refactor: modernize Go codebase for Go 1.25

- Replace deprecated io/ioutil with os.ReadFile, os.WriteFile, etc.
- Replace interface{} with any
- Replace github.com/pkg/errors with stdlib fmt.Errorf %w wrapping
- Use errors.As() instead of direct type assertions on errors
- Use strings.Cut() for delimiter parsing
- Use slices.Contains() for linear searches
- Use t.Setenv() and t.TempDir() in tests
- Update CI workflows to Go 1.25

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/kubectx/current.go

@@ -15,11 +15,10 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
 )
 
@@ -33,7 +32,7 @@ func (_op CurrentOp) Run(stdout, _ io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	v := kc.GetCurrentContext()
@@ -41,5 +40,8 @@ func (_op CurrentOp) Run(stdout, _ io.Writer) error {
 		return errors.New("current-context is not set")
 	}
 	_, err := fmt.Fprintln(stdout, v)
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }

cmd/kubectx/delete.go

@@ -15,10 +15,10 @@
 package main
 
 import (
+	"errors"
+	"fmt"
 	"io"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
 	"github.com/ahmetb/kubectx/internal/printer"
 )
@@ -37,7 +37,7 @@ func (op DeleteOp) Run(_, stderr io.Writer) error {
 		// TODO inefficiency here. we open/write/close the same file many times.
 		deletedName, wasActiveContext, err := deleteContext(ctx)
 		if err != nil {
-			return errors.Wrapf(err, "error deleting context \"%s\"", deletedName)
+			return fmt.Errorf("error deleting context \"%s\": %w", deletedName, err)
 		}
 		if wasActiveContext {
 			printer.Warning(stderr, "You deleted the current context. Use \"%s\" to select a new context.",
@@ -55,7 +55,7 @@ func deleteContext(name string) (deleteName string, wasActiveContext bool, err e
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return deleteName, false, errors.Wrap(err, "kubeconfig error")
+		return deleteName, false, fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	cur := kc.GetCurrentContext()
@@ -73,7 +73,10 @@ func deleteContext(name string) (deleteName string, wasActiveContext bool, err e
 	}
 
 	if err := kc.DeleteContextEntry(name); err != nil {
-		return name, false, errors.Wrap(err, "failed to modify yaml doc")
+		return name, false, fmt.Errorf("failed to modify yaml doc: %w", err)
 	}
-	return name, wasActiveContext, errors.Wrap(kc.Save(), "failed to save modified kubeconfig file")
+	if err := kc.Save(); err != nil {
+		return name, wasActiveContext, fmt.Errorf("failed to save modified kubeconfig file: %w", err)
+	}
+	return name, wasActiveContext, nil
 }

cmd/kubectx/fzf.go

@@ -16,14 +16,13 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
 	"strings"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/cmdutil"
 	"github.com/ahmetb/kubectx/internal/env"
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
@@ -49,7 +48,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 			printer.Warning(stderr, "kubeconfig file not found")
 			return nil
 		}
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 	kc.Close()
 
@@ -63,7 +62,8 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
 		fmt.Sprintf("%s=1", env.EnvForceColor))
 	if err := cmd.Run(); err != nil {
-		if _, ok := err.(*exec.ExitError); !ok {
+		var exitErr *exec.ExitError
+		if !errors.As(err, &exitErr) {
 			return err
 		}
 	}
@@ -73,7 +73,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 	}
 	name, err := switchContext(choice)
 	if err != nil {
-		return errors.Wrap(err, "failed to switch context")
+		return fmt.Errorf("failed to switch context: %w", err)
 	}
 	printer.Success(stderr, "Switched to context \"%s\".", printer.SuccessColor.Sprint(name))
 	return nil
@@ -90,7 +90,7 @@ func (op InteractiveDeleteOp) Run(_, stderr io.Writer) error {
 			printer.Warning(stderr, "kubeconfig file not found")
 			return nil
 		}
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 	kc.Close()
 
@@ -108,7 +108,8 @@ func (op InteractiveDeleteOp) Run(_, stderr io.Writer) error {
 		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
 		fmt.Sprintf("%s=1", env.EnvForceColor))
 	if err := cmd.Run(); err != nil {
-		if _, ok := err.(*exec.ExitError); !ok {
+		var exitErr *exec.ExitError
+		if !errors.As(err, &exitErr) {
 			return err
 		}
 	}
@@ -120,7 +121,7 @@ func (op InteractiveDeleteOp) Run(_, stderr io.Writer) error {
 
 	name, wasActiveContext, err := deleteContext(choice)
 	if err != nil {
-		return errors.Wrap(err, "failed to delete context")
+		return fmt.Errorf("failed to delete context: %w", err)
 	}
 
 	if wasActiveContext {

cmd/kubectx/help.go

@@ -20,8 +20,6 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 // HelpOp describes printing help.
@@ -50,7 +48,10 @@ func printUsage(out io.Writer) error {
 	help = strings.ReplaceAll(help, "%SPAC%", strings.Repeat(" ", len(selfName())))
 
 	_, err := fmt.Fprintf(out, "%s\n", help)
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }
 
 // selfName guesses how the user invoked the program.

cmd/kubectx/list.go

@@ -19,7 +19,6 @@ import (
 	"io"
 
 	"facette.io/natsort"
-	"github.com/pkg/errors"
 
 	"github.com/ahmetb/kubectx/internal/cmdutil"
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
@@ -40,7 +39,7 @@ func (_ ListOp) Run(stdout, stderr io.Writer) error {
 			printer.Warning(stderr, "kubeconfig file not found")
 			return nil
 		}
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	ctxs := kc.ContextNames()

cmd/kubectx/main.go

@@ -34,7 +34,7 @@ func main() {
 
 	op := parseArgs(os.Args[1:])
 	if err := op.Run(color.Output, color.Error); err != nil {
-		printer.Error(color.Error, err.Error())
+		printer.Error(color.Error, "%s", err)
 
 		if _, ok := os.LookupEnv(env.EnvDebug); ok {
 			// print stack trace in verbose mode

cmd/kubectx/rename.go

@@ -15,11 +15,10 @@
 package main
 
 import (
+	"fmt"
 	"io"
 	"strings"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
 	"github.com/ahmetb/kubectx/internal/printer"
 )
@@ -33,12 +32,8 @@ type RenameOp struct {
 // parseRenameSyntax parses A=B form into [A,B] and returns
 // whether it is parsed correctly.
 func parseRenameSyntax(v string) (string, string, bool) {
-	s := strings.Split(v, "=")
-	if len(s) != 2 {
-		return "", "", false
-	}
-	new, old := s[0], s[1]
-	if new == "" || old == "" {
+	new, old, ok := strings.Cut(v, "=")
+	if !ok || new == "" || old == "" {
 		return "", "", false
 	}
 	return new, old, true
@@ -54,7 +49,7 @@ func (op RenameOp) Run(_, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	cur := kc.GetCurrentContext()
@@ -63,26 +58,26 @@ func (op RenameOp) Run(_, stderr io.Writer) error {
 	}
 
 	if !kc.ContextExists(op.Old) {
-		return errors.Errorf("context \"%s\" not found, can't rename it", op.Old)
+		return fmt.Errorf("context \"%s\" not found, can't rename it", op.Old)
 	}
 
 	if kc.ContextExists(op.New) {
 		printer.Warning(stderr, "context \"%s\" exists, overwriting it.", op.New)
 		if err := kc.DeleteContextEntry(op.New); err != nil {
-			return errors.Wrap(err, "failed to delete new context to overwrite it")
+			return fmt.Errorf("failed to delete new context to overwrite it: %w", err)
 		}
 	}
 
 	if err := kc.ModifyContextName(op.Old, op.New); err != nil {
-		return errors.Wrap(err, "failed to change context name")
+		return fmt.Errorf("failed to change context name: %w", err)
 	}
 	if op.Old == cur {
 		if err := kc.ModifyCurrentContext(op.New); err != nil {
-			return errors.Wrap(err, "failed to set current-context to new name")
+			return fmt.Errorf("failed to set current-context to new name: %w", err)
 		}
 	}
 	if err := kc.Save(); err != nil {
-		return errors.Wrap(err, "failed to save modified kubeconfig")
+		return fmt.Errorf("failed to save modified kubeconfig: %w", err)
 	}
 	printer.Success(stderr, "Context %s renamed to %s.",
 		printer.SuccessColor.Sprint(op.Old),

cmd/kubectx/shell.go

@@ -8,7 +8,6 @@ import (
 	"runtime"
 
 	"github.com/fatih/color"
-	"github.com/pkg/errors"
 
 	"github.com/ahmetb/kubectx/internal/env"
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
@@ -34,7 +33,7 @@ func (op ShellOp) Run(_, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 	if !kc.ContextExists(op.Target) {
 		return fmt.Errorf("no context exists with the name: \"%s\"", op.Target)
@@ -44,20 +43,20 @@ func (op ShellOp) Run(_, stderr io.Writer) error {
 	// Extract minimal kubeconfig using kubectl
 	data, err := extractMinimalKubeconfig(kubectlPath, op.Target)
 	if err != nil {
-		return errors.Wrap(err, "failed to extract kubeconfig for context")
+		return fmt.Errorf("failed to extract kubeconfig for context: %w", err)
 	}
 
 	// Write to temp file
 	tmpFile, err := os.CreateTemp("", "kubectx-shell-*.yaml")
 	if err != nil {
-		return errors.Wrap(err, "failed to create temp kubeconfig file")
+		return fmt.Errorf("failed to create temp kubeconfig file: %w", err)
 	}
 	tmpPath := tmpFile.Name()
 	defer os.Remove(tmpPath)
 
 	if _, err := tmpFile.Write(data); err != nil {
 		tmpFile.Close()
-		return errors.Wrap(err, "failed to write temp kubeconfig")
+		return fmt.Errorf("failed to write temp kubeconfig: %w", err)
 	}
 	tmpFile.Close()
 

cmd/kubectx/shell_test.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"os"
 	"runtime"
 	"testing"
 
@@ -33,13 +32,7 @@ func Test_detectShell_unix(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			orig := os.Getenv("SHELL")
-			defer os.Setenv("SHELL", orig)
-
-			os.Setenv("SHELL", tt.shellEnv)
-			if tt.shellEnv == "" {
-				os.Unsetenv("SHELL")
-			}
+			t.Setenv("SHELL", tt.shellEnv)
 
 			got := detectShell()
 			if got != tt.want {
@@ -51,9 +44,7 @@ func Test_detectShell_unix(t *testing.T) {
 
 func Test_ShellOp_blockedWhenNested(t *testing.T) {
 	// Simulate being inside an isolated shell
-	orig := os.Getenv(env.EnvIsolatedShell)
-	defer os.Setenv(env.EnvIsolatedShell, orig)
-	os.Setenv(env.EnvIsolatedShell, "1")
+	t.Setenv(env.EnvIsolatedShell, "1")
 
 	op := ShellOp{Target: "some-context"}
 	var stdout, stderr bytes.Buffer
@@ -75,10 +66,7 @@ func Test_ShellOp_blockedWhenNested(t *testing.T) {
 }
 
 func Test_resolveKubectl_envVar(t *testing.T) {
-	orig := os.Getenv("KUBECTL")
-	defer os.Setenv("KUBECTL", orig)
-
-	os.Setenv("KUBECTL", "/custom/path/kubectl")
+	t.Setenv("KUBECTL", "/custom/path/kubectl")
 	got, err := resolveKubectl()
 	if err != nil {
 		t.Fatalf("unexpected error: %v", err)
@@ -89,9 +77,7 @@ func Test_resolveKubectl_envVar(t *testing.T) {
 }
 
 func Test_resolveKubectl_inPath(t *testing.T) {
-	orig := os.Getenv("KUBECTL")
-	defer os.Setenv("KUBECTL", orig)
-	os.Unsetenv("KUBECTL")
+	t.Setenv("KUBECTL", "")
 
 	// kubectl should be findable in PATH on most dev machines
 	got, err := resolveKubectl()
@@ -104,9 +90,7 @@ func Test_resolveKubectl_inPath(t *testing.T) {
 }
 
 func Test_checkIsolatedMode_notSet(t *testing.T) {
-	orig := os.Getenv(env.EnvIsolatedShell)
-	defer os.Setenv(env.EnvIsolatedShell, orig)
-	os.Unsetenv(env.EnvIsolatedShell)
+	t.Setenv(env.EnvIsolatedShell, "")
 
 	err := checkIsolatedMode()
 	if err != nil {
@@ -115,9 +99,7 @@ func Test_checkIsolatedMode_notSet(t *testing.T) {
 }
 
 func Test_checkIsolatedMode_set(t *testing.T) {
-	orig := os.Getenv(env.EnvIsolatedShell)
-	defer os.Setenv(env.EnvIsolatedShell, orig)
-	os.Setenv(env.EnvIsolatedShell, "1")
+	t.Setenv(env.EnvIsolatedShell, "1")
 
 	err := checkIsolatedMode()
 	if err == nil {

cmd/kubectx/state.go

@@ -15,12 +15,11 @@
 package main
 
 import (
-	"io/ioutil"
+	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/cmdutil"
 )
 
@@ -35,7 +34,7 @@ func kubectxPrevCtxFile() (string, error) {
 // readLastContext returns the saved previous context
 // if the state file exists, otherwise returns "".
 func readLastContext(path string) (string, error) {
-	b, err := ioutil.ReadFile(path)
+	b, err := os.ReadFile(path)
 	if os.IsNotExist(err) {
 		return "", nil
 	}
@@ -47,7 +46,7 @@ func readLastContext(path string) (string, error) {
 func writeLastContext(path, value string) error {
 	dir := filepath.Dir(path)
 	if err := os.MkdirAll(dir, 0755); err != nil {
-		return errors.Wrap(err, "failed to create parent directories")
+		return fmt.Errorf("failed to create parent directories: %w", err)
 	}
-	return ioutil.WriteFile(path, []byte(value), 0644)
+	return os.WriteFile(path, []byte(value), 0644)
 }

cmd/kubectx/state_test.go

@@ -15,12 +15,9 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
-
-	"github.com/ahmetb/kubectx/internal/testutil"
 )
 
 func Test_readLastContext_nonExistingFile(t *testing.T) {
@@ -34,8 +31,11 @@ func Test_readLastContext_nonExistingFile(t *testing.T) {
 }
 
 func Test_readLastContext(t *testing.T) {
-	path, cleanup := testutil.TempFile(t, "foo")
-	defer cleanup()
+	dir := t.TempDir()
+	path := filepath.Join(dir, "testfile")
+	if err := os.WriteFile(path, []byte("foo"), 0644); err != nil {
+		t.Fatal(err)
+	}
 
 	s, err := readLastContext(path)
 	if err != nil {
@@ -55,10 +55,7 @@ func Test_writeLastContext_err(t *testing.T) {
 }
 
 func Test_writeLastContext(t *testing.T) {
-	dir, err := ioutil.TempDir(os.TempDir(), "state-file-test")
-	if err != nil {
-		t.Fatal(err)
-	}
+	dir := t.TempDir()
 	path := filepath.Join(dir, "foo", "bar")
 
 	if err := writeLastContext(path, "ctx1"); err != nil {
@@ -75,9 +72,7 @@ func Test_writeLastContext(t *testing.T) {
 }
 
 func Test_kubectxFilePath(t *testing.T) {
-	origHome := os.Getenv("HOME")
-	os.Setenv("HOME", filepath.FromSlash("/foo/bar"))
-	defer os.Setenv("HOME", origHome)
+	t.Setenv("HOME", filepath.FromSlash("/foo/bar"))
 
 	expected := filepath.Join(filepath.FromSlash("/foo/bar"), ".kube", "kubectx")
 	v, err := kubectxPrevCtxFile()
@@ -90,12 +85,8 @@ func Test_kubectxFilePath(t *testing.T) {
 }
 
 func Test_kubectxFilePath_error(t *testing.T) {
-	origHome := os.Getenv("HOME")
-	origUserprofile := os.Getenv("USERPROFILE")
-	os.Unsetenv("HOME")
-	os.Unsetenv("USERPROFILE")
-	defer os.Setenv("HOME", origHome)
-	defer os.Setenv("USERPROFILE", origUserprofile)
+	t.Setenv("HOME", "")
+	t.Setenv("USERPROFILE", "")
 
 	_, err := kubectxPrevCtxFile()
 	if err == nil {

cmd/kubectx/switch.go

@@ -15,10 +15,10 @@
 package main
 
 import (
+	"errors"
+	"fmt"
 	"io"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
 	"github.com/ahmetb/kubectx/internal/printer"
 )
@@ -40,39 +40,39 @@ func (op SwitchOp) Run(_, stderr io.Writer) error {
 		newCtx, err = switchContext(op.Target)
 	}
 	if err != nil {
-		return errors.Wrap(err, "failed to switch context")
+		return fmt.Errorf("failed to switch context: %w", err)
 	}
 	err = printer.Success(stderr, "Switched to context \"%s\".", printer.SuccessColor.Sprint(newCtx))
-	return errors.Wrap(err, "print error")
+	return fmt.Errorf("print error: %w", err)
 }
 
 // switchContext switches to specified context name.
 func switchContext(name string) (string, error) {
 	prevCtxFile, err := kubectxPrevCtxFile()
 	if err != nil {
-		return "", errors.Wrap(err, "failed to determine state file")
+		return "", fmt.Errorf("failed to determine state file: %w", err)
 	}
 
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return "", errors.Wrap(err, "kubeconfig error")
+		return "", fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	prev := kc.GetCurrentContext()
 	if !kc.ContextExists(name) {
-		return "", errors.Errorf("no context exists with the name: \"%s\"", name)
+		return "", fmt.Errorf("no context exists with the name: \"%s\"", name)
 	}
 	if err := kc.ModifyCurrentContext(name); err != nil {
 		return "", err
 	}
 	if err := kc.Save(); err != nil {
-		return "", errors.Wrap(err, "failed to save kubeconfig")
+		return "", fmt.Errorf("failed to save kubeconfig: %w", err)
 	}
 
 	if prev != name {
 		if err := writeLastContext(prevCtxFile, prev); err != nil {
-			return "", errors.Wrap(err, "failed to save previous context name")
+			return "", fmt.Errorf("failed to save previous context name: %w", err)
 		}
 	}
 	return name, nil
@@ -82,11 +82,11 @@ func switchContext(name string) (string, error) {
 func swapContext() (string, error) {
 	prevCtxFile, err := kubectxPrevCtxFile()
 	if err != nil {
-		return "", errors.Wrap(err, "failed to determine state file")
+		return "", fmt.Errorf("failed to determine state file: %w", err)
 	}
 	prev, err := readLastContext(prevCtxFile)
 	if err != nil {
-		return "", errors.Wrap(err, "failed to read previous context file")
+		return "", fmt.Errorf("failed to read previous context file: %w", err)
 	}
 	if prev == "" {
 		return "", errors.New("no previous context found")

cmd/kubectx/unset.go

@@ -15,10 +15,9 @@
 package main
 
 import (
+	"fmt"
 	"io"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
 	"github.com/ahmetb/kubectx/internal/printer"
 )
@@ -33,16 +32,19 @@ func (_ UnsetOp) Run(_, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	if err := kc.UnsetCurrentContext(); err != nil {
-		return errors.Wrap(err, "error while modifying current-context")
+		return fmt.Errorf("error while modifying current-context: %w", err)
 	}
 	if err := kc.Save(); err != nil {
-		return errors.Wrap(err, "failed to save kubeconfig file after modification")
+		return fmt.Errorf("failed to save kubeconfig file after modification: %w", err)
 	}
 
 	err := printer.Success(stderr, "Active context unset for kubectl.")
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }

cmd/kubectx/version.go

@@ -3,8 +3,6 @@ package main
 import (
 	"fmt"
 	"io"
-
-	"github.com/pkg/errors"
 )
 
 var (
@@ -16,5 +14,8 @@ type VersionOp struct{}
 
 func (_ VersionOp) Run(stdout, _ io.Writer) error {
 	_, err := fmt.Fprintf(stdout, "%s\n", version)
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }

cmd/kubens/current.go

@@ -15,11 +15,10 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"io"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
 )
 
@@ -29,7 +28,7 @@ func (c CurrentOp) Run(stdout, _ io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	ctx := kc.GetCurrentContext()
@@ -38,8 +37,11 @@ func (c CurrentOp) Run(stdout, _ io.Writer) error {
 	}
 	ns, err := kc.NamespaceOfContext(ctx)
 	if err != nil {
-		return errors.Wrapf(err, "failed to read namespace of \"%s\"", ctx)
+		return fmt.Errorf("failed to read namespace of \"%s\": %w", ctx, err)
 	}
 	_, err = fmt.Fprintln(stdout, ns)
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }

cmd/kubens/fzf.go

@@ -16,14 +16,13 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
 	"strings"
 
-	"github.com/pkg/errors"
-
 	"github.com/ahmetb/kubectx/internal/cmdutil"
 	"github.com/ahmetb/kubectx/internal/env"
 	"github.com/ahmetb/kubectx/internal/kubeconfig"
@@ -43,7 +42,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 			printer.Warning(stderr, "kubeconfig file not found")
 			return nil
 		}
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 	defer kc.Close()
 
@@ -57,7 +56,8 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 		fmt.Sprintf("FZF_DEFAULT_COMMAND=%s", op.SelfCmd),
 		fmt.Sprintf("%s=1", env.EnvForceColor))
 	if err := cmd.Run(); err != nil {
-		if _, ok := err.(*exec.ExitError); !ok {
+		var exitErr *exec.ExitError
+		if !errors.As(err, &exitErr) {
 			return err
 		}
 	}
@@ -67,7 +67,7 @@ func (op InteractiveSwitchOp) Run(_, stderr io.Writer) error {
 	}
 	name, err := switchNamespace(kc, choice, false)
 	if err != nil {
-		return errors.Wrap(err, "failed to switch namespace")
+		return fmt.Errorf("failed to switch namespace: %w", err)
 	}
 	printer.Success(stderr, "Active namespace is \"%s\".", printer.SuccessColor.Sprint(name))
 	return nil

cmd/kubens/help.go

@@ -20,8 +20,6 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-
-	"github.com/pkg/errors"
 )
 
 // HelpOp describes printing help.
@@ -45,7 +43,10 @@ func printUsage(out io.Writer) error {
 	help = strings.ReplaceAll(help, "%PROG%", selfName())
 
 	_, err := fmt.Fprintf(out, "%s\n", help)
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }
 
 // selfName guesses how the user invoked the program.

cmd/kubens/list.go

@@ -16,11 +16,11 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"os"
 
-	"github.com/pkg/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
@@ -36,7 +36,7 @@ func (op ListOp) Run(stdout, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	ctx := kc.GetCurrentContext()
@@ -45,12 +45,12 @@ func (op ListOp) Run(stdout, stderr io.Writer) error {
 	}
 	curNs, err := kc.NamespaceOfContext(ctx)
 	if err != nil {
-		return errors.Wrap(err, "cannot read current namespace")
+		return fmt.Errorf("cannot read current namespace: %w", err)
 	}
 
 	ns, err := queryNamespaces(kc)
 	if err != nil {
-		return errors.Wrap(err, "could not list namespaces (is the cluster accessible?)")
+		return fmt.Errorf("could not list namespaces (is the cluster accessible?): %w", err)
 	}
 
 	for _, c := range ns {
@@ -70,7 +70,7 @@ func queryNamespaces(kc *kubeconfig.Kubeconfig) ([]string, error) {
 
 	clientset, err := newKubernetesClientSet(kc)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to initialize k8s REST client")
+		return nil, fmt.Errorf("failed to initialize k8s REST client: %w", err)
 	}
 
 	var out []string
@@ -83,7 +83,7 @@ func queryNamespaces(kc *kubeconfig.Kubeconfig) ([]string, error) {
 				Continue: next,
 			})
 		if err != nil {
-			return nil, errors.Wrap(err, "failed to list namespaces from k8s API")
+			return nil, fmt.Errorf("failed to list namespaces from k8s API: %w", err)
 		}
 		next = list.Continue
 		for _, it := range list.Items {
@@ -99,11 +99,11 @@ func queryNamespaces(kc *kubeconfig.Kubeconfig) ([]string, error) {
 func newKubernetesClientSet(kc *kubeconfig.Kubeconfig) (*kubernetes.Clientset, error) {
 	b, err := kc.Bytes()
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to convert in-memory kubeconfig to yaml")
+		return nil, fmt.Errorf("failed to convert in-memory kubeconfig to yaml: %w", err)
 	}
 	cfg, err := clientcmd.RESTConfigFromKubeConfig(b)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to initialize config")
+		return nil, fmt.Errorf("failed to initialize config: %w", err)
 	}
 	return kubernetes.NewForConfig(cfg)
 }

cmd/kubens/main.go

@@ -33,7 +33,7 @@ func main() {
 	cmdutil.PrintDeprecatedEnvWarnings(color.Error, os.Environ())
 	op := parseArgs(os.Args[1:])
 	if err := op.Run(color.Output, color.Error); err != nil {
-		printer.Error(color.Error, err.Error())
+		printer.Error(color.Error, "%s", err)
 
 		if _, ok := os.LookupEnv(env.EnvDebug); ok {
 			// print stack trace in verbose mode

cmd/kubens/statefile.go

@@ -16,7 +16,6 @@ package main
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -45,7 +44,7 @@ func (f NSFile) path() string {
 
 // Load reads the previous namespace setting, or returns empty if not exists.
 func (f NSFile) Load() (string, error) {
-	b, err := ioutil.ReadFile(f.path())
+	b, err := os.ReadFile(f.path())
 	if err != nil {
 		if os.IsNotExist(err) {
 			return "", nil
@@ -61,7 +60,7 @@ func (f NSFile) Save(value string) error {
 	if err := os.MkdirAll(d, 0755); err != nil {
 		return err
 	}
-	return ioutil.WriteFile(f.path(), []byte(value), 0644)
+	return os.WriteFile(f.path(), []byte(value), 0644)
 }
 
 // isWindows determines if the process is running on windows OS.

cmd/kubens/statefile_test.go

@@ -15,8 +15,6 @@
 package main
 
 import (
-	"io/ioutil"
-	"os"
 	"runtime"
 	"strings"
 	"testing"
@@ -25,11 +23,7 @@ import (
 )
 
 func TestNSFile(t *testing.T) {
-	td, err := ioutil.TempDir(os.TempDir(), "")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.RemoveAll(td)
+	td := t.TempDir()
 
 	f := NewNSFile("foo")
 	f.dir = td

cmd/kubens/switch.go

@@ -16,10 +16,11 @@ package main
 
 import (
 	"context"
+	"errors"
+	"fmt"
 	"io"
 	"os"
 
-	"github.com/pkg/errors"
 	errors2 "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
@@ -36,7 +37,7 @@ func (s SwitchOp) Run(_, stderr io.Writer) error {
 	kc := new(kubeconfig.Kubeconfig).WithLoader(kubeconfig.DefaultLoader)
 	defer kc.Close()
 	if err := kc.Parse(); err != nil {
-		return errors.Wrap(err, "kubeconfig error")
+		return fmt.Errorf("kubeconfig error: %w", err)
 	}
 
 	toNS, err := switchNamespace(kc, s.Target, s.Force)
@@ -54,18 +55,18 @@ func switchNamespace(kc *kubeconfig.Kubeconfig, ns string, force bool) (string,
 	}
 	curNS, err := kc.NamespaceOfContext(ctx)
 	if err != nil {
-		return "", errors.Wrap(err, "failed to get current namespace")
+		return "", fmt.Errorf("failed to get current namespace: %w", err)
 	}
 
 	f := NewNSFile(ctx)
 	prev, err := f.Load()
 	if err != nil {
-		return "", errors.Wrap(err, "failed to load previous namespace from file")
+		return "", fmt.Errorf("failed to load previous namespace from file: %w", err)
 	}
 
 	if ns == "-" {
 		if prev == "" {
-			return "", errors.Errorf("No previous namespace found for current context (%s)", ctx)
+			return "", fmt.Errorf("No previous namespace found for current context (%s)", ctx)
 		}
 		ns = prev
 	}
@@ -73,22 +74,22 @@ func switchNamespace(kc *kubeconfig.Kubeconfig, ns string, force bool) (string,
 	if !force {
 		ok, err := namespaceExists(kc, ns)
 		if err != nil {
-			return "", errors.Wrap(err, "failed to query if namespace exists (is cluster accessible?)")
+			return "", fmt.Errorf("failed to query if namespace exists (is cluster accessible?): %w", err)
 		}
 		if !ok {
-			return "", errors.Errorf("no namespace exists with name \"%s\"", ns)
+			return "", fmt.Errorf("no namespace exists with name \"%s\"", ns)
 		}
 	}
 
 	if err := kc.SetNamespace(ctx, ns); err != nil {
-		return "", errors.Wrapf(err, "failed to change to namespace \"%s\"", ns)
+		return "", fmt.Errorf("failed to change to namespace \"%s\": %w", ns, err)
 	}
 	if err := kc.Save(); err != nil {
-		return "", errors.Wrap(err, "failed to save kubeconfig file")
+		return "", fmt.Errorf("failed to save kubeconfig file: %w", err)
 	}
 	if curNS != ns {
 		if err := f.Save(curNS); err != nil {
-			return "", errors.Wrap(err, "failed to save the previous namespace to file")
+			return "", fmt.Errorf("failed to save the previous namespace to file: %w", err)
 		}
 	}
 	return ns, nil
@@ -102,13 +103,15 @@ func namespaceExists(kc *kubeconfig.Kubeconfig, ns string) (bool, error) {
 
 	clientset, err := newKubernetesClientSet(kc)
 	if err != nil {
-		return false, errors.Wrap(err, "failed to initialize k8s REST client")
+		return false, fmt.Errorf("failed to initialize k8s REST client: %w", err)
 	}
 
 	namespace, err := clientset.CoreV1().Namespaces().Get(context.Background(), ns, metav1.GetOptions{})
 	if errors2.IsNotFound(err) {
 		return false, nil
 	}
-	return namespace != nil, errors.Wrapf(err, "failed to query "+
-		"namespace %q from k8s API", ns)
+	if err != nil {
+		return false, fmt.Errorf("failed to query namespace %q from k8s API: %w", ns, err)
+	}
+	return namespace != nil, nil
 }

cmd/kubens/version.go

@@ -3,8 +3,6 @@ package main
 import (
 	"fmt"
 	"io"
-
-	"github.com/pkg/errors"
 )
 
 var (
@@ -16,5 +14,8 @@ type VersionOp struct{}
 
 func (_ VersionOp) Run(stdout, _ io.Writer) error {
 	_, err := fmt.Fprintf(stdout, "%s\n", version)
-	return errors.Wrap(err, "write error")
+	if err != nil {
+		return fmt.Errorf("write error: %w", err)
+	}
+	return nil
 }