Files
kubectx/cmd/kubens/switch.go
Ahmet Alp Balkan a444364ed3 fix: improve error handling and resource management in kubeconfig
This change addresses eight key improvements to the kubectx/kubens codebase:

Resource Management Fixes:
- Fix use-after-close bugs where Kubeconfig was accessed after Close()
- Fix resource leaks on error paths by ensuring defer kc.Close() is called
- Fix YAML encoder not being closed after Encode(), causing buffered data loss

API Design Improvements:
- Change ContextNames() to return ([]string, error) instead of silently returning
  nil on error, making parse failures distinguishable from empty results
- Change GetCurrentContext() to return (string, error) instead of returning ""
  for both "not set" and parse error cases
- Update all 16 call sites across cmd/kubectx and cmd/kubens packages to handle
  the new error returns while preserving backward-compatible behavior

Error Handling:
- Add explicit error handling for printer.Success() calls in 5+ locations
  by prefixing unchecked calls with _ =

Performance:
- Add slice pre-allocation in namespace list pagination using slices.Grow()
  before append loops, reducing allocations when fetching 500+ item batches

All changes maintain backward compatibility for missing kubeconfig keys while
improving error transparency and resource safety.
2026-03-08 17:42:34 -07:00

121 lines
3.3 KiB
Go

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"context"
"errors"
"fmt"
"io"
"os"
errors2 "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"github.com/ahmetb/kubectx/internal/kubeconfig"
"github.com/ahmetb/kubectx/internal/printer"
)
type SwitchOp struct {
Target string // '-' for back and forth, or NAME
Force bool // force switch even if the namespace doesn't exist
}
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 fmt.Errorf("kubeconfig error: %w", err)
}
toNS, err := switchNamespace(kc, s.Target, s.Force)
if err != nil {
return err
}
err = printer.Success(stderr, "Active namespace is \"%s\"", printer.SuccessColor.Sprint(toNS))
return err
}
func switchNamespace(kc *kubeconfig.Kubeconfig, ns string, force bool) (string, error) {
ctx, err := kc.GetCurrentContext()
if err != nil {
return "", fmt.Errorf("failed to get current context: %w", err)
}
if ctx == "" {
return "", errors.New("current-context is not set")
}
curNS, err := kc.NamespaceOfContext(ctx)
if err != nil {
return "", fmt.Errorf("failed to get current namespace: %w", err)
}
f := NewNSFile(ctx)
prev, err := f.Load()
if err != nil {
return "", fmt.Errorf("failed to load previous namespace from file: %w", err)
}
if ns == "-" {
if prev == "" {
return "", fmt.Errorf("No previous namespace found for current context (%s)", ctx)
}
ns = prev
}
if !force {
ok, err := namespaceExists(kc, ns)
if err != nil {
return "", fmt.Errorf("failed to query if namespace exists (is cluster accessible?): %w", err)
}
if !ok {
return "", fmt.Errorf("no namespace exists with name \"%s\"", ns)
}
}
if err := kc.SetNamespace(ctx, ns); err != nil {
return "", fmt.Errorf("failed to change to namespace \"%s\": %w", ns, err)
}
if err := kc.Save(); err != nil {
return "", fmt.Errorf("failed to save kubeconfig file: %w", err)
}
if curNS != ns {
if err := f.Save(curNS); err != nil {
return "", fmt.Errorf("failed to save the previous namespace to file: %w", err)
}
}
return ns, nil
}
func namespaceExists(kc *kubeconfig.Kubeconfig, ns string) (bool, error) {
// for tests
if os.Getenv("_MOCK_NAMESPACES") != "" {
return ns == "ns1" || ns == "ns2", nil
}
clientset, err := newKubernetesClientSet(kc)
if err != nil {
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
}
if err != nil {
return false, fmt.Errorf("failed to query namespace %q from k8s API: %w", ns, err)
}
return namespace != nil, nil
}