added json logging support in karmada-agent (#6442)

* added json logging support in karmada-agent

Signed-off-by: Yifan <[email protected]>

* flush logs at the end of the main function of karmada-agent

Signed-off-by: Yifan <[email protected]>

---------

Signed-off-by: Yifan <[email protected]>

Author: zclyne

artifacts/agent/karmada-agent.yaml

@@ -39,6 +39,7 @@ spec:
             - --metrics-bind-address=$(POD_IP):8080
             - --health-probe-bind-address=$(POD_IP):10357
             - --feature-gates=CustomizedClusterResourceModeling=true,MultiClusterService=true
+            - --logging-format=json
             - --v=4
           livenessProbe:
             httpGet:

cmd/agent/app/agent.go

@@ -30,6 +30,8 @@ import (
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/util/flowcontrol"
 	cliflag "k8s.io/component-base/cli/flag"
+	"k8s.io/component-base/logs"
+	logsv1 "k8s.io/component-base/logs/api/v1"
 	"k8s.io/component-base/term"
 	"k8s.io/klog/v2"
 	controllerruntime "sigs.k8s.io/controller-runtime"
@@ -72,13 +74,32 @@ import (
 
 // NewAgentCommand creates a *cobra.Command object with default parameters
 func NewAgentCommand(ctx context.Context) *cobra.Command {
+	logConfig := logsv1.NewLoggingConfiguration()
+	fss := cliflag.NamedFlagSets{}
+
+	// Set klog flags
+	logsFlagSet := fss.FlagSet("logs")
+	logs.AddFlags(logsFlagSet, logs.SkipLoggingConfigurationFlags())
+	logsv1.AddFlags(logConfig, logsFlagSet)
+	klogflag.Add(logsFlagSet)
+
+	genericFlagSet := fss.FlagSet("generic")
+	genericFlagSet.AddGoFlagSet(flag.CommandLine)
 	opts := options.NewOptions()
+	opts.AddFlags(genericFlagSet, controllers.ControllerNames())
 
 	cmd := &cobra.Command{
 		Use: names.KarmadaAgentComponentName,
 		Long: `The karmada-agent is the agent of member clusters. It can register a specific cluster to the Karmada control
 plane and sync manifests from the Karmada control plane to the member cluster. In addition, it also syncs the status of member
 cluster and manifests to the Karmada control plane.`,
+		PersistentPreRunE: func(_ *cobra.Command, _ []string) error {
+			if err := logsv1.ValidateAndApply(logConfig, features.FeatureGate); err != nil {
+				return err
+			}
+			logs.InitLogs()
+			return nil
+		},
 		RunE: func(_ *cobra.Command, _ []string) error {
 			// validate options
 			if errs := opts.Validate(); len(errs) != 0 {
@@ -99,16 +120,6 @@ cluster and manifests to the Karmada control plane.`,
 		},
 	}
 
-	fss := cliflag.NamedFlagSets{}
-
-	genericFlagSet := fss.FlagSet("generic")
-	genericFlagSet.AddGoFlagSet(flag.CommandLine)
-	opts.AddFlags(genericFlagSet, controllers.ControllerNames())
-
-	// Set klog flags
-	logsFlagSet := fss.FlagSet("logs")
-	klogflag.Add(logsFlagSet)
-
 	cmd.AddCommand(sharedcommand.NewCmdVersion(names.KarmadaAgentComponentName))
 	cmd.Flags().AddFlagSet(genericFlagSet)
 	cmd.Flags().AddFlagSet(logsFlagSet)

cmd/agent/main.go

@@ -20,6 +20,7 @@ import (
 	"os"
 
 	"k8s.io/component-base/cli"
+	"k8s.io/component-base/logs"
 	_ "k8s.io/component-base/logs/json/register" // for JSON log format registration
 	"k8s.io/klog/v2"
 	controllerruntime "sigs.k8s.io/controller-runtime"
@@ -37,5 +38,7 @@ func main() {
 	controllerruntime.SetLogger(klog.Background())
 	cmd := app.NewAgentCommand(ctx)
 	code := cli.Run(cmd)
+	// Ensure any buffered log entries are flushed
+	logs.FlushLogs()
 	os.Exit(code)
 }