abiosoft/colima · error

error executing template: %w

Error message

error executing template: %w

What it means

ParseTemplate (util/template.go:28) fails at t.Execute when the template parses fine but references data that the values object cannot supply — for structs this is 'can't evaluate field X in type Y', for maps a missing key, or a invoked function/method returning an error mid-render. The wrapped error identifies which field/key and template line caused it. In colima the values structs are small and fixed (e.g. {Format, InstanceId}), so this usually means template and values struct drifted apart.

Source

Thrown at util/template.go:28

// WriteTemplate writes template with body to file after applying values.
func WriteTemplate(body string, file string, values any) error {
	b, err := ParseTemplate(body, values)
	if err != nil {
		return err
	}
	return os.WriteFile(file, b, 0644)
}

// ParseTemplate parses template with body and values and returns the resulting bytes.
func ParseTemplate(body string, values any) ([]byte, error) {
	t, err := template.New("").Parse(body)
	if err != nil {
		return nil, fmt.Errorf("error parsing template: %w", err)
	}

	var b bytes.Buffer
	if err := t.Execute(&b, values); err != nil {
		return nil, fmt.Errorf("error executing template: %w", err)
	}

	return b.Bytes(), err
}

View on GitHub (pinned to c3a5f9184d)

Solutions

1. Align every {{.Field}} in the body with exported fields (exact names, case-sensitive) of the values struct
2. Guard optional values with {{if .Field}}...{{end}} instead of dereferencing blindly
3. Dry-run t.Execute(io.Discard, values) in a unit test with the real values type to catch drift
4. For map values, ensure keys exist or use {{index . "key"}} with an {{if}} existence check

Example fix

// before
values := struct{ Format bool; InstanceId string }{...}
body := "{{.Formats}}" // field name typo -> execute error

// after
body := "{{.Format}}"

// dry-run execution catches field-name drift before it matters
func templateExecutes(body string, values any) error {
    t, err := template.New("").Parse(body)
    if err != nil { return err }
    return t.Execute(io.Discard, values)
}

func isTemplateExecError(err error) bool {
    var e *template.ExecError
    return errors.As(err, &e)
}

if b, err := util.ParseTemplate(body, values); err != nil {
    if isTemplateExecError(err) {
        // template/data mismatch: report field name and template line to the user
        return fmt.Errorf("template references unknown field: %w", err)
    }
    return err
}

When it happens

Trigger: Template contains {{.Formats}} while values is struct{ Format bool; InstanceId string }; passing a map[string]any whose key set doesn't cover the template's references; a custom function used in the template returns an error.

Common situations: Renaming a struct field without updating the template literal; passing values of the wrong type into a helper that reuses ParseTemplate; templates written against an older struct shape after a colima upgrade in a fork.

Related errors

• error parsing template: %w
• error provisioning %s: %w
• error starting %s: %w
• error retrieving runtimes: %w
• error stopping %s: %w

AI-assisted analysis of abiosoft/colima@c3a5f9184d (2026-08-15). Data as JSON: /api/errors/341c83d455cd8d23. Report an issue: GitHub.