fix kubelet flushlogs not working together with exit

cmd/kubelet/app/server.go

@@ -116,6 +116,7 @@ func NewKubeletCommand() *cobra.Command {
 	cleanFlagSet := pflag.NewFlagSet(componentKubelet, pflag.ContinueOnError)
 	cleanFlagSet.SetNormalizeFunc(cliflag.WordSepNormalizeFunc)
 	kubeletFlags := options.NewKubeletFlags()
+
 	kubeletConfig, err := options.NewKubeletConfiguration()
 	// programmer error
 	if err != nil {
@@ -152,31 +153,25 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 		// DisableFlagParsing=true provides the full set of flags passed to the kubelet in the
 		// `args` arg to Run, without Cobra's interference.
 		DisableFlagParsing: true,
-		Run: func(cmd *cobra.Command, args []string) {
+		RunE: func(cmd *cobra.Command, args []string) error {
 			// initial flag parse, since we disable cobra's flag parsing
 			if err := cleanFlagSet.Parse(args); err != nil {
-				klog.ErrorS(err, "Failed to parse kubelet flag")
-				cmd.Usage()
-				os.Exit(1)
+				return fmt.Errorf("failed to parse kubelet flag: %v", err)
 			}
 
 			// check if there are non-flag arguments in the command line
 			cmds := cleanFlagSet.Args()
 			if len(cmds) > 0 {
-				klog.ErrorS(nil, "Unknown command", "command", cmds[0])
-				cmd.Usage()
-				os.Exit(1)
+				return fmt.Errorf("unknown command %+s", cmds[0])
 			}
 
 			// short-circuit on help
 			help, err := cleanFlagSet.GetBool("help")
 			if err != nil {
-				klog.InfoS(`"help" flag is non-bool, programmer error, please correct`)
-				os.Exit(1)
+				return errors.New(`"help" flag is non-bool, programmer error, please correct`)
 			}
 			if help {
-				cmd.Help()
-				return
+				return cmd.Help()
 			}
 
 			// short-circuit on verflag
@@ -185,14 +180,12 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 
 			// set feature gates from initial flags-based config
 			if err := utilfeature.DefaultMutableFeatureGate.SetFromMap(kubeletConfig.FeatureGates); err != nil {
-				klog.ErrorS(err, "Failed to set feature gates from initial flags-based config")
-				os.Exit(1)
+				return fmt.Errorf("failed to set feature gates from initial flags-based config: %v", err)
 			}
 
 			// validate the initial KubeletFlags
 			if err := options.ValidateKubeletFlags(kubeletFlags); err != nil {
-				klog.ErrorS(err, "Failed to validate kubelet flags")
-				os.Exit(1)
+				return fmt.Errorf("failed to validate kubelet flags: %v", err)
 			}
 
 			if kubeletFlags.ContainerRuntime == "remote" && cleanFlagSet.Changed("pod-infra-container-image") {
@@ -203,28 +196,24 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 			if configFile := kubeletFlags.KubeletConfigFile; len(configFile) > 0 {
 				kubeletConfig, err = loadConfigFile(configFile)
 				if err != nil {
-					klog.ErrorS(err, "Failed to load kubelet config file", "path", configFile)
-					os.Exit(1)
+					return fmt.Errorf("failed to load kubelet config file, error: %v, path: %s", err, configFile)
 				}
 				// We must enforce flag precedence by re-parsing the command line into the new object.
 				// This is necessary to preserve backwards-compatibility across binary upgrades.
 				// See issue #56171 for more details.
 				if err := kubeletConfigFlagPrecedence(kubeletConfig, args); err != nil {
-					klog.ErrorS(err, "Failed to precedence kubeletConfigFlag")
-					os.Exit(1)
+					return fmt.Errorf("failed to precedence kubeletConfigFlag: %v", err)
 				}
 				// update feature gates based on new config
 				if err := utilfeature.DefaultMutableFeatureGate.SetFromMap(kubeletConfig.FeatureGates); err != nil {
-					klog.ErrorS(err, "Failed to set feature gates from initial flags-based config")
-					os.Exit(1)
+					return fmt.Errorf("failed to set feature gates from initial flags-based config: %v", err)
 				}
 			}
 
 			// We always validate the local configuration (command line + config file).
 			// This is the default "last-known-good" config for dynamic config, and must always remain valid.
 			if err := kubeletconfigvalidation.ValidateKubeletConfiguration(kubeletConfig); err != nil {
-				klog.ErrorS(err, "Failed to validate kubelet configuration", "path", kubeletConfig)
-				os.Exit(1)
+				return fmt.Errorf("failed to validate kubelet configuration, error: %v, path: %s", err, kubeletConfig)
 			}
 
 			if (kubeletConfig.KubeletCgroups != "" && kubeletConfig.KubeReservedCgroup != "") && (strings.Index(kubeletConfig.KubeletCgroups, kubeletConfig.KubeReservedCgroup) != 0) {
@@ -244,17 +233,15 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 						return kubeletConfigFlagPrecedence(kc, args)
 					})
 				if err != nil {
-					klog.ErrorS(err, "Failed to bootstrap a configuration controller", "dynamicConfigDir", dynamicConfigDir)
-					os.Exit(1)
+					return fmt.Errorf("failed to bootstrap a configuration controller, error: %v, dynamicConfigDir: %s", err, dynamicConfigDir)
 				}
 				// If we should just use our existing, local config, the controller will return a nil config
 				if dynamicKubeletConfig != nil {
 					kubeletConfig = dynamicKubeletConfig
 					// Note: flag precedence was already enforced in the controller, prior to validation,
 					// by our above transform function. Now we simply update feature gates from the new config.
 					if err := utilfeature.DefaultMutableFeatureGate.SetFromMap(kubeletConfig.FeatureGates); err != nil {
-						klog.ErrorS(err, "Failed to set feature gates from initial flags-based config")
-						os.Exit(1)
+						return fmt.Errorf("failed to set feature gates from initial flags-based config: %v", err)
 					}
 				}
 			}
@@ -276,8 +263,7 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 			// use kubeletServer to construct the default KubeletDeps
 			kubeletDeps, err := UnsecuredDependencies(kubeletServer, utilfeature.DefaultFeatureGate)
 			if err != nil {
-				klog.ErrorS(err, "Failed to construct kubelet dependencies")
-				os.Exit(1)
+				return fmt.Errorf("failed to construct kubelet dependencies: %v", err)
 			}
 
 			// add the kubelet config controller to kubeletDeps
@@ -298,10 +284,7 @@ HTTP server: The kubelet can also listen for HTTP and respond to a simple API
 			klog.V(5).InfoS("KubeletConfiguration", "configuration", kubeletServer.KubeletConfiguration)
 
 			// run the kubelet
-			if err := Run(ctx, kubeletServer, kubeletDeps, utilfeature.DefaultFeatureGate); err != nil {
-				klog.ErrorS(err, "Failed to run kubelet")
-				os.Exit(1)
-			}
+			return Run(ctx, kubeletServer, kubeletDeps, utilfeature.DefaultFeatureGate)
 		},
 	}