6 files changed, 133 insertions, 1 deletions
diff --git a/third_party/nix/src/libstore/derivations.cc b/third_party/nix/src/libstore/derivations.cc
index 59b2a505a307..419fc584f1fe 100644
--- a/third_party/nix/src/libstore/derivations.cc
+++ b/third_party/nix/src/libstore/derivations.cc
@@ -30,6 +30,28 @@ void DerivationOutput::parseHashInfo(bool& recursive, Hash& hash) const {
   hash = Hash(this->hash, hashType);
 }
 
+BasicDerivation BasicDerivation::from_proto(
+    const nix::proto::Derivation* proto_derivation, const nix::Store* store) {
+  BasicDerivation result;
+  result.platform = proto_derivation->platform();
+  result.builder = proto_derivation->builder().path();
+  store->assertStorePath(result.builder);
+
+  result.outputs.insert(proto_derivation->outputs().begin(),
+                        proto_derivation->outputs().end());
+
+  result.inputSrcs.insert(proto_derivation->input_sources().paths().begin(),
+                          proto_derivation->input_sources().paths().end());
+
+  result.args.insert(result.args.end(), proto_derivation->args().begin(),
+                     proto_derivation->args().end());
+
+  result.env.insert(proto_derivation->env().begin(),
+                    proto_derivation->env().end());
+
+  return result;
+}
+
 Path BasicDerivation::findOutput(const std::string& id) const {
   auto i = outputs.find(id);
   if (i == outputs.end()) {
diff --git a/third_party/nix/src/libstore/derivations.hh b/third_party/nix/src/libstore/derivations.hh
index 7574aa90c2c4..d8a5dbf09246 100644
--- a/third_party/nix/src/libstore/derivations.hh
+++ b/third_party/nix/src/libstore/derivations.hh
@@ -2,6 +2,7 @@
 
 #include <map>
 
+#include "libproto/worker.pb.h"
 #include "libstore/store-api.hh"
 #include "libutil/hash.hh"
 #include "libutil/types.hh"
@@ -18,20 +19,31 @@ struct DerivationOutput {
   std::string hashAlgo; /* hash used for expected hash computation */
   std::string hash;     /* expected hash, may be null */
   DerivationOutput() {}
+  // TODO(grfn): Make explicit
   DerivationOutput(Path path, std::string hashAlgo, std::string hash) {
     this->path = path;
     this->hashAlgo = hashAlgo;
     this->hash = hash;
   }
+
+  explicit DerivationOutput(
+      const nix::proto::Derivation_DerivationOutput& proto_derivation_output)
+      : path(proto_derivation_output.path().path()),
+        hashAlgo(proto_derivation_output.hash_algo()),
+        hash(proto_derivation_output.hash()) {}
+
   void parseHashInfo(bool& recursive, Hash& hash) const;
 };
 
+// TODO(grfn): change to absl::flat_hash_map
 typedef std::map<std::string, DerivationOutput> DerivationOutputs;
 
 /* For inputs that are sub-derivations, we specify exactly which
    output IDs we are interested in. */
+// TODO(grfn): change to absl::flat_hash_map
 typedef std::map<Path, StringSet> DerivationInputs;
 
+// TODO(grfn): change to absl::flat_hash_map
 typedef std::map<std::string, std::string> StringPairs;
 
 struct BasicDerivation {
@@ -42,6 +54,13 @@ struct BasicDerivation {
   Strings args;
   StringPairs env;
 
+  BasicDerivation(){};
+
+  // Convert the given proto derivation to a BasicDerivation in the given
+  // nix::Store.
+  static BasicDerivation from_proto(
+      const nix::proto::Derivation* proto_derivation, const nix::Store* store);
+
   virtual ~BasicDerivation(){};
 
   /* Return the path corresponding to the output identifier `id' in
diff --git a/third_party/nix/src/libstore/store-api.cc b/third_party/nix/src/libstore/store-api.cc
index dd1b199d927d..47f85e6e2610 100644
--- a/third_party/nix/src/libstore/store-api.cc
+++ b/third_party/nix/src/libstore/store-api.cc
@@ -18,6 +18,50 @@
 
 namespace nix {
 
+std::optional<BuildMode> build_mode_from(nix::proto::BuildMode mode) {
+  switch (mode) {
+    case nix::proto::BuildMode::Normal:
+      return BuildMode::bmNormal;
+    case nix::proto::BuildMode::Repair:
+      return BuildMode::bmRepair;
+    case nix::proto::BuildMode::Check:
+      return BuildMode::bmCheck;
+    default:
+      return {};
+  }
+}
+
+nix::proto::BuildStatus BuildResult::status_to_proto() {
+  switch (status) {
+    case BuildResult::Status::Built:
+      return proto::BuildStatus::Built;
+    case BuildResult::Status::Substituted:
+      return proto::BuildStatus::Substituted;
+    case BuildResult::Status::AlreadyValid:
+      return proto::BuildStatus::AlreadyValid;
+    case BuildResult::Status::PermanentFailure:
+      return proto::BuildStatus::PermanentFailure;
+    case BuildResult::Status::InputRejected:
+      return proto::BuildStatus::InputRejected;
+    case BuildResult::Status::OutputRejected:
+      return proto::BuildStatus::OutputRejected;
+    case BuildResult::Status::TransientFailure:
+      return proto::BuildStatus::TransientFailure;
+    case BuildResult::Status::CachedFailure:
+      return proto::BuildStatus::CachedFailure;
+    case BuildResult::Status::TimedOut:
+      return proto::BuildStatus::TimedOut;
+    case BuildResult::Status::MiscFailure:
+      return proto::BuildStatus::MiscFailure;
+    case BuildResult::Status::DependencyFailed:
+      return proto::BuildStatus::DependencyFailed;
+    case BuildResult::Status::LogLimitExceeded:
+      return proto::BuildStatus::LogLimitExceeded;
+    case BuildResult::Status::NotDeterministic:
+      return proto::BuildStatus::NotDeterministic;
+  }
+}
+
 bool Store::isInStore(const Path& path) const {
   return isInDir(path, storeDir);
 }
diff --git a/third_party/nix/src/libstore/store-api.hh b/third_party/nix/src/libstore/store-api.hh
index c6f8d75b67e2..f5076e458d7a 100644
--- a/third_party/nix/src/libstore/store-api.hh
+++ b/third_party/nix/src/libstore/store-api.hh
@@ -8,6 +8,7 @@
 #include <unordered_map>
 #include <unordered_set>
 
+#include "libproto/worker.pb.h"
 #include "libstore/crypto.hh"
 #include "libstore/globals.hh"
 #include "libutil/config.hh"
@@ -181,6 +182,10 @@ typedef std::list<ValidPathInfo> ValidPathInfos;
 
 enum BuildMode { bmNormal, bmRepair, bmCheck };
 
+// Convert the proto version of a `nix::proto::BuildMode` to its corresponding
+// nix `BuildMode`
+std::optional<BuildMode> build_mode_from(nix::proto::BuildMode mode);
+
 struct BuildResult {
   /* Note: don't remove status codes, and only add new status codes
      at the end of the list, to prevent client/server
@@ -218,6 +223,10 @@ struct BuildResult {
   bool success() {
     return status == Built || status == Substituted || status == AlreadyValid;
   }
+
+  // Convert the status of this `BuildResult` to its corresponding
+  // `nix::proto::BuildStatus`
+  nix::proto::BuildStatus status_to_proto();
 };
 
 class Store : public std::enable_shared_from_this<Store>, public Config {
diff --git a/third_party/nix/src/nix-daemon/nix-daemon-proto.cc b/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
index 1ba440522a75..26ae538f29ad 100644
--- a/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
+++ b/third_party/nix/src/nix-daemon/nix-daemon-proto.cc
@@ -6,11 +6,13 @@
 
 #include "libproto/worker.grpc.pb.h"
 #include "libproto/worker.pb.h"
+#include "libstore/derivations.hh"
 #include "libstore/store-api.hh"
 
 namespace nix::daemon {
 
 using ::grpc::Status;
+using ::nix::proto::BuildStatus;
 using ::nix::proto::PathInfo;
 using ::nix::proto::StorePath;
 using ::nix::proto::StorePaths;
@@ -204,6 +206,27 @@ class WorkerServiceImpl final : public WorkerService::Service {
     return Status::OK;
   }
 
+  Status BuildDerivation(
+      grpc::ServerContext* context,
+      const nix::proto::BuildDerivationRequest* request,
+      nix::proto::BuildDerivationResponse* response) override {
+    auto drv_path = request->drv_path().path();
+    store_->assertStorePath(drv_path);
+    auto drv = BasicDerivation::from_proto(&request->derivation(), store_);
+
+    auto build_mode = nix::build_mode_from(request->build_mode());
+    if (!build_mode) {
+      return Status(grpc::StatusCode::INTERNAL, "Invalid build mode");
+    }
+
+    auto res = store_->buildDerivation(drv_path, drv, *build_mode);
+
+    response->set_status(res.status_to_proto());
+    response->set_error_message(res.errorMsg);
+
+    return Status::OK;
+  }
+
   Status QueryMissing(grpc::ServerContext* context, const StorePaths* request,
                       nix::proto::QueryMissingResponse* response) override {
     std::set<Path> targets;
diff --git a/third_party/nix/src/proto/worker.proto b/third_party/nix/src/proto/worker.proto
index 8e629da70967..3dd83d9988f7 100644
--- a/third_party/nix/src/proto/worker.proto
+++ b/third_party/nix/src/proto/worker.proto
@@ -288,10 +288,25 @@ message VerifyStoreResponse {
   bool errors = 1;
 }
 
+message Derivation {
+  message DerivationOutput {
+    StorePath path = 1;
+    string hash_algo = 2;
+    bytes hash = 3;
+  }
+  map<string, DerivationOutput> outputs = 1;
+  StorePaths input_sources = 2;
+  string platform = 3;
+  StorePath builder = 4;
+  repeated string args = 5;
+  map<string, string> env = 6;
+}
+
 message BuildDerivationRequest {
   // Only used for informational purposes.
   StorePath drv_path = 1;
-  BuildMode build_mode = 2;
+  Derivation derivation = 2;
+  BuildMode build_mode = 3;
 }
 
 message BuildDerivationResponse {