Organize local infrastructure and Vault secrets by service ownership

backend/notifications/app/run.go

@@ -33,9 +33,9 @@ func Run(ctx context.Context, c Config, logger mlogger.Logger) error {
 	if err != nil {
 		return err
 	}
-	cert, err := tls.LoadX509KeyPair(c.TLSCert, c.TLSKey)
+	options, err := serverOptions(c)
 	if err != nil {
-		return merrors.OpaqueWrap(merrors.ErrInvalidArg, err, "invalid gRPC TLS certificate")
+		return err
 	}
 	client, err := db.ConnectMongo(logger, &c.Database)
 	if err != nil {
@@ -67,7 +67,7 @@ func Run(ctx context.Context, c Config, logger mlogger.Logger) error {
 	for caller, env := range c.Callers {
 		tokens[caller] = os.Getenv(env)
 	}
-	server := grpc.NewServer(grpc.Creds(credentials.NewTLS(&tls.Config{Certificates: []tls.Certificate{cert}, MinVersion: tls.VersionTLS12})), grpc.UnaryInterceptor(transport.Authenticate(tokens)), grpc.MaxRecvMsgSize(128<<10), grpc.MaxConcurrentStreams(64))
+	server := grpc.NewServer(append(options, grpc.UnaryInterceptor(transport.Authenticate(tokens)), grpc.MaxRecvMsgSize(128<<10), grpc.MaxConcurrentStreams(64))...)
 	pb.RegisterNotificationsServiceServer(server, transport.New(svc))
 	listener, err := net.Listen("tcp", c.Listen)
 	if err != nil {
@@ -103,3 +103,15 @@ func Run(ctx context.Context, c Config, logger mlogger.Logger) error {
 	logger.Info("Notifications service stopped")
 	return nil
 }
+
+// An omitted certificate pair uses plaintext gRPC on the private service network.
+func serverOptions(c Config) ([]grpc.ServerOption, error) {
+	if c.TLSCert == "" && c.TLSKey == "" {
+		return nil, nil
+	}
+	cert, err := tls.LoadX509KeyPair(c.TLSCert, c.TLSKey)
+	if err != nil {
+		return nil, merrors.OpaqueWrap(merrors.ErrInvalidArg, err, "invalid gRPC TLS certificate")
+	}
+	return []grpc.ServerOption{grpc.Creds(credentials.NewTLS(&tls.Config{Certificates: []tls.Certificate{cert}, MinVersion: tls.VersionTLS12}))}, nil
+}