4 files changed, 24 insertions, 2 deletions
diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index e756d3377c34..8c2602a701bd 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -614,7 +614,8 @@ HookInstance::HookInstance()
             settings.thisSystem,
             std::to_string(settings.maxSilentTime),
             std::to_string(settings.buildTimeout),
-            std::to_string(verbosity)
+            std::to_string(verbosity),
+            settings.builders
         };
 
         execv(settings.buildHook.get().c_str(), stringsToCharPtrs(args).data());
diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index 25cc3e068ee7..d7a0b86a0889 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -130,6 +130,9 @@ public:
     PathSetting buildHook{this, true, nixLibexecDir + "/nix/build-remote", "build-hook",
         "The path of the helper program that executes builds to remote machines."};
 
+    Setting<std::string> builders{this, "", "builders",
+        "A semicolon-separated list of build machines, in the format of nix.machines."};
+
     Setting<off_t> reservedSize{this, 8 * 1024 * 1024, "gc-reserved-space",
         "Amount of reserved disk space for the garbage collector."};
 
diff --git a/src/libstore/machines.cc b/src/libstore/machines.cc
index 471ce8efb9a2..479ed1432fb5 100644
--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -44,7 +44,7 @@ bool Machine::mandatoryMet(const std::set<string> & features) const {
 
 void parseMachines(const std::string & s, Machines & machines)
 {
-    for (auto line : tokenizeString<std::vector<string>>(s, "\n")) {
+    for (auto line : tokenizeString<std::vector<string>>(s, "\n;")) {
         chomp(line);
         line.erase(std::find(line.begin(), line.end(), '#'), line.end());
         if (line.empty()) continue;
@@ -62,4 +62,20 @@ void parseMachines(const std::string & s, Machines & machines)
     }
 }
 
+Machines getMachines()
+{
+    Machines machines;
+
+    try {
+        parseMachines(readFile(getEnv("NIX_REMOTE_SYSTEMS", settings.nixConfDir + "/machines")), machines);
+    } catch (const SysError & e) {
+        if (e.errNo != ENOENT)
+            throw;
+    }
+
+    parseMachines(settings.builders, machines);
+
+    return machines;
+}
+
 }
diff --git a/src/libstore/machines.hh b/src/libstore/machines.hh
index 96c4bd81a462..e0455742844b 100644
--- a/src/libstore/machines.hh
+++ b/src/libstore/machines.hh
@@ -32,4 +32,6 @@ typedef std::vector<Machine> Machines;
 
 void parseMachines(const std::string & s, Machines & machines);
 
+Machines getMachines();
+
 }