Archfiend

Archfiend (/ˈɑrtʃˈfind/) - a basic daemon generator. It features boilerplate for common development tools (ActiveRecord, RSpec, FactoryBot, RuboCop), handles daemonizing, configuration, logging and more. It provides a way to structure backend applications in an organized manner.

Contents

• Getting started
• Primitives
• Featured gems
• Changelog
• Roadmap
• Contributing
• License
• Code of Conduct

Getting started

Archfiend provides the archfiend executable, which features a daemon generator.

  $ bundle exec archfiend new my_new_daemon # Creates the new daemon
  $ cd my_new_daemon
  $ cp config/database.yml{.example,}       # Currently, it ships with ActiveRecord, database configuration is required
  $ bin/start                               # Start without daemonization
  2018-10-09T13:59:55.874Z 88087 TID-ovtqe0m53 INFO: Starting up
  2018-10-09T13:59:56.301Z 88087 TID-ovtqu0g3f INFO: Starting thread BarThreadLoop
  2018-10-09T13:59:56.303Z 88431 TID-ovtqe0m53 INFO: Starting subprocess FooSubprocessLoop

Primitives

Daemons generated with Archfiend are structured around ThreadLoops and SubprocessLoops. They provide entry points for any user code. There is no limit on the number of each, you should use your judgement on how many your target environment can realistically handle.

ThreadLoops

When started, Archfiend instantiates each ThreadLoop subclass in a separate thread and calls its #run method. By default, #run wraps looped execution of #iterate with StandardError handling. You are supposed to either provide the #iterate method or shadow the #run method to fully take over the control of the thread. Bear in mind that any unhandled exception will terminate the whole process. If your code deals with exceptions that are not subclasses of StandardError, make sure you handle it on your own.

With MRI, parallel threads execution happens only when one of threads waits for IO. This should be fairly often in network communicating daemons.

SubprocessLoops

When started, archfiend instantiates each SubprocessLoop subclass in a separate fork and calls its #run method. By default, #run wraps looped execution of #iterate with StandardError handling. You are supposed to either provide the #iterate method or shadow the #run method to fully take over the control of the process. Subprocesses are killed when the main daemon process exits. If a subprocess gets terminated, it does not kill the main process. The main process doesn't restart its subprocesses by default.

Featured gems

ActiveRecord

ActiveRecord is available and configured using the config/database.yml, you can create regular AR model files inside app/models. When creating multi-threaded daemons, make sure connection pool is handled correctly (that connections are released to the pool after a thread finishes) and that the pool has enough open connections (default is 5).

Migrations are provided by the ActiveRecord::Migrations gem, you can use following rake tasks

rake db:migrate                       # Migrate the database (options: VERSION=x, VERBOSE=false, SCOPE=blog)
rake db:rollback                      # Rolls the schema back to the previous version (specify steps w/ STEP=n)
rake db:migrations:new[name,options]  # Creates a new migration file with the specified name

Please see bundle exec rake -T for more options.

Clockwork

Archfiend provides the Clockwork integration, so daemons can schedule recurring tasks. Uncomment the contents of the clockwork/clockwork.rb file to enable it. If the daemon doesn't use clockwork, feel free to remove the file, the directory and the Gemfile entry.

Settings

The config gem is used to handle multi-environment settings.

rbtrace

For debugging, daemons generated with Archfiend include rbtrace. By default, it is enabled in the development environment.

RSpec / RuboCop

Newly generated daemons come with integrations for RSpec and RuboCop.

Changelog

See CHANGES.md for the list of changes.

Roadmap

See ROADMAP.md for the uncommitted list of ideas for future.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/toptal/archfiend. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Archfiend project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.