plugin.rb

# name: webhooks
# about: Make HTTP requests when certain events occur
# version: 0.1
# authors: Ryan Fox
# url: https://github.com/rcfox/Discourse-Webhooks

after_initialize do

  SYSTEM_GUARDIAN = Guardian.new(User.find_by(id: -1))

  # Include the SSO record with all User data for staff requests so that you
  # can figure out which of your users triggered the current webhook request.
  UserSerializer.class_eval do
    staff_attributes :single_sign_on_record
  end

  User.class_eval do
    # User.as_json seems to be broken due to no User::View being defined?
    # I don't really know what that's about. Let's just hack around it!
    def as_json(options = nil)
      user_serializer = UserSerializer.new(self, scope: SYSTEM_GUARDIAN)
      user_serializer.serializable_hash
    end
  end

  def build_event_url(url_template, event_name)
    url = String.new(url_template)
    url.gsub!("%{event_name}", event_name)
    return url
  end

  SiteSetting.webhooks_registered_events.split('|').each do |event_name|

    DiscourseEvent.on(event_name.to_sym) do |*params|

      next unless SiteSetting.webhooks_enabled

      if SiteSetting.webhooks_include_api_key
        api_key = ApiKey.find_by(user_id: nil)
        if not api_key
          Rails.logger.warn('Webhooks configured to include the "All User" API key, but it does not exist.')
        else
          params.unshift(api_key.key)
        end
      end

      uri = URI.parse(build_event_url(SiteSetting.webhooks_url_format, event_name))
      http = Net::HTTP.new(uri.host, uri.port)
      http.use_ssl = true if uri.scheme == 'https'
      http.verify_mode = OpenSSL::SSL::VERIFY_NONE unless SiteSetting.webhooks_verify_ssl

      request = Net::HTTP::Post.new(uri.path)
      request.add_field('Content-Type', 'application/json')
      request.body = params.to_json

      response = http.request(request)
      case response
      when Net::HTTPSuccess then
        # nothing
      else
        Rails.logger.error("#{uri}: #{response.code} - #{response.message}")
      end
    end

  end

end