CloudInit Userdata

A Ruby client for parsing and validating CloudInit userdata.

This repository is Experimental meaning that it's based on untested ideas or techniques and not yet established or finalized or involves a radically new and innovative style! This means that support is best effort (at best!) and we strongly encourage you to NOT use this in production.

Usage

require 'cloudinit_userdata'

userdata = CloudInit::Userdata.parse <<-USERDATA.strip
  #!/bin/bash

  echo "Hello world!"
USERDATA

userdata.class # CloudInit::Userdata::ShellScript
userdata.valid? # true

Currently understands all of the core CloudInit formats. Mime Multipart and gzipped userdata are also supported.

An adapter is also included for JSON userdata (used by CoreOS/ignition), but it is not loaded by default, since it is not part of the original implementation. To include it, do the following somewhere:

require 'cloudinit_userdata/formats/json'
CloudInit::Userdata.register_format(CloudInit::Userdata::JSON)

Custom Adapters

You can implement formatters for your custom types of userdata. Formatters should inherit from CloudInit::Userdata, and are expected to implement the .match? method at minimum.

Formatters may also implement #validate, which will be called automatically by CloudInit::Userdata#valid?.

Formatters may also implement .mimetypes and return an array of mimetype strings that will be recognized for Mime Multipart userdata.

Finally, custom formatters must be registered with this library using the CloudInit::Userdata.register_format(<your format class>).

Known Limitations

This library does not validate the semantics of userdata, since the only way to do that accurately is to actually run the userdata on a machine, and we obviously can't do that. Rather, this library attempts to provide some basic intelligence and parse-checking around userdata formats.

Contributing

Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
Fork the project.
Start a feature/bugfix branch.
Commit and push until you are happy with your contribution.
Make sure to add tests for it. This is important so we don't break it in a future version unintentionally. You can run the test suite with bundle exec rake.
Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so we can cherry-pick around it.