cmd: introduce default kubeconfig path

cmd/kperf/commands/runner/runner.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 
 	"github.com/Azure/kperf/api/types"
+	"github.com/Azure/kperf/cmd/kperf/commands/utils"
 	"github.com/Azure/kperf/metrics"
 	"github.com/Azure/kperf/request"
 
@@ -32,6 +33,7 @@ var runCommand = cli.Command{
 		cli.StringFlag{
 			Name:  "kubeconfig",
 			Usage: "Path to the kubeconfig file",
+			Value: utils.DefaultKubeConfigPath,
 		},
 		cli.IntFlag{
 			Name:  "client",

cmd/kperf/commands/runnergroup/root.go

@@ -1,6 +1,8 @@
 package runnergroup
 
 import (
+	"github.com/Azure/kperf/cmd/kperf/commands/utils"
+
 	"github.com/urfave/cli"
 )
 
@@ -13,6 +15,7 @@ var Command = cli.Command{
 		cli.StringFlag{
 			Name:  "kubeconfig",
 			Usage: "Path to the kubeconfig file",
+			Value: utils.DefaultKubeConfigPath,
 		},
 	},
 	Subcommands: []cli.Command{

cmd/kperf/commands/utils/helper.go

@@ -2,9 +2,24 @@ package utils
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
+
+	"k8s.io/client-go/util/homedir"
 )
 
+// DefaultKubeConfigPath is default kubeconfig path if there is home dir.
+var DefaultKubeConfigPath string
+
+func init() {
+	if !inCluster() {
+		if home := homedir.HomeDir(); home != "" {
+			DefaultKubeConfigPath = filepath.Join(home, ".kube", "config")
+		}
+	}
+}
+
 // KeyValuesMap converts key=value[,value] into map[string][]string.
 func KeyValuesMap(strs []string) (map[string][]string, error) {
 	res := make(map[string][]string, len(strs))
@@ -18,3 +33,14 @@ func KeyValuesMap(strs []string) (map[string][]string, error) {
 	}
 	return res, nil
 }
+
+// inCluster is to check if current process is in pod.
+func inCluster() bool {
+	f, err := os.Stat("/var/run/secrets/kubernetes.io/serviceaccount/token")
+	if err != nil || f.IsDir() {
+		return false
+	}
+
+	return os.Getenv("KUBERNETES_SERVICE_HOST") != "" &&
+		os.Getenv("KUBERNETES_SERVICE_PORT") != ""
+}

cmd/kperf/commands/virtualcluster/nodepool.go

@@ -18,6 +18,7 @@ var nodepoolCommand = cli.Command{
 		cli.StringFlag{
 			Name:  "kubeconfig",
 			Usage: "Path to the kubeconfig file",
+			Value: utils.DefaultKubeConfigPath,
 		},
 	},
 	Subcommands: []cli.Command{