Improve logging and set exit code according to the exit status

cmd/agent/run.go

@@ -97,16 +97,21 @@ func run(ctx context.Context) error {
 	defer registrator.ReleaseWaiters()
 
 	castailog.SetupLogExporter(registrator, remoteLogger, localLog, castaiClient, &loggingConfig)
-	// to invoke exit handlers set up in castailog.SetupLogExporter
-	defer logrus.Exit(0)
 
 	clusterIDHandler := func(clusterID string) {
 		loggingConfig.ClusterID = clusterID
 		log.Data["cluster_id"] = clusterID
 		registrator.ReleaseWaiters()
 	}
 
-	return runAgentMode(ctx, castaiClient, log, cfg, clusterIDHandler)
+	err = runAgentMode(ctx, castaiClient, log, cfg, clusterIDHandler)
+	if err != nil {
+		// it is necessary to log error because invoking of logrus exit handlers will terminate the process using os.Exit()
+		// error handling in cobra ("github.com/spf13/cobra") won't be able to log this error
+		remoteLogger.Error(err)
+	}
+	defer castailog.InvokeLogrusExitHandlers(err)
+	return err
 }
 
 func runAgentMode(ctx context.Context, castaiclient castai.Client, log *logrus.Entry, cfg config.Config, clusterIDChanged func(clusterID string)) error {

cmd/monitor/run.go

@@ -50,16 +50,20 @@ func run(ctx context.Context) error {
 	defer registrator.ReleaseWaiters()
 
 	castailog.SetupLogExporter(registrator, remoteLogger, localLog, castaiClient, &loggingConfig)
-	// to invoke exit handlers set up in castailog.SetupLogExporter
-	defer logrus.Exit(0)
-
 	clusterIDHandler := func(clusterID string) {
 		loggingConfig.ClusterID = clusterID
 		log.Data["cluster_id"] = clusterID
 		registrator.ReleaseWaiters()
 	}
 
-	return runMonitorMode(ctx, log, cfg, clusterIDHandler)
+	err = runMonitorMode(ctx, log, cfg, clusterIDHandler)
+	if err != nil {
+		// it is necessary to log error because invoking of logrus exit handlers will terminate the process using os.Exit()
+		// error handling in cobra ("github.com/spf13/cobra") won't be able to log this error
+		remoteLogger.Error(err)
+	}
+	defer castailog.InvokeLogrusExitHandlers(err)
+	return err
 }
 
 func runMonitorMode(ctx context.Context, log *logrus.Entry, cfg config.Config, clusterIDChanged func(clusterID string)) error {

pkg/log/exporter.go

@@ -105,3 +105,14 @@ func (ex *exporter) sendLogEvent(clusterID string, e *logrus.Entry) {
 		ex.localLog.Errorf("failed to send logs: %v", err)
 	}
 }
+
+// InvokeLogrusExitHandlers invokes exit handlers set up in SetupLogExporter
+// The handlers are also invoked when any Fatal log entry is made.
+// logrus.Exit runs all the Logrus exit handlers and then terminates the program using os.Exit(code)
+func InvokeLogrusExitHandlers(err error) {
+	if err != nil {
+		logrus.Exit(1)
+	} else {
+		logrus.Exit(0)
+	}
+}