initialized the prometheus client into two steps

Signed-off-by: Augustin Husson <husson.augustin@gmail.com>

Author: Nexucis

langserver/general.go

@@ -58,17 +58,32 @@ func (s *server) Initialize(_ context.Context, _ *protocol.ParamInitialize) (*pr
 
 // Initialized receives a confirmation by the client that the connection has been initialized
 // required by the protocol.Server interface.
-func (s *server) Initialized(_ context.Context, _ *protocol.InitializedParams) (err error) {
+func (s *server) Initialized(ctx context.Context, _ *protocol.InitializedParams) error {
 	s.stateMu.Lock()
 	defer s.stateMu.Unlock()
 
 	if s.state != serverInitializing {
 		return errors.New("cannot initialize server: wrong server state")
 	}
 
-	s.state = serverInitialized
+	if len(s.prometheusURL) > 0 {
+		if err := s.connectPrometheus(s.prometheusURL); err != nil {
+			// nolint: errcheck
+			s.client.LogMessage(ctx, &protocol.LogMessageParams{
+				Type:    protocol.Info,
+				Message: err.Error(),
+			})
+		}
+	} else {
+		// nolint: errcheck
+		s.client.LogMessage(ctx, &protocol.LogMessageParams{
+			Type:    protocol.Info,
+			Message: "No Prometheus",
+		})
+	}
 
-	return err
+	s.state = serverInitialized
+	return nil
 }
 
 // Shutdown receives a call from the client to shutdown the connection

langserver/server.go

@@ -59,6 +59,10 @@ type server struct {
 	cache cache.DocumentCache
 
 	metadataService promClient.MetadataService
+	// prometheusURL is the url to the prometheus datasource
+	// this attribute shouldn't be used or set by other things except the configuration and the method server#Initialized
+	// it shouldn't be used basically when the server is used as an HTTP server
+	prometheusURL string
 
 	lifetime context.Context
 	exit     func()
@@ -130,7 +134,9 @@ func ServerFromStream(ctx context.Context, stream jsonrpc2.Stream, conf *config.
 
 	s.lifetime, s.exit = context.WithCancel(ctx)
 
-	prometheusClient, err := promClient.NewClient(conf.PrometheusURL)
+	// In order to have an error message in the IDE/editor, we are going to set the prometheusURL in the method server#Initialized.
+	s.prometheusURL = conf.PrometheusURL
+	prometheusClient, err := promClient.NewClient("")
 	if err != nil {
 		// nolint: errcheck
 		s.client.ShowMessage(s.lifetime, &protocol.ShowMessageParams{