puppetlabs/puppet · error · ArgumentError

field 'data_provider' must begin with a letter

Error message

field 'data_provider' must begin with a letter

What it means

The companion branch of validate_data_provider: the value is a String but its first character is not a letter (^[^a-z] with case-insensitivity matches digits and symbols), so Puppet demands a leading letter. The rest of the string is not even examined because the format regex ^[a-zA-Z][a-zA-Z0-9_]*$ already failed at position 0.

Source

Thrown at lib/puppet/module_tool/metadata.rb:212

    def validate_version(version)
      return if SemanticPuppet::Version.valid?(version)

      err = _("version string cannot be parsed as a valid Semantic Version")
      raise ArgumentError, _("Invalid 'version' field in metadata.json: %{err}") % { err: err }
    end

    # Validates that the given _value_ is a symbolic name that starts with a letter
    # and then contains only letters, digits, or underscore. Will raise an ArgumentError
    # if that's not the case.
    #
    # @param value [Object] The value to be tested
    def validate_data_provider(value)
      if value.is_a?(String)
        unless value =~ /^[a-zA-Z][a-zA-Z0-9_]*$/
          if value =~ /^[a-zA-Z]/
            raise ArgumentError, _("field 'data_provider' contains non-alphanumeric characters")
          else
            raise ArgumentError, _("field 'data_provider' must begin with a letter")
          end
        end
      else
        raise ArgumentError, _("field 'data_provider' must be a string")
      end
    end

    # Validates that the version range can be parsed by Semantic.
    def validate_version_range(version_range)
      SemanticPuppet::VersionRange.parse(version_range)
    rescue ArgumentError => e
      raise ArgumentError, _("Invalid 'version_range' field in metadata.json: %{err}") % { err: e }
    end
  end
end

View on GitHub (pinned to e227c27540)

Solutions

1. Rename the value to start with a letter: "data_provider": "hiera4" instead of "4hiera"
2. Remove the field if data providers are not actually used
3. Prefer the canonical provider name ('hiera') unless you truly have a custom provider class

Example fix

// before - metadata.json
"data_provider": "4hiera",

// after
"data_provider": "hiera4",

value = JSON.parse(File.read('metadata.json'))['data_provider']
if value.is_a?(String)
  abort "data_provider '#{value}' must begin with a letter" unless value =~ /\A[a-zA-Z]/
end

begin
  Puppet::ModuleTool::Metadata.from_hash('data_provider' => raw)
rescue ArgumentError => e
  raise unless e.message =~ /data_provider.*begin with a letter/
  raw = "p_#{raw}"  # or rename to a proper provider identifier
  retry
end

When it happens

Trigger: A metadata.json with "data_provider": "4hiera" or "_provider" or "1" — any string starting with a digit, underscore, or symbol triggers line 212.

Common situations: Provider names that start with a number; leading-underscore 'private' naming habits carried over from other languages; placeholder values like '123' pasted from examples.

Related errors

• field 'data_provider' contains non-alphanumeric characters
• field 'data_provider' must be a string
• Dependency conflict for %{module_name}: Dependency %{name} w
• Invalid 'name' field in metadata.json: %{err}
• Invalid 'version' field in metadata.json: %{err}

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/0693c997938584e7. Report an issue: GitHub.