Add readiness probe to devenv

cmd/server/main.go

@@ -14,6 +14,8 @@ import (
 	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/rs/zerolog/log"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/health"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
 	"google.golang.org/grpc/reflection"
 
 	"github.com/metadata-agregator/internal/config"
@@ -67,6 +69,7 @@ func main() {
 		),
 	)
 	metadatav1.RegisterMetadataServiceServer(grpcServer, server.NewMetadataServer(services))
+	healthpb.RegisterHealthServer(grpcServer, health.NewServer())
 	reflection.Register(grpcServer)
 
 	srvMetrics.InitializeMetrics(grpcServer)

devenv.nix

@@ -5,6 +5,16 @@
   inputs,
   ...
 }:
+
+let
+  server = pkgs.buildGoModule {
+    pname = "metadata-agregator";
+    version = "0.1.0";
+    src = ./.;
+    vendorHash = "sha256-iRG3hW7lQW1c9vIfpDs110AHeoq7N3KjyvJN9K0Sjos=";
+    subPackages = [ "cmd/server" ];
+  };
+in
 {
   languages.go.enable = true;
 
@@ -59,4 +69,25 @@
       GRANT ALL ON SCHEMA public TO agregator;
     '';
   };
+
+  processes.metadata-agregator = {
+    exec = ''
+      export DATABASE_URL="postgresql://agregator:agregator@localhost/metadata_agregator?host=${config.env.PGHOST}"
+      cat > "$DEVENV_RUNTIME/metadata-config.yaml" <<'YAML'
+      server:
+        port: 50053
+      YAML
+      ${config.outputs.server}/bin/server -config "$DEVENV_RUNTIME/metadata-config.yaml"
+    '';
+    after = [ "devenv:processes:postgres" ];
+    # Probes the standard gRPC Health Checking Protocol (cmd/server/main.go
+    # registers google.golang.org/grpc/health + reflection). Port matches
+    # server.port in the YAML above. SERVING means the gRPC server is
+    # accepting connections; postgres readiness is already gated by `after`.
+    ready.exec = "grpcurl -plaintext -max-time 2 localhost:50053 grpc.health.v1.Health/Check | grep -q SERVING";
+  };
+
+  outputs = {
+    inherit server;
+  };
 }