ahmetb/kubectx · error

file lookup

Error message

file %d lookup: %w

What it means

contextNodeWithFileIndex wraps an error from contexts.Pipe(yaml.Lookup("[name=" + name + "]")) as "file %d lookup: %w". The YAML field lookup for the context name fails structurally in file i — not 'not found', but an error evaluating the lookup expression over the contexts node.

Solutions

1. Open the kubeconfig file at the reported index and inspect each entry under 'contexts' for a proper 'name' field.
2. Fix or remove malformed context entries so each is a mapping with name/cluster/user.
3. Validate with kubectl config view --kubeconfig <file> until it parses cleanly.
4. Re-merge multi-file KUBECONFIG inputs with a tool that produces valid entries.

Example fix

// before (invalid entry breaks lookup)
contexts:
  - just-a-string
// after
contexts:
  - name: my-ctx
    context:
      cluster: my-cluster
      user: my-user

// Go: verify context entries are well-formed maps before lookup operations
type contextEntry struct {
	Name    string `yaml:"name"`
	Context struct {
		Cluster string `yaml:"cluster"`
		User    string `yaml:"user"`
	} `yaml:"context"`
}
// each item in 'contexts' must unmarshal into this shape before Pipe(Lookup) can succeed

if err := kc.ModifyContextName(old, new); err != nil {
	if strings.Contains(err.Error(), "lookup") {
		fmt.Fprintln(os.Stderr, "A contexts entry is malformed; ensure every context is a mapping with a 'name' field.")
	}
	return err
}

When it happens

Trigger: During contextNodeWithFileIndex iteration over k.files, Pipe(yaml.Lookup(...)) returns an error for file i, usually when the contexts node items are not the expected mapping shape (e.g. a context entry is not a map, or the list contains scalars), making the name-field lookup invalid.

Common situations: A contexts list containing malformed entries (missing name field, wrong types) after manual editing or a bad merge; a file where 'contexts' is a map instead of a list.

Related errors

• failed to close encoder for file
• failed to parse kubeconfig
• file
• kubeconfig error
• kubeconfig error

AI-assisted analysis of ahmetb/kubectx@12ad6fb22e (2026-09-02). Data as JSON: /api/errors/d739062662724d89. Report an issue: GitHub.

Appendix: source

Thrown at internal/kubeconfig/contexts.go:52

	}
	return contexts, nil
}

// contextNodeWithFileIndex searches for a context by name across all files.
// Returns the context node and the index of the file that contains it.
// Files without a valid "contexts" sequence are skipped, but if errors occur
// during lookup they are included in the final error message.
func (k *Kubeconfig) contextNodeWithFileIndex(name string) (*yaml.RNode, int, error) {
	var fileErrors []error
	for i := range k.files {
		contexts, err := contextsNodeOf(&k.files[i])
		if err != nil {
			fileErrors = append(fileErrors, fmt.Errorf("file %d: %w", i, err))
			continue
		}
		context, err := contexts.Pipe(yaml.Lookup("[name=" + name + "]"))
		if err != nil {
			fileErrors = append(fileErrors, fmt.Errorf("file %d lookup: %w", i, err))
			continue
		}
		if context != nil {
			return context, i, nil
		}
	}
	if len(fileErrors) > 0 {
		return nil, -1, fmt.Errorf("context with name %q not found (errors in files: %w)",
			name, errors.Join(fileErrors...))
	}
	return nil, -1, fmt.Errorf("context with name %q not found", name)
}

func (k *Kubeconfig) contextNode(name string) (*yaml.RNode, error) {
	node, _, err := k.contextNodeWithFileIndex(name)
	return node, err
}

View on GitHub (pinned to 12ad6fb22e)