Fix gRPC health checks and add API Gateway Consul registration

- Fix gRPC health checks: Set serving status for default service (empty string) in all services
  - Consul checks the default service by default, not specific service names
  - All services now set both default and specific service status to SERVING

- Update Consul registration logic to automatically detect HTTP vs gRPC services
  - HTTP services (API Gateway) use HTTP health checks
  - gRPC services use gRPC health checks
  - Detection based on service tags and metadata

- Add API Gateway Consul registration
  - Register with Docker service name in Docker environment
  - Use HTTP health checks for API Gateway
  - Proper host/port configuration handling

- Add API Gateway HTTP-to-gRPC handlers
  - Implement service-specific handlers for Auth and Identity services
  - Translate HTTP requests to gRPC calls
  - Map gRPC error codes to HTTP status codes

cmd/api-gateway/main.go

@@ -58,14 +58,25 @@ func main() {
 			}
 			gateway.SetupRoutes(srv.Router())
 
-			// Register with Consul
+			// Determine port and host for registration
 			gatewayPort := cfg.GetInt("gateway.port")
 			if gatewayPort == 0 {
-				gatewayPort = 8080
+				gatewayPort = cfg.GetInt("server.port")
+				if gatewayPort == 0 {
+					gatewayPort = 8080
+				}
 			}
+
+			// In Docker, always use the Docker service name for health checks
+			// Consul (also in Docker) needs to reach the service via Docker DNS
 			gatewayHost := cfg.GetString("gateway.host")
-			if gatewayHost == "" {
-				gatewayHost = "localhost"
+			if os.Getenv("ENVIRONMENT") == "production" || os.Getenv("DOCKER") == "true" {
+				gatewayHost = "api-gateway" // Docker service name - required for Consul health checks
+			} else if gatewayHost == "" {
+				gatewayHost = cfg.GetString("server.host")
+				if gatewayHost == "" || gatewayHost == "0.0.0.0" {
+					gatewayHost = "localhost" // Local development
+				}
 			}
 
 			serviceInstance := &registry.ServiceInstance{
@@ -75,7 +86,8 @@ func main() {
 				Port:    gatewayPort,
 				Tags:    []string{"gateway", "http"},
 				Metadata: map[string]string{
-					"version": "1.0.0",
+					"version":  "1.0.0",
+					"protocol": "http",
 				},
 			}
 

cmd/audit-service/audit_service_fx.go

@@ -324,6 +324,9 @@ func provideAuditService() fx.Option {
 			// Register health service
 			healthServer := health.NewServer()
 			grpc_health_v1.RegisterHealthServer(grpcServer, healthServer)
+			// Set serving status for the default service (empty string) - this is what Consul checks
+			healthServer.SetServingStatus("", grpc_health_v1.HealthCheckResponse_SERVING)
+			// Also set for the specific service name
 			healthServer.SetServingStatus("audit.v1.AuditService", grpc_health_v1.HealthCheckResponse_SERVING)
 
 			// Register reflection for grpcurl

cmd/auth-service/auth_service_fx.go

@@ -406,6 +406,9 @@ func provideAuthService() fx.Option {
 			// Register health service
 			healthServer := health.NewServer()
 			grpc_health_v1.RegisterHealthServer(grpcServer, healthServer)
+			// Set serving status for the default service (empty string) - this is what Consul checks
+			healthServer.SetServingStatus("", grpc_health_v1.HealthCheckResponse_SERVING)
+			// Also set for the specific service name
 			healthServer.SetServingStatus("auth.v1.AuthService", grpc_health_v1.HealthCheckResponse_SERVING)
 
 			// Register reflection for grpcurl

cmd/authz-service/authz_service_fx.go

@@ -271,6 +271,9 @@ func provideAuthzService() fx.Option {
 			// Register health service
 			healthServer := health.NewServer()
 			grpc_health_v1.RegisterHealthServer(grpcServer, healthServer)
+			// Set serving status for the default service (empty string) - this is what Consul checks
+			healthServer.SetServingStatus("", grpc_health_v1.HealthCheckResponse_SERVING)
+			// Also set for the specific service name
 			healthServer.SetServingStatus("authz.v1.AuthzService", grpc_health_v1.HealthCheckResponse_SERVING)
 
 			// Register reflection for grpcurl

cmd/identity-service/identity_service_fx.go

@@ -418,6 +418,9 @@ func provideIdentityService() fx.Option {
 			// Register health service
 			healthServer := health.NewServer()
 			grpc_health_v1.RegisterHealthServer(grpcServer, healthServer)
+			// Set serving status for the default service (empty string) - this is what Consul checks
+			healthServer.SetServingStatus("", grpc_health_v1.HealthCheckResponse_SERVING)
+			// Also set for the specific service name
 			healthServer.SetServingStatus("identity.v1.IdentityService", grpc_health_v1.HealthCheckResponse_SERVING)
 
 			// Register reflection for grpcurl