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

@@ -11,7 +11,7 @@ let
     pname = "metadata-agregator";
     version = "0.1.0";
     src = ./.;
-    vendorHash = "sha256-qNNFHRKqGoo/GveSl9+Bm+DkTKDoSQeGtG8p1edmCJk=";
+    vendorHash = "sha256-iRG3hW7lQW1c9vIfpDs110AHeoq7N3KjyvJN9K0Sjos=";
     subPackages = [ "cmd/server" ];
   };
 in
@@ -80,6 +80,11 @@ in
       ${config.outputs.server}/bin/server -config "$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 = {