feat: handle path list for KUBECONFIG env var

Author: ndbaker1

klient/conf/config.go

@@ -23,6 +23,7 @@ import (
 	"os"
 	"os/user"
 	"path"
+	"path/filepath"
 
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
@@ -97,7 +98,15 @@ func ResolveKubeConfigFile() string {
 	// if KUBECONFIG env is defined then use that
 	kubeConfigPath = os.Getenv(clientcmd.RecommendedConfigPathEnvVar)
 	if kubeConfigPath != "" {
-		return kubeConfigPath
+		// handle the variable as a path list, similar to client-go.
+		filePaths := filepath.SplitList(kubeConfigPath)
+		for _, filename := range filePaths {
+			if _, err := os.Stat(filename); err == nil {
+				return filename
+			}
+		}
+		// return the last path in the list if none exist yet.
+		return filePaths[len(filePaths)-1]
 	}
 
 	var (

klient/conf/config_test.go

@@ -17,6 +17,8 @@ limitations under the License.
 package conf
 
 import (
+	"fmt"
+	"os"
 	"path/filepath"
 	"testing"
 
@@ -25,15 +27,95 @@ import (
 
 var kubeconfig string
 
-func TestResolveKubeConfigFile(t *testing.T) {
-	home := homedir.HomeDir()
+func TestResolveKubeConfigFileFlag(t *testing.T) {
 	filename := ResolveKubeConfigFile()
-
-	if filename != filepath.Join(home, "test", ".kube", "config") {
+	if filename != kubeconfigpath {
 		t.Errorf("unexpected config path: %s", filename)
 	}
 }
 
+func TestResolveKubeConfigFileEnv(t *testing.T) {
+	// NOTE: not considered safe to run in parallel with other tests thats
+	// require the --kubeconfig and --kubecontext flags.
+	clearKubeconfigFlags()
+	defer setKubeconfigFlags()
+
+	kubeConfigPath1 := filepath.Join(t.TempDir(), "config")
+	if _, err := os.Create(kubeConfigPath1); err != nil {
+		t.Errorf("failed to create kubeconfig: %v", err)
+	}
+
+	kubeConfigPath2 := filepath.Join(t.TempDir(), "config")
+	if _, err := os.Create(kubeConfigPath2); err != nil {
+		t.Errorf("failed to create kubeconfig: %v", err)
+	}
+
+	t.Run("WithEnvEmpty", func(t *testing.T) {
+		t.Setenv("KUBECONFIG", "")
+
+		filename := ResolveKubeConfigFile()
+
+		// this will fallback to the true home directory.
+		if filename != filepath.Join(homedir.HomeDir(), ".kube", "config") {
+			t.Errorf("unexpected config path: %s", filename)
+		}
+	})
+
+	t.Run("WithEnvPath", func(t *testing.T) {
+		t.Setenv("KUBECONFIG", kubeConfigPath1)
+
+		filename := ResolveKubeConfigFile()
+
+		if filename != kubeConfigPath1 {
+			t.Errorf("unexpected config path: %s", filename)
+		}
+	})
+
+	t.Run("WithEnvPathListAllExist", func(t *testing.T) {
+		t.Setenv("KUBECONFIG", fmt.Sprintf("%s:%s", kubeConfigPath1, kubeConfigPath2))
+
+		filename := ResolveKubeConfigFile()
+
+		// if all exist then it will take the first.
+		if filename != kubeConfigPath1 {
+			t.Errorf("unexpected config path: %s", filename)
+		}
+	})
+
+	t.Run("WithEnvPathListFirstExists", func(t *testing.T) {
+		t.Setenv("KUBECONFIG", fmt.Sprintf("%s:fake", kubeConfigPath1))
+
+		filename := ResolveKubeConfigFile()
+
+		// if first exists then it will take the first.
+		if filename != kubeConfigPath1 {
+			t.Errorf("unexpected config path: %s", filename)
+		}
+	})
+
+	t.Run("WithEnvPathListLastExists", func(t *testing.T) {
+		t.Setenv("KUBECONFIG", fmt.Sprintf("%s:fake", kubeConfigPath1))
+
+		filename := ResolveKubeConfigFile()
+
+		// if only last exists then it will take the last.
+		if filename != kubeConfigPath1 {
+			t.Errorf("unexpected config path: %s", filename)
+		}
+	})
+
+	t.Run("WithEnvPathListNoneExist", func(t *testing.T) {
+		t.Setenv("KUBECONFIG", "fake-foo:fake-bar")
+
+		filename := ResolveKubeConfigFile()
+
+		// if none exist then it will take the last.
+		if filename != "fake-bar" {
+			t.Errorf("unexpected config path: %s", filename)
+		}
+	})
+}
+
 func TestNew(t *testing.T) {
 	cfg, err := New(ResolveKubeConfigFile())
 	if err != nil {

klient/conf/main_test.go

@@ -28,8 +28,14 @@ import (
 	"k8s.io/client-go/util/homedir"
 )
 
+var (
+	kubeconfigpath string
+	kubeContext    string
+)
+
 func TestMain(m *testing.M) {
 	setup()
+	setKubeconfigFlags()
 	code := m.Run()
 	teardown()
 	os.Exit(code)
@@ -39,8 +45,8 @@ func setup() {
 	home := homedir.HomeDir()
 
 	kubeconfigdir := filepath.Join(home, "test", ".kube")
-	kubeconfigpath := filepath.Join(kubeconfigdir, "config")
-	kubeContext := "test-context"
+	kubeconfigpath = filepath.Join(kubeconfigdir, "config")
+	kubeContext = "test-context"
 
 	// check if file exists
 	_, err := os.Stat(kubeconfigpath)
@@ -66,17 +72,33 @@ func setup() {
 
 	flag.StringVar(&kubeconfig, "kubeconfig", "", "Paths to a kubeconfig. Only required if out-of-cluster.")
 	flag.StringVar(&kubeContext, "context", "", "The name of the kubeconfig context to use. Only required if out-of-cluster.")
+}
 
+func setKubeconfigFlags() {
 	// set --kubeconfig flag
-	err = flag.Set("kubeconfig", kubeconfigpath)
-	if err != nil {
+	if err := flag.Set("kubeconfig", kubeconfigpath); err != nil {
 		log.ErrorS(err, "unexpected error while setting kubeconfig flag value")
 		return
 	}
 
 	// set --context flag
-	err = flag.Set("context", kubeContext)
-	if err != nil {
+	if err := flag.Set("context", kubeContext); err != nil {
+		log.ErrorS(err, "unexpected error while setting context flag value")
+		return
+	}
+
+	flag.Parse()
+}
+
+func clearKubeconfigFlags() {
+	// clear --kubeconfig flag
+	if err := flag.Set("kubeconfig", ""); err != nil {
+		log.ErrorS(err, "unexpected error while setting kubeconfig flag value")
+		return
+	}
+
+	// clear --context flag
+	if err := flag.Set("context", ""); err != nil {
 		log.ErrorS(err, "unexpected error while setting context flag value")
 		return
 	}