do not fail on non-existing kubeconfig files

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

cmd/kubectx/fzf.go

@@ -13,6 +13,7 @@ import (
 	"github.com/mattn/go-isatty"
 
 	"github.com/ahmetb/kubectx/internal/env"
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
 	"github.com/ahmetb/kubectx/internal/printer"
 )
 
@@ -21,6 +22,17 @@ type InteractiveSwitchOp struct {
 }
 
 func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
+	// parse kubeconfig just to see if it can be loaded
+	kc := new(kubeconfig.Kubeconfig).WithLoader(defaultLoader)
+	if err := kc.Parse(); err != nil {
+		if isENOENT(err) {
+			printer.Warning(stderr, "kubeconfig file not found")
+			return nil
+		}
+		return errors.Wrap(err, "kubeconfig error")
+	}
+	kc.Close()
+
 	cmd := exec.Command("fzf", "--ansi", "--no-preview")
 	var out bytes.Buffer
 	cmd.Stdin = os.Stdin

cmd/kubectx/kubeconfig.go

@@ -33,7 +33,7 @@ func (*StandardKubeconfigLoader) Load() (kubeconfig.ReadWriteResetCloser, error)
 	f, err := os.OpenFile(cfgPath, os.O_RDWR, 0)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return nil, errors.Errorf("kubeconfig file not found at %s", cfgPath)
+			return nil, errors.Wrap(err, "kubeconfig file not found")
 		}
 		return nil, errors.Wrap(err, "failed to open file")
 	}

cmd/kubectx/kubeconfig_test.go

@@ -6,8 +6,9 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
-)
 
+	"github.com/ahmetb/kubectx/internal/kubeconfig"
+)
 
 func withTestVar(key, value string) func() {
 	// TODO(ahmetb) this method is currently duplicated
@@ -131,6 +132,18 @@ func Test_kubeconfigPath_envOvverideDoesNotSupportPathSeparator(t *testing.T) {
 	}
 }
 
+func TestStandardKubeconfigLoader_returnsNotFoundErr(t *testing.T) {
+	defer withTestVar("KUBECONFIG", "foo")()
+	kc := new(kubeconfig.Kubeconfig).WithLoader(defaultLoader)
+	err := kc.Parse()
+	if err == nil {
+		t.Fatal("expected err")
+	}
+	if !isENOENT(err) {
+		t.Fatalf("expected ENOENT error; got=%v", err)
+	}
+}
+
 func testfile(t *testing.T, contents string) (path string, cleanup func()) {
 	t.Helper()
 

cmd/kubectx/list.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"io"
+	"os"
 
 	"facette.io/natsort"
 	"github.com/fatih/color"
@@ -15,10 +16,14 @@ import (
 // ListOp describes listing contexts.
 type ListOp struct{}
 
-func (_ ListOp) Run(stdout, _ io.Writer) error {
+func (_ ListOp) Run(stdout, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(defaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
+		if isENOENT(err) {
+			printer.Warning(stderr, "kubeconfig file not found")
+			return nil
+		}
 		return errors.Wrap(err, "kubeconfig error")
 	}
 
@@ -45,3 +50,14 @@ func (_ ListOp) Run(stdout, _ io.Writer) error {
 	}
 	return nil
 }
+
+// isENOENT determines if the underlying error is os.IsNotExist. Right now
+// errors from github.com/pkg/errors doesn't work with os.IsNotExist.
+func isENOENT(err error) bool {
+	for e := err; e != nil; e = errors.Unwrap(e) {
+		if os.IsNotExist(e) {
+			return true
+		}
+	}
+	return false
+}