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129 lines
3.9 KiB
Markdown
129 lines
3.9 KiB
Markdown
---
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title: Resource DSL
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---
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# Resource DSL
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Chef InSpec provides a mechanism for defining custom resources. These become
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available with their respective names and provide easy functionality to
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profiles.
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## Resource location
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Resources may be added to profiles in the libraries folder:
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```bash
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$ tree examples/profile
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examples/profile
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...
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├── libraries
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│ └── example_config.rb
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```
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## Resource structure
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The smallest possible resource takes this form:
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```ruby
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class Tiny < Inspec.resource(1)
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name 'tiny'
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end
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```
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Resources are written as a regular Ruby class which inherits from
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Inspec.resource. The number (1) specifies the version this resource
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plugin targets. As Chef InSpec evolves, this interface may change and may
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require a higher version.
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The following attributes can be configured:
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- name - Identifier of the resource (required)
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- desc - Description of the resource (optional)
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- example - Example usage of the resource (optional)
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- supports - (Chef InSpec 2.0+) Platform restrictions of the resource (optional)
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The following methods are available to the resource:
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- inspec - Contains a registry of all other resources to interact with the operating system or target in general.
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- 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.
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The following example shows a full resource using attributes and methods
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to provide simple access to a configuration file:
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```ruby
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class ExampleConfig < Inspec.resource(1)
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name 'example_config'
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# Restrict to only run on the below platforms (if none were given, all OS's supported)
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supports platform_family: 'fedora'
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supports platform: 'centos', release: '6.9'
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# Supports `*` for wildcard matcher in the release
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supports platform: 'centos', release: '7.*'
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desc '
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Resource description ...
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'
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example '
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describe example_config do
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its("signal") { should eq "on" }
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end
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'
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# Load the configuration file on initialization
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def initialize(path = nil)
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@path = path || '/etc/example.conf'
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@params = SimpleConfig.new( read_content )
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end
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# Expose all parameters of the configuration file.
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def method_missing(name)
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@params[name]
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end
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private
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def read_content
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f = inspec.file(@path)
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# Test if the path exist and that it's a file
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if f.file?
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# Retrieve the file's contents
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f.content
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else
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# If the file doesn't exist, skip all tests that use example_config
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raise Inspec::Exceptions::ResourceSkipped, "Can't read config at #{@path}"
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end
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end
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end
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```
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For a full example, see our [example resource](https://github.com/chef/inspec/blob/master/examples/profile/libraries/example_config.rb).
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## Lazy Loading
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Prior to InSpec v4.16, resources were pre-loaded for every invocation
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of `inspec`. This was a heavy and unnecessary burden on the system and
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exacerbated startup times (especially on Windows).
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As of InSpec v4.16, resources are lazily loaded into the `inspec`
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process upon use. This greatly speeds up the initial startup costs of
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the `inspec` process and only loads what you need to use. For example, `inspec
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--version` no longer runs for 10 seconds!.
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### Overriding Core Resources
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Lazy loading does change the way the resource registry is handled in
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ways that might break some assumptions. Specifically,
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`inspec.<resource>` isn't pre-populated with the core resources that
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InSpec ships with. If you make a local/custom resource of the same
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name, referring to the core resource via `inspec.<resource>` will not
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resolve to the core resource.
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As such, overriding core resources is not recommended best practice.
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If you really do need to do this, it is easiest to make a local
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resource with a new name and refer to the core resource directly.
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Otherwise, you need to ensure that the core resource you want is
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registered (via `require "inspec/resource/<name>"`) _before_ your
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profile is run to ensure it is eagerly loaded and in the global
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resource registry.
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