"
+                << storePath << "'";
   };
 
   try {
@@ -261,8 +263,8 @@ void LocalStore::findRoots(const Path& path, unsigned char type, Roots& roots) {
         target = absPath(target, dirOf(path));
         if (!pathExists(target)) {
           if (isInDir(path, stateDir + "/" + gcRootsDir + "/auto")) {
-            printInfo(format("removing stale link from '%1%' to '%2%'") % path %
-                      target);
+            LOG(INFO) << "removing stale link from '" << path << "' to '"
+                      << target << "'";
             unlink(path.c_str());
           }
         } else {
@@ -284,10 +286,11 @@ void LocalStore::findRoots(const Path& path, unsigned char type, Roots& roots) {
 
   catch (SysError& e) {
     /* We only ignore permanent failures. */
-    if (e.errNo == EACCES || e.errNo == ENOENT || e.errNo == ENOTDIR)
-      printInfo(format("cannot read potential root '%1%'") % path);
-    else
+    if (e.errNo == EACCES || e.errNo == ENOENT || e.errNo == ENOTDIR) {
+      LOG(INFO) << "cannot read potential root '" << path << "'";
+    } else {
       throw;
+    }
   }
 }
 
@@ -319,16 +322,21 @@ try_again:
   char buf[bufsiz];
   auto res = readlink(file.c_str(), buf, bufsiz);
   if (res == -1) {
-    if (errno == ENOENT || errno == EACCES || errno == ESRCH) return;
+    if (errno == ENOENT || errno == EACCES || errno == ESRCH) {
+      return;
+    }
     throw SysError("reading symlink");
   }
   if (res == bufsiz) {
-    if (SSIZE_MAX / 2 < bufsiz) throw Error("stupidly long symlink");
+    if (SSIZE_MAX / 2 < bufsiz) {
+      throw Error("stupidly long symlink");
+    }
     bufsiz *= 2;
     goto try_again;
   }
-  if (res > 0 && buf[0] == '/')
+  if (res > 0 && buf[0] == '/') {
     roots[std::string(static_cast<char*>(buf), res)].emplace(file);
+  }
 }
 
 static string quoteRegexChars(const string& raw) {
@@ -340,7 +348,9 @@ static void readFileRoots(const char* path, Roots& roots) {
   try {
     roots[readFile(path)].emplace(path);
   } catch (SysError& e) {
-    if (e.errNo != ENOENT && e.errNo != EACCES) throw;
+    if (e.errNo != ENOENT && e.errNo != EACCES) {
+      throw;
+    }
   }
 }
 
@@ -434,7 +444,7 @@ void LocalStore::findRuntimeRoots(Roots& roots, bool censor) {
     if (isInStore(target)) {
       Path path = toStorePath(target);
       if (isStorePath(path) && isValidPath(path)) {
-        debug(format("got additional root '%1%'") % path);
+        DLOG(INFO) << "got additional root " << path;
         if (censor)
           roots[path].insert(censored);
         else
@@ -496,7 +506,7 @@ void LocalStore::deletePathRecursive(GCState& state, const Path& path) {
     throw SysError(format("getting status of %1%") % realPath);
   }
 
-  printInfo(format("deleting '%1%'") % path);
+  LOG(INFO) << "deleting '" << path << "'";
 
   state.results.paths.insert(path);
 
@@ -519,8 +529,8 @@ void LocalStore::deletePathRecursive(GCState& state, const Path& path) {
       state.bytesInvalidated += size;
     } catch (SysError& e) {
       if (e.errNo == ENOSPC) {
-        printInfo(format("note: can't create move '%1%': %2%") % realPath %
-                  e.msg());
+        LOG(INFO) << "note: can't create move '" << realPath
+                  << "': " << e.msg();
         deleteGarbage(state, realPath);
       }
     }
@@ -529,8 +539,8 @@ void LocalStore::deletePathRecursive(GCState& state, const Path& path) {
 
   if (state.results.bytesFreed + state.bytesInvalidated >
       state.options.maxFreed) {
-    printInfo(format("deleted or invalidated more than %1% bytes; stopping") %
-              state.options.maxFreed);
+    LOG(INFO) << "deleted or invalidated more than " << state.options.maxFreed
+              << " bytes; stopping";
     throw GCLimitReached();
   }
 }
@@ -544,7 +554,7 @@ bool LocalStore::canReachRoot(GCState& state, PathSet& visited,
   if (state.dead.count(path)) return false;
 
   if (state.roots.count(path)) {
-    debug(format("cannot delete '%1%' because it's a root") % path);
+    DLOG(INFO) << "cannot delete '" << path << "' because it's a root";
     state.alive.insert(path);
     return true;
   }
@@ -611,7 +621,7 @@ void LocalStore::tryToDelete(GCState& state, const Path& path) {
   PathSet visited;
 
   if (canReachRoot(state, visited, path)) {
-    debug(format("cannot delete '%1%' because it's still reachable") % path);
+    DLOG(INFO) << "cannot delete '" << path << "' because it's still reachable";
   } else {
     /* No path we visited was a root, so everything is garbage.
        But we only delete ‘path’ and its referrers here so that
@@ -629,7 +639,9 @@ void LocalStore::tryToDelete(GCState& state, const Path& path) {
    the link count. */
 void LocalStore::removeUnusedLinks(const GCState& state) {
   AutoCloseDir dir(opendir(linksDir.c_str()));
-  if (!dir) throw SysError(format("opening directory '%1%'") % linksDir);
+  if (!dir) {
+    throw SysError(format("opening directory '%1%'") % linksDir);
+  }
 
   long long actualSize = 0, unsharedSize = 0;
 
@@ -650,21 +662,26 @@ void LocalStore::removeUnusedLinks(const GCState& state) {
       continue;
     }
 
-    printMsg(lvlTalkative, format("deleting unused link '%1%'") % path);
+    LOG(INFO) << "deleting unused link " << path;
 
-    if (unlink(path.c_str()) == -1)
+    if (unlink(path.c_str()) == -1) {
       throw SysError(format("deleting '%1%'") % path);
+    }
 
     state.results.bytesFreed += st.st_size;
   }
 
   struct stat st;
-  if (stat(linksDir.c_str(), &st) == -1)
+  if (stat(linksDir.c_str(), &st) == -1) {
     throw SysError(format("statting '%1%'") % linksDir);
+  }
+
   long long overhead = st.st_blocks * 512ULL;
 
-  printInfo(format("note: currently hard linking saves %.2f MiB") %
-            ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
+  // TODO(tazjin): absl::StrFormat %.2f
+  LOG(INFO) << "note: currently hard linking saves "
+            << ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0))
+            << " MiB";
 }
 
 void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) {
@@ -694,11 +711,15 @@ void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) {
 
   /* Find the roots.  Since we've grabbed the GC lock, the set of
      permanent roots cannot increase now. */
-  printError(format("finding garbage collector roots..."));
+  LOG(INFO) << "finding garbage collector roots...";
   Roots rootMap;
-  if (!options.ignoreLiveness) findRootsNoTemp(rootMap, true);
+  if (!options.ignoreLiveness) {
+    findRootsNoTemp(rootMap, true);
+  }
 
-  for (auto& i : rootMap) state.roots.insert(i.first);
+  for (auto& i : rootMap) {
+    state.roots.insert(i.first);
+  }
 
   /* Read the temporary roots.  This acquires read locks on all
      per-process temporary root files.  So after this point no paths
@@ -719,7 +740,7 @@ void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) {
       createDirs(trashDir);
     } catch (SysError& e) {
       if (e.errNo == ENOSPC) {
-        printInfo(format("note: can't create trash directory: %1%") % e.msg());
+        LOG(INFO) << "note: can't create trash directory: " << e.msg();
         state.moveToTrash = false;
       }
     }
@@ -739,14 +760,15 @@ void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) {
 
   } else if (options.maxFreed > 0) {
     if (state.shouldDelete)
-      printError(format("deleting garbage..."));
+      LOG(INFO) << "deleting garbage...";
     else
-      printError(format("determining live/dead paths..."));
+      LOG(ERROR) << "determining live/dead paths...";
 
     try {
       AutoCloseDir dir(opendir(realStoreDir.c_str()));
-      if (!dir)
+      if (!dir) {
         throw SysError(format("opening directory '%1%'") % realStoreDir);
+      }
 
       /* Read the store and immediately delete all paths that
          aren't valid.  When using --max-freed etc., deleting
@@ -799,13 +821,13 @@ void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) {
   fds.clear();
 
   /* Delete the trash directory. */
-  printInfo(format("deleting '%1%'") % trashDir);
+  LOG(INFO) << "deleting " << trashDir;
   deleteGarbage(state, trashDir);
 
   /* Clean up the links directory. */
   if (options.action == GCOptions::gcDeleteDead ||
       options.action == GCOptions::gcDeleteSpecific) {
-    printError(format("deleting unused links..."));
+    LOG(INFO) << "deleting unused links...";
     removeUnusedLinks(state);
   }
 
@@ -821,8 +843,9 @@ void LocalStore::autoGC(bool sync) {
       return std::stoll(readFile(fakeFreeSpaceFile));
 
     struct statvfs st;
-    if (statvfs(realStoreDir.c_str(), &st))
+    if (statvfs(realStoreDir.c_str(), &st)) {
       throw SysError("getting filesystem info about '%s'", realStoreDir);
+    }
 
     return (uint64_t)st.f_bavail * st.f_bsize;
   };
@@ -834,7 +857,7 @@ void LocalStore::autoGC(bool sync) {
 
     if (state->gcRunning) {
       future = state->gcFuture;
-      debug("waiting for auto-GC to finish");
+      DLOG(INFO) << "waiting for auto-GC to finish";
       goto sync;
     }
 
@@ -870,7 +893,7 @@ void LocalStore::autoGC(bool sync) {
         GCOptions options;
         options.maxFreed = settings.maxFree - avail;
 
-        printInfo("running auto-GC to free %d bytes", options.maxFreed);
+        LOG(INFO) << "running auto-GC to free " << options.maxFreed << " bytes";
 
         GCResults results;
 
diff --git a/third_party/nix/src/libstore/http-binary-cache-store.cc b/third_party/nix/src/libstore/http-binary-cache-store.cc
index eb21babd51..06935ce61d 100644
--- a/third_party/nix/src/libstore/http-binary-cache-store.cc
+++ b/third_party/nix/src/libstore/http-binary-cache-store.cc
@@ -1,3 +1,4 @@
+#include <glog/logging.h>
 #include "binary-cache-store.hh"
 #include "download.hh"
 #include "globals.hh"
@@ -45,7 +46,8 @@ class HttpBinaryCacheStore : public BinaryCacheStore {
     auto state(_state.lock());
     if (state->enabled && settings.tryFallback) {
       int t = 60;
-      printError("disabling binary cache '%s' for %s seconds", getUri(), t);
+      LOG(WARNING) << "disabling binary cache '" << getUri() << "' for " << t
+                   << " seconds";
       state->enabled = false;
       state->disabledUntil =
           std::chrono::steady_clock::now() + std::chrono::seconds(t);
@@ -57,7 +59,7 @@ class HttpBinaryCacheStore : public BinaryCacheStore {
     if (state->enabled) return;
     if (std::chrono::steady_clock::now() > state->disabledUntil) {
       state->enabled = true;
-      debug("re-enabling binary cache '%s'", getUri());
+      DLOG(INFO) << "re-enabling binary cache '" << getUri() << "'";
       return;
     }
     throw SubstituterDisabled("substituter '%s' is disabled", getUri());
diff --git a/third_party/nix/src/libstore/legacy-ssh-store.cc b/third_party/nix/src/libstore/legacy-ssh-store.cc
index 4dc6c0fbec..893b454ac6 100644
--- a/third_party/nix/src/libstore/legacy-ssh-store.cc
+++ b/third_party/nix/src/libstore/legacy-ssh-store.cc
@@ -1,5 +1,6 @@
 #include "archive.hh"
 #include "derivations.hh"
+#include "glog/logging.h"
 #include "pool.hh"
 #include "remote-store.hh"
 #include "serve-protocol.hh"
@@ -90,7 +91,8 @@ struct LegacySSHStore : public Store {
     try {
       auto conn(connections->get());
 
-      debug("querying remote host '%s' for info on '%s'", host, path);
+      DLOG(INFO) << "querying remote host '" << host << "' for info on '"
+                 << path << "'";
 
       conn->to << cmdQueryPathInfos << PathSet{path};
       conn->to.flush();
@@ -125,7 +127,8 @@ struct LegacySSHStore : public Store {
   void addToStore(const ValidPathInfo& info, Source& source, RepairFlag repair,
                   CheckSigsFlag checkSigs,
                   std::shared_ptr<FSAccessor> accessor) override {
-    debug("adding path '%s' to remote host '%s'", info.path, host);
+    DLOG(INFO) << "adding path '" << info.path << "' to remote host '" << host
+               << "'";
 
     auto conn(connections->get());
 
diff --git a/third_party/nix/src/libstore/local-store.cc b/third_party/nix/src/libstore/local-store.cc
index 9da8e9d435..93a1eab26b 100644
--- a/third_party/nix/src/libstore/local-store.cc
+++ b/third_party/nix/src/libstore/local-store.cc
@@ -1,6 +1,7 @@
 #include "local-store.hh"
 #include <errno.h>
 #include <fcntl.h>
+#include <glog/logging.h>
 #include <grp.h>
 #include <stdio.h>
 #include <sys/select.h>
@@ -81,11 +82,10 @@ LocalStore::LocalStore(const Params& params)
     mode_t perm = 01775;
 
     struct group* gr = getgrnam(settings.buildUsersGroup.get().c_str());
-    if (!gr)
-      printError(format("warning: the group '%1%' specified in "
-                        "'build-users-group' does not exist") %
-                 settings.buildUsersGroup);
-    else {
+    if (!gr) {
+      LOG(ERROR) << "warning: the group '" << settings.buildUsersGroup
+                 << "' specified in 'build-users-group' does not exist";
+    } else {
       struct stat st;
       if (stat(realStoreDir.c_str(), &st))
         throw SysError(format("getting attributes of path '%1%'") %
@@ -147,7 +147,7 @@ LocalStore::LocalStore(const Params& params)
   globalLock = openLockFile(globalLockPath.c_str(), true);
 
   if (!lockFile(globalLock.get(), ltRead, false)) {
-    printError("waiting for the big Nix store lock...");
+    LOG(INFO) << "waiting for the big Nix store lock...";
     lockFile(globalLock.get(), ltRead, true);
   }
 
@@ -180,7 +180,7 @@ LocalStore::LocalStore(const Params& params)
           "please upgrade Nix to version 1.11 first.");
 
     if (!lockFile(globalLock.get(), ltWrite, false)) {
-      printError("waiting for exclusive access to the Nix store...");
+      LOG(INFO) << "waiting for exclusive access to the Nix store...";
       lockFile(globalLock.get(), ltWrite, true);
     }
 
@@ -272,7 +272,7 @@ LocalStore::~LocalStore() {
   }
 
   if (future.valid()) {
-    printError("waiting for auto-GC to finish on exit...");
+    LOG(INFO) << "waiting for auto-GC to finish on exit...";
     future.get();
   }
 
@@ -850,8 +850,8 @@ void LocalStore::querySubstitutablePathInfos(const PathSet& paths,
     if (sub->storeDir != storeDir) continue;
     for (auto& path : paths) {
       if (infos.count(path)) continue;
-      debug(format("checking substituter '%s' for path '%s'") % sub->getUri() %
-            path);
+      DLOG(INFO) << "checking substituter '" << sub->getUri() << "' for path '"
+                 << path << "'";
       try {
         auto info = sub->queryPathInfo(path);
         auto narInfo = std::dynamic_pointer_cast<const NarInfo>(
@@ -862,10 +862,11 @@ void LocalStore::querySubstitutablePathInfos(const PathSet& paths,
       } catch (InvalidPath&) {
       } catch (SubstituterDisabled&) {
       } catch (Error& e) {
-        if (settings.tryFallback)
-          printError(e.what());
-        else
+        if (settings.tryFallback) {
+          LOG(ERROR) << e.what();
+        } else {
           throw;
+        }
       }
     }
   }
@@ -931,7 +932,7 @@ void LocalStore::registerValidPaths(const ValidPathInfos& infos) {
 /* Invalidate a path.  The caller is responsible for checking that
    there are no referrers. */
 void LocalStore::invalidatePath(State& state, const Path& path) {
-  debug(format("invalidating path '%1%'") % path);
+  LOG(INFO) << "invalidating path '" << path << "'";
 
   state.stmtInvalidatePath.use()(path).exec();
 
@@ -954,12 +955,15 @@ const PublicKeys& LocalStore::getPublicKeys() {
 void LocalStore::addToStore(const ValidPathInfo& info, Source& source,
                             RepairFlag repair, CheckSigsFlag checkSigs,
                             std::shared_ptr<FSAccessor> accessor) {
-  if (!info.narHash)
+  if (!info.narHash) {
     throw Error("cannot add path '%s' because it lacks a hash", info.path);
+  }
 
-  if (requireSigs && checkSigs && !info.checkSignatures(*this, getPublicKeys()))
+  if (requireSigs && checkSigs &&
+      !info.checkSignatures(*this, getPublicKeys())) {
     throw Error("cannot add path '%s' because it lacks a valid signature",
                 info.path);
+  }
 
   addTempRoot(info.path);
 
@@ -1168,7 +1172,7 @@ void LocalStore::invalidatePathChecked(const Path& path) {
 }
 
 bool LocalStore::verifyStore(bool checkContents, RepairFlag repair) {
-  printError(format("reading the Nix store..."));
+  LOG(INFO) << "reading the Nix store...";
 
   bool errors = false;
 
@@ -1180,7 +1184,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair) {
   for (auto& i : readDirectory(realStoreDir)) store.insert(i.name);
 
   /* Check whether all valid paths actually exist. */
-  printInfo("checking path existence...");
+  LOG(INFO) << "checking path existence...";
 
   PathSet validPaths2 = queryAllValidPaths(), validPaths, done;
 
@@ -1191,7 +1195,7 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair) {
 
   /* Optionally, check the content hashes (slow). */
   if (checkContents) {
-    printInfo("checking hashes...");
+    LOG(INFO) << "checking hashes...";
 
     Hash nullHash(htSHA256);
 
@@ -1201,31 +1205,32 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair) {
             std::shared_ptr<const ValidPathInfo>(queryPathInfo(i)));
 
         /* Check the content hash (optionally - slow). */
-        printMsg(lvlTalkative, format("checking contents of '%1%'") % i);
+        DLOG(INFO) << "checking contents of '" << i << "'";
         HashResult current = hashPath(info->narHash.type, toRealPath(i));
 
         if (info->narHash != nullHash && info->narHash != current.first) {
-          printError(format("path '%1%' was modified! "
-                            "expected hash '%2%', got '%3%'") %
-                     i % info->narHash.to_string() % current.first.to_string());
-          if (repair)
+          LOG(ERROR) << "path '" << i << "' was modified! expected hash '"
+                     << info->narHash.to_string() << "', got '"
+                     << current.first.to_string() << "'";
+          if (repair) {
             repairPath(i);
-          else
+          } else {
             errors = true;
+          }
         } else {
           bool update = false;
 
           /* Fill in missing hashes. */
           if (info->narHash == nullHash) {
-            printError(format("fixing missing hash on '%1%'") % i);
+            LOG(WARNING) << "fixing missing hash on '" << i << "'";
             info->narHash = current.first;
             update = true;
           }
 
           /* Fill in missing narSize fields (from old stores). */
           if (info->narSize == 0) {
-            printError(format("updating size field on '%1%' to %2%") % i %
-                       current.second);
+            LOG(ERROR) << "updating size field on '" << i << "' to "
+                       << current.second;
             info->narSize = current.second;
             update = true;
           }
@@ -1239,10 +1244,11 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair) {
       } catch (Error& e) {
         /* It's possible that the path got GC'ed, so ignore
            errors on invalid paths. */
-        if (isValidPath(i))
-          printError(format("error: %1%") % e.msg());
-        else
-          printError(format("warning: %1%") % e.msg());
+        if (isValidPath(i)) {
+          LOG(ERROR) << e.msg();
+        } else {
+          LOG(WARNING) << e.msg();
+        }
         errors = true;
       }
     }
@@ -1256,11 +1262,13 @@ void LocalStore::verifyPath(const Path& path, const PathSet& store,
                             RepairFlag repair, bool& errors) {
   checkInterrupt();
 
-  if (done.find(path) != done.end()) return;
+  if (done.find(path) != done.end()) {
+    return;
+  }
   done.insert(path);
 
   if (!isStorePath(path)) {
-    printError(format("path '%1%' is not in the Nix store") % path);
+    LOG(ERROR) << "path '" << path << "' is not in the Nix store";
     auto state(_state.lock());
     invalidatePath(*state, path);
     return;
@@ -1279,18 +1287,17 @@ void LocalStore::verifyPath(const Path& path, const PathSet& store,
       }
 
     if (canInvalidate) {
-      printError(format("path '%1%' disappeared, removing from database...") %
-                 path);
+      LOG(WARNING) << "path '" << path
+                   << "' disappeared, removing from database...";
       auto state(_state.lock());
       invalidatePath(*state, path);
     } else {
-      printError(
-          format("path '%1%' disappeared, but it still has valid referrers!") %
-          path);
+      LOG(ERROR) << "path '" << path
+                 << "' disappeared, but it still has valid referrers!";
       if (repair) try {
           repairPath(path);
         } catch (Error& e) {
-          printError(format("warning: %1%") % e.msg());
+          LOG(WARNING) << e.msg();
           errors = true;
         }
       else
diff --git a/third_party/nix/src/libstore/local-store.hh b/third_party/nix/src/libstore/local-store.hh
index c1cd776a74..20d372fc8d 100644
--- a/third_party/nix/src/libstore/local-store.hh
+++ b/third_party/nix/src/libstore/local-store.hh
@@ -268,7 +268,7 @@ class LocalStore : public LocalFSStore {
   InodeHash loadInodeHash();
   Strings readDirectoryIgnoringInodes(const Path& path,
                                       const InodeHash& inodeHash);
-  void optimisePath_(Activity* act, OptimiseStats& stats, const Path& path,
+  void optimisePath_(OptimiseStats& stats, const Path& path,
                      InodeHash& inodeHash);
 
   // Internal versions that are not wrapped in retry_sqlite.
diff --git a/third_party/nix/src/libstore/machines.cc b/third_party/nix/src/libstore/machines.cc
index 526afdbbc0..0bd65c2302 100644
--- a/third_party/nix/src/libstore/machines.cc
+++ b/third_party/nix/src/libstore/machines.cc
@@ -1,4 +1,5 @@
 #include "machines.hh"
+#include <glog/logging.h>
 #include <algorithm>
 #include "globals.hh"
 #include "util.hh"
@@ -53,15 +54,19 @@ void parseMachines(const std::string& s, Machines& machines) {
       try {
         parseMachines(readFile(file), machines);
       } catch (const SysError& e) {
-        if (e.errNo != ENOENT) throw;
-        debug("cannot find machines file '%s'", file);
+        if (e.errNo != ENOENT) {
+          throw;
+        }
+        DLOG(INFO) << "cannot find machines file: " << file;
       }
       continue;
     }
 
     auto tokens = tokenizeString<std::vector<string>>(line);
     auto sz = tokens.size();
-    if (sz < 1) throw FormatError("bad machine specification '%s'", line);
+    if (sz < 1) {
+      throw FormatError("bad machine specification '%s'", line);
+    }
 
     auto isSet = [&](size_t n) {
       return tokens.size() > n && tokens[n] != "" && tokens[n] != "-";
diff --git a/third_party/nix/src/libstore/meson.build b/third_party/nix/src/libstore/meson.build
index 28ae0fdb27..700793bdea 100644
--- a/third_party/nix/src/libstore/meson.build
+++ b/third_party/nix/src/libstore/meson.build
@@ -79,6 +79,7 @@ libstore_data = files(
 #============================================================================
 
 libstore_dep_list = [
+    glog_dep,
     libbz2_dep,
     libcurl_dep,
     libdl_dep,
diff --git a/third_party/nix/src/libstore/misc.cc b/third_party/nix/src/libstore/misc.cc
index d1c4dc1550..5139404597 100644
--- a/third_party/nix/src/libstore/misc.cc
+++ b/third_party/nix/src/libstore/misc.cc
@@ -1,3 +1,4 @@
+#include <glog/logging.h>
 #include "derivations.hh"
 #include "globals.hh"
 #include "local-store.hh"
@@ -99,8 +100,7 @@ void Store::queryMissing(const PathSet& targets, PathSet& willBuild_,
                          PathSet& willSubstitute_, PathSet& unknown_,
                          unsigned long long& downloadSize_,
                          unsigned long long& narSize_) {
-  Activity act(*logger, lvlDebug, actUnknown,
-               "querying info about missing paths");
+  LOG(INFO) << "querying info about missing paths";
 
   downloadSize_ = narSize_ = 0;
 
diff --git a/third_party/nix/src/libstore/nar-info-disk-cache.cc b/third_party/nix/src/libstore/nar-info-disk-cache.cc
index 2121e89387..cbd1f5a12a 100644
--- a/third_party/nix/src/libstore/nar-info-disk-cache.cc
+++ b/third_party/nix/src/libstore/nar-info-disk-cache.cc
@@ -1,4 +1,5 @@
 #include "nar-info-disk-cache.hh"
+#include <glog/logging.h>
 #include <sqlite3.h>
 #include "globals.hh"
 #include "sqlite.hh"
@@ -126,8 +127,8 @@ class NarInfoDiskCacheImpl : public NarInfoDiskCache {
                 now - settings.ttlPositiveNarInfoCache)
             .exec();
 
-        debug("deleted %d entries from the NAR info disk cache",
-              sqlite3_changes(state->db));
+        DLOG(INFO) << "deleted " << sqlite3_changes(state->db)
+                   << " entries from the NAR info disk cache";
 
         SQLiteStmt(
             state->db,
diff --git a/third_party/nix/src/libstore/optimise-store.cc b/third_party/nix/src/libstore/optimise-store.cc
index b43919a2bb..98bff94e97 100644
--- a/third_party/nix/src/libstore/optimise-store.cc
+++ b/third_party/nix/src/libstore/optimise-store.cc
@@ -7,6 +7,7 @@
 #include <cstring>
 #include <regex>
 #include "globals.hh"
+#include "glog/logging.h"
 #include "local-store.hh"
 #include "util.hh"
 
@@ -34,11 +35,13 @@ struct MakeReadOnly {
 };
 
 LocalStore::InodeHash LocalStore::loadInodeHash() {
-  debug("loading hash inodes in memory");
+  DLOG(INFO) << "loading hash inodes in memory";
   InodeHash inodeHash;
 
   AutoCloseDir dir(opendir(linksDir.c_str()));
-  if (!dir) throw SysError(format("opening directory '%1%'") % linksDir);
+  if (!dir) {
+    throw SysError(format("opening directory '%1%'") % linksDir);
+  }
 
   struct dirent* dirent;
   while (errno = 0, dirent = readdir(dir.get())) { /* sic */
@@ -46,9 +49,11 @@ LocalStore::InodeHash LocalStore::loadInodeHash() {
     // We don't care if we hit non-hash files, anything goes
     inodeHash.insert(dirent->d_ino);
   }
-  if (errno) throw SysError(format("reading directory '%1%'") % linksDir);
+  if (errno) {
+    throw SysError(format("reading directory '%1%'") % linksDir);
+  }
 
-  printMsg(lvlTalkative, format("loaded %1% hash inodes") % inodeHash.size());
+  DLOG(INFO) << "loaded " << inodeHash.size() << " hash inodes";
 
   return inodeHash;
 }
@@ -58,14 +63,16 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path& path,
   Strings names;
 
   AutoCloseDir dir(opendir(path.c_str()));
-  if (!dir) throw SysError(format("opening directory '%1%'") % path);
+  if (!dir) {
+    throw SysError(format("opening directory '%1%'") % path);
+  }
 
   struct dirent* dirent;
   while (errno = 0, dirent = readdir(dir.get())) { /* sic */
     checkInterrupt();
 
     if (inodeHash.count(dirent->d_ino)) {
-      debug(format("'%1%' is already linked") % dirent->d_name);
+      DLOG(WARNING) << dirent->d_name << " is already linked";
       continue;
     }
 
@@ -73,13 +80,15 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path& path,
     if (name == "." || name == "..") continue;
     names.push_back(name);
   }
-  if (errno) throw SysError(format("reading directory '%1%'") % path);
+  if (errno) {
+    throw SysError(format("reading directory '%1%'") % path);
+  }
 
   return names;
 }
 
-void LocalStore::optimisePath_(Activity* act, OptimiseStats& stats,
-                               const Path& path, InodeHash& inodeHash) {
+void LocalStore::optimisePath_(OptimiseStats& stats, const Path& path,
+                               InodeHash& inodeHash) {
   checkInterrupt();
 
   struct stat st;
@@ -100,7 +109,7 @@ void LocalStore::optimisePath_(Activity* act, OptimiseStats& stats,
 
   if (S_ISDIR(st.st_mode)) {
     Strings names = readDirectoryIgnoringInodes(path, inodeHash);
-    for (auto& i : names) optimisePath_(act, stats, path + "/" + i, inodeHash);
+    for (auto& i : names) optimisePath_(stats, path + "/" + i, inodeHash);
     return;
   }
 
@@ -117,14 +126,14 @@ void LocalStore::optimisePath_(Activity* act, OptimiseStats& stats,
      NixOS (example: $fontconfig/var/cache being modified).  Skip
      those files.  FIXME: check the modification time. */
   if (S_ISREG(st.st_mode) && (st.st_mode & S_IWUSR)) {
-    printError(format("skipping suspicious writable file '%1%'") % path);
+    LOG(WARNING) << "skipping suspicious writable file '" << path << "'";
     return;
   }
 
   /* This can still happen on top-level files. */
   if (st.st_nlink > 1 && inodeHash.count(st.st_ino)) {
-    debug(format("'%1%' is already linked, with %2% other file(s)") % path %
-          (st.st_nlink - 2));
+    DLOG(INFO) << path << " is already linked, with " << (st.st_nlink - 2)
+               << " other file(s)";
     return;
   }
 
@@ -138,7 +147,7 @@ void LocalStore::optimisePath_(Activity* act, OptimiseStats& stats,
      contents of the symlink (i.e. the result of readlink()), not
      the contents of the target (which may not even exist). */
   Hash hash = hashPath(htSHA256, path).first;
-  debug(format("'%1%' has hash '%2%'") % path % hash.to_string());
+  LOG(INFO) << path << " has hash " << hash.to_string();
 
   /* Check if this is a known hash. */
   Path linkPath = linksDir + "/" + hash.to_string(Base32, false);
@@ -162,8 +171,9 @@ retry:
            full.  When that happens, it's fine to ignore it: we
            just effectively disable deduplication of this
            file.  */
-        printInfo("cannot link '%s' to '%s': %s", linkPath, path,
-                  strerror(errno));
+        LOG(WARNING) << "cannot link '" << linkPath << " to " << path << ": "
+                     << strerror(errno);
+
         return;
 
       default:
@@ -178,17 +188,17 @@ retry:
     throw SysError(format("getting attributes of path '%1%'") % linkPath);
 
   if (st.st_ino == stLink.st_ino) {
-    debug(format("'%1%' is already linked to '%2%'") % path % linkPath);
+    DLOG(INFO) << path << " is already linked to " << linkPath;
     return;
   }
 
   if (st.st_size != stLink.st_size) {
-    printError(format("removing corrupted link '%1%'") % linkPath);
+    LOG(WARNING) << "removing corrupted link '" << linkPath << "'";
     unlink(linkPath.c_str());
     goto retry;
   }
 
-  printMsg(lvlTalkative, format("linking '%1%' to '%2%'") % path % linkPath);
+  DLOG(INFO) << "linking '" << path << "' to '" << linkPath << "'";
 
   /* Make the containing directory writable, but only if it's not
      the store itself (we don't want or need to mess with its
@@ -209,8 +219,9 @@ retry:
       /* Too many links to the same file (>= 32000 on most file
          systems).  This is likely to happen with empty files.
          Just shrug and ignore. */
-      if (st.st_size)
-        printInfo(format("'%1%' has maximum number of links") % linkPath);
+      if (st.st_size) {
+        LOG(WARNING) << linkPath << " has maximum number of links";
+      }
       return;
     }
     throw SysError("cannot link '%1%' to '%2%'", tempLink, linkPath);
@@ -218,14 +229,16 @@ retry:
 
   /* Atomically replace the old file with the new hard link. */
   if (rename(tempLink.c_str(), path.c_str()) == -1) {
-    if (unlink(tempLink.c_str()) == -1)
-      printError(format("unable to unlink '%1%'") % tempLink);
+    if (unlink(tempLink.c_str()) == -1) {
+      LOG(ERROR) << "unable to unlink '" << tempLink << "'";
+    }
     if (errno == EMLINK) {
       /* Some filesystems generate too many links on the rename,
          rather than on the original link.  (Probably it
          temporarily increases the st_nlink field before
          decreasing it again.) */
-      debug("'%s' has reached maximum number of links", linkPath);
+      DLOG(WARNING) << "'" << linkPath
+                    << "' has reached maximum number of links";
       return;
     }
     throw SysError(format("cannot rename '%1%' to '%2%'") % tempLink % path);
@@ -234,30 +247,22 @@ retry:
   stats.filesLinked++;
   stats.bytesFreed += st.st_size;
   stats.blocksFreed += st.st_blocks;
-
-  if (act) act->result(resFileLinked, st.st_size, st.st_blocks);
 }
 
 void LocalStore::optimiseStore(OptimiseStats& stats) {
-  Activity act(*logger, actOptimiseStore);
-
   PathSet paths = queryAllValidPaths();
   InodeHash inodeHash = loadInodeHash();
 
-  act.progress(0, paths.size());
-
   uint64_t done = 0;
 
   for (auto& i : paths) {
     addTempRoot(i);
     if (!isValidPath(i)) continue; /* path was GC'ed, probably */
     {
-      Activity act(*logger, lvlTalkative, actUnknown,
-                   fmt("optimising path '%s'", i));
-      optimisePath_(&act, stats, realStoreDir + "/" + baseNameOf(i), inodeHash);
+      LOG(INFO) << "optimising path '" << i << "'";
+      optimisePath_(stats, realStoreDir + "/" + baseNameOf(i), inodeHash);
     }
     done++;
-    act.progress(done, paths.size());
   }
 }
 
@@ -270,16 +275,17 @@ void LocalStore::optimiseStore() {
 
   optimiseStore(stats);
 
-  printInfo(format("%1% freed by hard-linking %2% files") %
-            showBytes(stats.bytesFreed) % stats.filesLinked);
+  LOG(INFO) << showBytes(stats.bytesFreed) << " freed by hard-linking "
+            << stats.filesLinked << " files";
 }
 
 void LocalStore::optimisePath(const Path& path) {
   OptimiseStats stats;
   InodeHash inodeHash;
 
-  if (settings.autoOptimiseStore)
-    optimisePath_(nullptr, stats, path, inodeHash);
+  if (settings.autoOptimiseStore) {
+    optimisePath_(stats, path, inodeHash);
+  }
 }
 
 }  // namespace nix
diff --git a/third_party/nix/src/libstore/pathlocks.cc b/third_party/nix/src/libstore/pathlocks.cc
index 7fa32e21a6..986b543845 100644
--- a/third_party/nix/src/libstore/pathlocks.cc
+++ b/third_party/nix/src/libstore/pathlocks.cc
@@ -1,5 +1,6 @@
 #include "pathlocks.hh"
 #include <fcntl.h>
+#include <glog/logging.h>
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -82,7 +83,7 @@ bool PathLocks::lockPaths(const PathSet& paths, const string& waitMsg,
     checkInterrupt();
     Path lockPath = path + ".lock";
 
-    debug(format("locking path '%1%'") % path);
+    DLOG(INFO) << "locking path '" << path << "'";
 
     AutoCloseFD fd;
 
@@ -93,7 +94,9 @@ bool PathLocks::lockPaths(const PathSet& paths, const string& waitMsg,
       /* Acquire an exclusive lock. */
       if (!lockFile(fd.get(), ltWrite, false)) {
         if (wait) {
-          if (waitMsg != "") printError(waitMsg);
+          if (waitMsg != "") {
+            LOG(WARNING) << waitMsg;
+          }
           lockFile(fd.get(), ltWrite, true);
         } else {
           /* Failed to lock this path; release all other
@@ -103,7 +106,7 @@ bool PathLocks::lockPaths(const PathSet& paths, const string& waitMsg,
         }
       }
 
-      debug(format("lock acquired on '%1%'") % lockPath);
+      DLOG(INFO) << "lock acquired on '" << lockPath << "'";
 
       /* Check that the lock file hasn't become stale (i.e.,
          hasn't been unlinked). */
@@ -115,7 +118,7 @@ bool PathLocks::lockPaths(const PathSet& paths, const string& waitMsg,
            a lock on a deleted file.  This means that other
            processes may create and acquire a lock on
            `lockPath', and proceed.  So we must retry. */
-        debug(format("open lock file '%1%' has become stale") % lockPath);
+        DLOG(INFO) << "open lock file '" << lockPath << "' has become stale";
       else
         break;
     }
@@ -139,11 +142,11 @@ void PathLocks::unlock() {
   for (auto& i : fds) {
     if (deletePaths) deleteLockFile(i.second, i.first);
 
-    if (close(i.first) == -1)
-      printError(format("error (ignored): cannot close lock file on '%1%'") %
-                 i.second);
+    if (close(i.first) == -1) {
+      LOG(WARNING) << "cannot close lock file on '" << i.second << "'";
+    }
 
-    debug(format("lock released on '%1%'") % i.second);
+    DLOG(INFO) << "lock released on '" << i.second << "'";
   }
 
   fds.clear();
diff --git a/third_party/nix/src/libstore/profiles.cc b/third_party/nix/src/libstore/profiles.cc
index 614153d89d..51379710e2 100644
--- a/third_party/nix/src/libstore/profiles.cc
+++ b/third_party/nix/src/libstore/profiles.cc
@@ -1,5 +1,6 @@
 #include "profiles.hh"
 #include <errno.h>
+#include <glog/logging.h>
 #include <stdio.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -110,10 +111,10 @@ void deleteGeneration(const Path& profile, unsigned int gen) {
 
 static void deleteGeneration2(const Path& profile, unsigned int gen,
                               bool dryRun) {
-  if (dryRun)
-    printInfo(format("would remove generation %1%") % gen);
-  else {
-    printInfo(format("removing generation %1%") % gen);
+  if (dryRun) {
+    LOG(INFO) << "would remove generation " << gen;
+  } else {
+    LOG(INFO) << "removing generation " << gen;
     deleteGeneration(profile, gen);
   }
 }
diff --git a/third_party/nix/src/libstore/references.cc b/third_party/nix/src/libstore/references.cc
index df3ee73fde..5413bfb5cf 100644
--- a/third_party/nix/src/libstore/references.cc
+++ b/third_party/nix/src/libstore/references.cc
@@ -1,4 +1,5 @@
 #include "references.hh"
+#include <glog/logging.h>
 #include <cstdlib>
 #include <map>
 #include "archive.hh"
@@ -32,7 +33,7 @@ static void search(const unsigned char* s, size_t len, StringSet& hashes,
     if (!match) continue;
     string ref((const char*)s + i, refLength);
     if (hashes.find(ref) != hashes.end()) {
-      debug(format("found reference to '%1%' at offset '%2%'") % ref % i);
+      DLOG(INFO) << "found reference to '" << ref << "' at offset " << i;
       seen.insert(ref);
       hashes.erase(ref);
     }
diff --git a/third_party/nix/src/libstore/remote-store.cc b/third_party/nix/src/libstore/remote-store.cc
index 802316dcf3..d041c452a8 100644
--- a/third_party/nix/src/libstore/remote-store.cc
+++ b/third_party/nix/src/libstore/remote-store.cc
@@ -1,6 +1,7 @@
 #include "remote-store.hh"
 #include <errno.h>
 #include <fcntl.h>
+#include <glog/logging.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -13,6 +14,7 @@
 #include "finally.hh"
 #include "globals.hh"
 #include "pool.hh"
+#include "prefork-compat.hh"
 #include "serialise.hh"
 #include "util.hh"
 #include "worker-protocol.hh"
@@ -150,10 +152,14 @@ void RemoteStore::initConnection(Connection& conn) {
 }
 
 void RemoteStore::setOptions(Connection& conn) {
-  conn.to << wopSetOptions << settings.keepFailed << settings.keepGoing
-          << settings.tryFallback << verbosity << settings.maxBuildJobs
-          << settings.maxSilentTime << true
-          << (settings.verboseBuild ? lvlError : lvlVomit)
+  conn.to << wopSetOptions << settings.keepFailed
+          << settings.keepGoing
+          // TODO(tazjin): Remove the verbosity stuff here.
+          << settings.tryFallback << compat::kInfo << settings.maxBuildJobs
+          << settings.maxSilentTime
+          << true
+          // TODO(tazjin): what behaviour does this toggle remotely?
+          << (settings.verboseBuild ? compat::kError : compat::kVomit)
           << 0  // obsolete log type
           << 0  /* obsolete print build trace */
           << settings.buildCores << settings.useSubstitutes;
@@ -194,7 +200,8 @@ struct ConnectionHandle {
   ~ConnectionHandle() {
     if (!daemonException && std::uncaught_exceptions()) {
       handle.markBad();
-      debug("closing daemon connection because of an exception");
+      // TODO(tazjin): are these types of things supposed to be DEBUG?
+      DLOG(INFO) << "closing daemon connection because of an exception";
     }
   }
 
@@ -625,19 +632,29 @@ RemoteStore::Connection::~Connection() {
   }
 }
 
-static Logger::Fields readFields(Source& from) {
-  Logger::Fields fields;
+// TODO(tazjin): these logger fields used to be passed to the JSON
+// logger but I don't care about them, whatever sends them should
+// also be fixed.
+static void ignoreFields(Source& from) {
   size_t size = readInt(from);
+
+  // This ignores the fields simply by reading the data into nowhere.
   for (size_t n = 0; n < size; n++) {
-    auto type = (decltype(Logger::Field::type))readInt(from);
-    if (type == Logger::Field::tInt)
-      fields.push_back(readNum<uint64_t>(from));
-    else if (type == Logger::Field::tString)
-      fields.push_back(readString(from));
-    else
-      throw Error("got unsupported field type %x from Nix daemon", (int)type);
+    auto type_tag = readInt(from);
+
+    switch (type_tag) {
+      case 0:  // previously: 0 ~ Logger::Field::tInt
+        readNum<uint64_t>(from);
+        break;
+
+      case 1:  // previously: 1 ~ Logger::Field::tString
+        readString(from);
+        break;
+
+      default:
+        throw Error("got unsupported field type %x from Nix daemon", type_tag);
+    }
   }
-  return fields;
 }
 
 std::exception_ptr RemoteStore::Connection::processStderr(Sink* sink,
@@ -667,36 +684,52 @@ std::exception_ptr RemoteStore::Connection::processStderr(Sink* sink,
       return std::make_exception_ptr(Error(status, error));
     }
 
-    else if (msg == STDERR_NEXT)
-      printError(chomp(readString(from)));
+    else if (msg == STDERR_NEXT) {
+      LOG(ERROR) << chomp(readString(from));
+    }
 
     else if (msg == STDERR_START_ACTIVITY) {
-      auto act = readNum<ActivityId>(from);
-      auto lvl = (Verbosity)readInt(from);
-      auto type = (ActivityType)readInt(from);
-      auto s = readString(from);
-      auto fields = readFields(from);
-      auto parent = readNum<ActivityId>(from);
-      logger->startActivity(act, lvl, type, s, fields, parent);
+      // Various fields need to be ignored in this case, as the
+      // activity stuff is being removed.
+      readNum<uint64_t>(from);  // used to be ActivityId
+      const auto verbosity = static_cast<compat::Verbosity>(readInt(from));
+      readInt(from);  // activity type
+      const auto msg = readString(from);
+      ignoreFields(from);
+      readNum<uint64_t>(from);  // ActivityId of "parent"
+
+      switch (verbosity) {
+        case compat::kError:
+          LOG(ERROR) << msg;
+          break;
+        case compat::kWarn:
+          LOG(WARNING) << msg;
+          break;
+        case compat::kInfo:
+          LOG(INFO) << msg;
+          break;
+        default:
+          DLOG(INFO) << msg;
+      }
     }
 
     else if (msg == STDERR_STOP_ACTIVITY) {
-      auto act = readNum<ActivityId>(from);
-      logger->stopActivity(act);
+      readNum<uint64_t>(from);  // used to be ActivityId
     }
 
     else if (msg == STDERR_RESULT) {
-      auto act = readNum<ActivityId>(from);
-      auto type = (ResultType)readInt(from);
-      auto fields = readFields(from);
-      logger->result(act, type, fields);
+      readNum<uint64_t>(from);  // ActivityId
+      readInt(from);            // ResultType
+      ignoreFields(from);
     }
 
-    else if (msg == STDERR_LAST)
+    else if (msg == STDERR_LAST) {
       break;
+    }
 
-    else
+    else {
       throw Error("got unknown message type %x from Nix daemon", msg);
+    }
   }
 
   return nullptr;
diff --git a/third_party/nix/src/libstore/sqlite.cc b/third_party/nix/src/libstore/sqlite.cc
index 2f4bfb654c..aa6c15ec15 100644
--- a/third_party/nix/src/libstore/sqlite.cc
+++ b/third_party/nix/src/libstore/sqlite.cc
@@ -1,4 +1,5 @@
 #include "sqlite.hh"
+#include <glog/logging.h>
 #include <sqlite3.h>
 #include <atomic>
 #include "util.hh"
@@ -157,7 +158,7 @@ void handleSQLiteBusy(const SQLiteBusy& e) {
 
   if (now > lastWarned + 10) {
     lastWarned = now;
-    printError("warning: %s", e.what());
+    LOG(ERROR) << e.what();
   }
 
   /* Sleep for a while since retrying the transaction right away
diff --git a/third_party/nix/src/libstore/ssh.cc b/third_party/nix/src/libstore/ssh.cc
index 72ab1cfcf1..6a2eee5965 100644
--- a/third_party/nix/src/libstore/ssh.cc
+++ b/third_party/nix/src/libstore/ssh.cc
@@ -54,8 +54,13 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(
         } else {
           args = {"ssh", host.c_str(), "-x", "-a"};
           addCommonSSHOpts(args);
-          if (socketPath != "") args.insert(args.end(), {"-S", socketPath});
-          if (verbosity >= lvlChatty) args.push_back("-v");
+          if (socketPath != "") {
+            args.insert(args.end(), {"-S", socketPath});
+          }
+          // TODO(tazjin): Abseil verbosity flag
+          /*if (verbosity >= lvlChatty) {
+              args.push_back("-v");
+              }*/
         }
 
         args.push_back(command);
@@ -107,7 +112,7 @@ Path SSHMaster::startMaster() {
                         "-S",  state->socketPath,
                         "-o",  "LocalCommand=echo started",
                         "-o",  "PermitLocalCommand=yes"};
-        if (verbosity >= lvlChatty) args.push_back("-v");
+        // if (verbosity >= lvlChatty) args.push_back("-v");
         addCommonSSHOpts(args);
         execvp(args.begin()->c_str(), stringsToCharPtrs(args).data());
 
diff --git a/third_party/nix/src/libstore/store-api.cc b/third_party/nix/src/libstore/store-api.cc
index d8ee689044..12b9b1def4 100644
--- a/third_party/nix/src/libstore/store-api.cc
+++ b/third_party/nix/src/libstore/store-api.cc
@@ -1,4 +1,5 @@
 #include "store-api.hh"
+#include <glog/logging.h>
 #include <future>
 #include "crypto.hh"
 #include "derivations.hh"
@@ -526,15 +527,16 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
   auto srcUri = srcStore->getUri();
   auto dstUri = dstStore->getUri();
 
-  Activity act(*logger, lvlInfo, actCopyPath,
-               srcUri == "local" || srcUri == "daemon"
-                   ? fmt("copying path '%s' to '%s'", storePath, dstUri)
-                   : dstUri == "local" || dstUri == "daemon"
-                         ? fmt("copying path '%s' from '%s'", storePath, srcUri)
-                         : fmt("copying path '%s' from '%s' to '%s'", storePath,
-                               srcUri, dstUri),
-               {storePath, srcUri, dstUri});
-  PushActivity pact(act.id);
+  if (srcUri == "local" || srcUri == "daemon") {
+    LOG(INFO) << "copying path '" << storePath << "' to '" << dstUri << "'";
+  } else {
+    if (dstUri == "local" || dstUri == "daemon") {
+      LOG(INFO) << "copying path '" << storePath << "' from '" << srcUri << "'";
+    } else {
+      LOG(INFO) << "copying path '" << storePath << "' from '" << srcUri
+                << "' to '" << dstUri << "'";
+    }
+  }
 
   auto info = srcStore->queryPathInfo(storePath);
 
@@ -565,7 +567,6 @@ void copyStorePath(ref<Store> srcStore, ref<Store> dstStore,
         LambdaSink wrapperSink([&](const unsigned char* data, size_t len) {
           sink(data, len);
           total += len;
-          act.progress(total, info->narSize);
         });
         srcStore->narFromPath({storePath}, wrapperSink);
       },
@@ -588,18 +589,13 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore,
 
   if (missing.empty()) return;
 
-  Activity act(*logger, lvlInfo, actCopyPaths,
-               fmt("copying %d paths", missing.size()));
+  LOG(INFO) << "copying " << missing.size() << " paths";
 
   std::atomic<size_t> nrDone{0};
   std::atomic<size_t> nrFailed{0};
   std::atomic<uint64_t> bytesExpected{0};
   std::atomic<uint64_t> nrRunning{0};
 
-  auto showProgress = [&]() {
-    act.progress(nrDone, missing.size(), nrRunning, nrFailed);
-  };
-
   ThreadPool pool;
 
   processGraph<Path>(
@@ -608,14 +604,12 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore,
       [&](const Path& storePath) {
         if (dstStore->isValidPath(storePath)) {
           nrDone++;
-          showProgress();
           return PathSet();
         }
 
         auto info = srcStore->queryPathInfo(storePath);
 
         bytesExpected += info->narSize;
-        act.setExpected(actCopyPath, bytesExpected);
 
         return info->references;
       },
@@ -625,21 +619,17 @@ void copyPaths(ref<Store> srcStore, ref<Store> dstStore,
 
         if (!dstStore->isValidPath(storePath)) {
           MaintainCount<decltype(nrRunning)> mc(nrRunning);
-          showProgress();
           try {
             copyStorePath(srcStore, dstStore, storePath, repair, checkSigs);
           } catch (Error& e) {
             nrFailed++;
             if (!settings.keepGoing) throw e;
-            logger->log(lvlError,
-                        format("could not copy %s: %s") % storePath % e.what());
-            showProgress();
+            LOG(ERROR) << "could not copy " << storePath << ": " << e.what();
             return;
           }
         }
 
         nrDone++;
-        showProgress();
       });
 }
 
@@ -702,9 +692,8 @@ void ValidPathInfo::sign(const SecretKey& secretKey) {
 
 bool ValidPathInfo::isContentAddressed(const Store& store) const {
   auto warn = [&]() {
-    printError(
-        format("warning: path '%s' claims to be content-addressed but isn't") %
-        path);
+    LOG(ERROR) << "warning: path '" << path
+               << "' claims to be content-addressed but isn't";
   };
 
   if (hasPrefix(ca, "text:")) {
@@ -873,7 +862,7 @@ std::list<ref<Store>> getDefaultSubstituters() {
       try {
         stores.push_back(openStore(uri));
       } catch (Error& e) {
-        printError("warning: %s", e.what());
+        LOG(WARNING) << e.what();
       }
     };
 
diff --git a/third_party/nix/src/libutil/meson.build b/third_party/nix/src/libutil/meson.build
index 5fb3e4804b..325a7d33ba 100644
--- a/third_party/nix/src/libutil/meson.build
+++ b/third_party/nix/src/libutil/meson.build
@@ -11,7 +11,8 @@ libutil_src = files(
     join_paths(meson.source_root(), 'src/libutil/serialise.cc'),
     join_paths(meson.source_root(), 'src/libutil/thread-pool.cc'),
     join_paths(meson.source_root(), 'src/libutil/util.cc'),
-    join_paths(meson.source_root(), 'src/libutil/xml-writer.cc'))
+    join_paths(meson.source_root(), 'src/libutil/xml-writer.cc'),
+)
 
 libutil_headers = files(
     join_paths(meson.source_root(), 'src/libutil/affinity.hh'),
@@ -27,13 +28,14 @@ libutil_headers = files(
     join_paths(meson.source_root(), 'src/libutil/lru-cache.hh'),
     join_paths(meson.source_root(), 'src/libutil/monitor-fd.hh'),
     join_paths(meson.source_root(), 'src/libutil/pool.hh'),
+    join_paths(meson.source_root(), 'src/libutil/prefork-compat.hh'),
     join_paths(meson.source_root(), 'src/libutil/ref.hh'),
     join_paths(meson.source_root(), 'src/libutil/serialise.hh'),
     join_paths(meson.source_root(), 'src/libutil/sync.hh'),
     join_paths(meson.source_root(), 'src/libutil/thread-pool.hh'),
     join_paths(meson.source_root(), 'src/libutil/types.hh'),
     join_paths(meson.source_root(), 'src/libutil/util.hh'),
-    join_paths(meson.source_root(), 'src/libutil/xml-writer.hh')
+    join_paths(meson.source_root(), 'src/libutil/xml-writer.hh'),
 )
 
 libutil_dep_list = [
diff --git a/third_party/nix/src/libutil/prefork-compat.hh b/third_party/nix/src/libutil/prefork-compat.hh
new file mode 100644
index 0000000000..ae9c25e539
--- /dev/null
+++ b/third_party/nix/src/libutil/prefork-compat.hh
@@ -0,0 +1,21 @@
+// This file exists to preserve compatibility with the pre-fork
+// version of Nix (2.3.4).
+//
+// During the refactoring, various structures are getting ripped out
+// and replaced with the dummies below while code is being cleaned up.
+
+#ifndef NIX_SRC_LIBUTIL_PREFORK_COMPAT_H_
+#define NIX_SRC_LIBUTIL_PREFORK_COMPAT_H_
+
+namespace nix::compat {
+
+// This is used in remote-store.cc for various things that expect the
+// old logging protocol when talking over the wire. It will be removed
+// hen the worker protocol is redone.
+enum [[deprecated("old logging compat only")]] Verbosity{
+    kError = 0, kWarn, kInfo, kTalkative, kChatty, kDebug, kVomit,
+};
+
+}  // namespace nix::compat
+
+#endif  // NIX_SRC_LIBUTIL_PREFORK_COMPAT_H_