Run plugins as separate process and pass data via STDIN

.gitignore

@@ -66,4 +66,4 @@ eslint-report.html
 /locale/**/LC_MESSAGES
 /locale/**/*.time_stamp
 /.rspec
-/plugins/*
+/plugins/enabled/*

config/application.rb

@@ -28,7 +28,6 @@ module Gitlab
     config.eager_load_paths.push(*%W[#{config.root}/lib
                                      #{config.root}/app/models/hooks
                                      #{config.root}/app/models/members
-                                     #{config.root}/plugins
                                      #{config.root}/app/models/project_services
                                      #{config.root}/app/workers/concerns
                                      #{config.root}/app/services/concerns

generator_templates/plugins/template.rb

-# Requirements
-# * File name must end with _s.rb. For example, jenkins_plugin.rb.
-# * All code should be inside class. No code should be executed on file load.
-# * Class name must be same as file name.
-#   If file name is jenkins_plugin.rb then class name must be JenkinsPlugin.
-#
-# Reccomendations
-# * Code should not depend on or use GitLab classes and other code.
-# * Consider contributing your plugin to GitLab source code so we can test it
-#   and make sure it will work in further version.
-#
-class $NAMEPlugin
-  def execute(data)
-    # TODO: Implement me
-  end
-end

lib/gitlab/plugin.rb

 module Gitlab
   module Plugin
     def self.files
-      Dir.glob(Rails.root.join('plugins', '*_plugin.rb'))
+      Dir.glob(Rails.root.join('plugins/enabled/*'))
     end
 
     def self.execute_all_async(data)
       files.each do |file|
+        puts file
         PluginWorker.perform_async(file, data)
       end
     end
 
     def self.execute(file, data)
-      # TODO: Implement
-      #
-      # Reuse some code from gitlab-shell https://gitlab.com/gitlab-org/gitlab-shell/blob/master/lib/gitlab_custom_hook.rb#L40
-      # Pass data as STDIN (or JSON encode?)
-      #
-      # 1. Return true if 0 exit code
-      # 2. Return false if non-zero exit code
+      # Prepare the hook subprocess. Attach a pipe to its stdin, and merge
+      # both its stdout and stderr into our own stdout.
+      stdin_reader, stdin_writer = IO.pipe
+      hook_pid = spawn({}, file, in: stdin_reader, err: :out)
+      stdin_reader.close
+
+      # Submit changes to the hook via its stdin.
+      begin
+        IO.copy_stream(StringIO.new(data.to_json), stdin_writer)
+      rescue Errno::EPIPE
+        # It is not an error if the hook does not consume all of its input.
+      end
+
+      # Close the pipe to let the hook know there is no further input.
+      stdin_writer.close
+
+      Process.wait(hook_pid)
+      $?.success?
     end
   end
 end

lib/tasks/plugins.rake

 namespace :plugins do
-  desc 'Generate skeleton for new plugin'
-  task generate: :environment do
-    ARGV.each { |a| task a.to_sym { } }
-    name = ARGV[1]
-
-    unless name.present?
-      puts 'Error. You need to specify a name for the plugin'
-      exit 1
-    end
-
-    class_name = name.classify
-    param = name.underscore
-    file_path = Rails.root.join('plugins', param + '_plugin.rb')
-    template = File.read(Rails.root.join('generator_templates', 'plugins', 'template.rb'))
-    template.gsub!('$NAME', class_name)
-
-    if File.write(file_path, template)
-      puts "Done. Your plugin saved under #{file_path}."
-      puts 'Feel free to edit it.'
-    else
-      puts "Failed to save #{file_path}."
-    end
-  end
-
   desc 'Validate existing plugins'
   task validate: :environment do
     puts 'Validating plugins from /plugins directory'

plugins/available/save_to_file.clj

+#!/usr/bin/env clojure
+(let [in (slurp *in*)]
+  (spit "/tmp/clj-data.txt" in))

plugins/available/save_to_file.rb

+#!/usr/bin/env ruby
+x = STDIN.read
+File.write('/tmp/rb-data.txt', x)