hashicorp/nomad · error

format flag required

Error message

format flag required

What it means

VarPutCommand.makeVariable requires the -format flag (hcl or json) to know how to parse the variable contents. When no format was supplied (empty string), it returns this error before parsing anything.

Source

Thrown at command/var_put.go:431

		out.Path = path
		out.Namespace = c.Meta.namespace
		out.Items = make(map[string]string)
		return out, nil
	}

	switch c.inFmt {
	case "json":
		err = json.Unmarshal(c.contents, out)
		if err != nil {
			return nil, fmt.Errorf("error unmarshaling json: %w", err)
		}
	case "hcl":
		out, err = parseVariableSpec(c.contents, c.verbose)
		if err != nil {
			return nil, fmt.Errorf("error parsing hcl: %w", err)
		}
	case "":
		return nil, errors.New("format flag required")
	default:
		return nil, fmt.Errorf("unknown format flag value")
	}

	// It is possible a specification file was used which did not declare any
	// items. Therefore, default the entry to avoid panics and ensure this type
	// of use is valid.
	if out.Items == nil {
		out.Items = make(map[string]string)
	}

	// Handle cases where values are provided by CLI flags that modify the
	// the created variable. Typical of a "copy" operation, it is a convenience
	// to reset the Create and Modify metadata to zero.
	var resetIndex bool

	// Step on the namespace in the object if one is provided by flag
	if c.Meta.namespace != "" && c.Meta.namespace != out.Namespace {

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Add -in=hcl or -in=json (matching your input contents) to the command
2. If using a spec file, ensure the format flag is still provided
3. Check the command help for the exact flag name in your version

Example fix

// before
vault kv put secret/foo @spec.hcl
// after
vault kv put -in=hcl secret/foo @spec.hcl

if inFmt == "" {
	return errors.New("-in (hcl|json) is required when supplying contents to kv put")
}
if inFmt != "hcl" && inFmt != "json" {
	return fmt.Errorf("invalid -in %q", inFmt)
}

_, err := cmd.makeVariable()
if err != nil {
	if err.Error() == "format flag required" {
		// re-invoke with -in=hcl or -in=json
	}
	return err
}

When it happens

Trigger: Running `vault kv put` (var put) with data/contents but without -in/-format, so c.format (inFmt) is "" when makeVariable switches on it.

Common situations: Piping a file via stdin without specifying -in=hcl or -in=json; upgrading from a workflow where format defaulted implicitly; scripts missing the flag after refactor.

Understand the failure class

Background: "--flag is required" and "must specify" CLI errors: how missing-required-flag validation works and how to fix it — this error's family across 20 libraries.

Related errors

• The '-template' flag is only valid when using 'go-template'
• A template must be supplied using '-template' when using go-
• Invalid value for "-out"; valid values are [go-template, hcl
• The '-template' flag is only valid when using 'go-template'
• A template must be supplied using '-template' when using go-

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/95df70045b8f6174. Report an issue: GitHub.