inspec/docs/dsl_resource.rst

=====================================================
Resource DSL
=====================================================

InSpec provides a mechanism for defining custom resources. These become available with their respective names and provide easy functionality to profiles.

Resource location
-----------------------------------------------------

Resources may be added to profiles in the `libraries` folder:

.. code-block:: bash

  $ tree examples/profile
  examples/profile
  ...
  ├── libraries
  │   └── gordon_config.rb


Resource structure
-----------------------------------------------------

The smallest possible resource takes this form:

.. code-block:: ruby

  class Tiny < Inspec.resource(1)
    name 'tiny'
  end

Resources are written as a regular Ruby `class` which inherits from `Inspec.resource`. The number (`1`) specifies the version this resource plugin targets. As InSpec evolves, this interface may change and may require a higher version.

The following attributes can be configured:

* `name` - Identifier of the resource (required)
* `desc` - Description of the resource (optional)
* `example` - Example usage of the resource (optional)

The following methods are available to the resource:

* `inspec` - Contains a registry of all other resources to interact with the operating system or target in general.
* `skip_resource` - A resource may call this method to indicate, that requirements aren't met. All tests that use this resource will be marked as `skipped`.

The following example shows a full resource using attributes and methods to provide simple access to a configuration file:

.. code-block:: ruby

  class GordonConfig < Inspec.resource(1)
    name 'gordon_config'

    desc '
      Resource description ...
    '

    example '
      describe gordon_config do
        its("signal") { should eq "on" }
      end
    '

    # Load the configuration file on initialization
    def initialize(path = nil)
      @path = path || '/etc/gordon.conf'
      @params = SimpleConfig.new( read_content )
    end

    # Expose all parameters of the configuration file.
    def method_missing(name)
      @params[name]
    end

    private

    def read_content
      f = inspec.file(@path)
      # Test if the path exist and that it's a file
      if f.file?
        # Retrieve the file's contents
        f.content
      else
        # If the file doesn't exist, skip all tests that use gordon_config
        skip_resource "Can't read config from #{@path}."
      end
    end
  end

For a full example, see our `example resource`_.

.. _example resource: ../examples/profile