Gwooks

A DSL for quickly creating endpoints for GitHub post-receive webhooks. It makes it easy to trigger an action whenever one of your GitHub repos receives a push matching some custom conditions.

Add this line to your application's Gemfile:

gem 'gwooks'

And then execute:

$ bundle

Or install it yourself as:

$ gem install gwooks

First extend the Gwooks::Base class and use its DSL to create actions to be performed in response to a code push:

class MyActions < Gwooks::Base

  # Do something when GitHub receives a push to a repository
  # named "my_cool_project":
  repository_name "my_cool_project" do

    # You can nest matchers. The following block for example is executed
    # when GitHub receives a push to 'my_cool_project' repo's 'master' branch:
    branch "master" do
      # You have also access to the payload sent by GitHub, parsed to a hash:
      contributors = payload[:commits].map {|c| c[:author][:email] }
      contributors.uniq.each do |email|
        send_email email, "Thanks for your contribution :)"
      end
    end

    # You can match with regular exceptions too. E.g. the next block gets
    # called when GitHub receives a push with at least one commit message
    # matching the given Regexp:
    commit_message /Bump new version v(\d+\.\d+\.\d+)/ do |matches|
      matches.each do |match|
        send_email("someone@email.com", "New version released: #{match[1]}")
      end
    end

  end

  private

  def send_email(to, msg)
    # assume we define here a method to send an email
  end

end

Then provide an endpoint for the GitHub post-receive webhook making use of the class you created:

require "sinatra"

post "/webhook" do
  MyActions.call(params[:payload])
end

Alternatively, you can use the Sinatra application provided by the class Gwooks::App, which is already setup for you:

# In your config.ru
require "gwooks"

# Tell Gwooks::App to use your class
Gwooks::App.use_webhook MyActions

# Gwooks::App responds to "POST /"
run Gwooks::App

Finally set up your GitHub repo to trigger a post-receive hook pointing to your endpoint. Whenever GitHub receives a push, your endpoint will be notified, and all the matching actions will be performed.

Each of the DSL methods matches a corresponding property in the payload object (e.g. repository_owner_email matches payload["repository"]["owner"]["email"]). The payload is accessible through the payload method, parsed into a hash.

Note that all the methods starting with commits are also aliased with the singular commit, and those starting with repository are aliased with repo to improve code readability.

The signature is identical for all matcher methods:

repository_owner_email(pattern, &block)

pattern can be any object. If it is a Regexp, it is matched against the target property in the payload, otherwise it is checked for equality.

block is called once if there is at least one match, and it gets passed the match, or an array of matches if the target property is an array (all commits methods match against the array of commits and their properties). The match is a MatchData object when regexp matching is used, or the matched pattern otherwise. The block is evaluated in the instance scope, and thus can access the payload object.

Here is the full list of DSL methods:

after
before
branch
commits_added        (alias: commit_added)
commits_author_email (alias: commit_author_email)
commits_author_name  (alias: commit_author_name)
commits_id           (alias: commit_id)
commits_message      (alias: commit_message)
commits_modified     (alias: commit_modified)
commits_removed      (alias: commit_removed)
commits_timestamp    (alias: commit_timestamp)
commits_url          (alias: commit_url)
ref
repository_description (alias: repo_description)
repository_forks       (alias: repo_forks)
repository_homepage    (alias: repo_homepage)
repository_name        (alias: repo_name)
repository_owner_email (alias: repo_owner_email)
repository_owner_name  (alias: repo_owner_name)
repository_pledgie     (alias: repo_pledgie)
repository_private     (alias: repo_private)
repository_url         (alias: repo_url)
repository_watchers    (alias: repo_watchers)

Each of them matches a corresponding field in the payload sent by GitHub, except branch, which is a shortcut to match the branch using info in the ref (e.g. branch "master" is a shortcut for ref "refs/heads/master")

The payload sent by GitHub is parsed into a hash-like object and is available through the payload instance method. For convenience, a branch property is added to it, indicating the branch that received the push (extrapolated from the ref). The payload property can be indifferently accessed using symbol or string keys.

The payload object also has a resolve method that takes a string key and returns the matched property (or array of matched properties) or nil if the property or one of its parents is not set:

payload.resolve "repository.owner.name"
# returns the repo owner name, or nil if either payload["repository"],
# payload["repository"]["owner"] or payload["repository"]["owner"]["name"] are
# not set.

payload.resolve "commits.author.name"
# returns the array of each commit's author name
# Equivalent to `payload["commits"].map {|c| c["author"]["name"]}`, but it
# does not raise errors if some property is not set.

Please take into consideration that this is an alpha release, and as such the API may change frequently.

v0.0.6 - Add possibility to nest matcher methods

v0.0.5 - Add branch payload property and corresponding DSL method

v0.0.4 - Payload with indifferent access

v0.0.3 - Alias repository_ methods to repo_

v0.0.2 - Alias commits_ methods to commit_

v0.0.1 - First release