Rooster Tech Talk

Rooster

Rooster • It does the same thing everyday at the same time, whether you are sleeping or not

Rooster • Designed to run periodic tasks, on schedule

History • Previously we used the daemons gem plus the daemon generator plugin. • Headaches: • Each daemon is a separate process. • Not very DRY:

Not DRY • Each daemon has two ﬁles: • The actual code that runs as a daemon (e.g. network_point_update_daemon.rb) •

Not DRY • Each daemon has two ﬁles: • And a daemon control script (e.g. network_point_update_daemon_ctl) •

Not DRY • The only bit of code that actually does our work: AppUser.daily_amount_grant • The Rails environment is loaded within each daemon process! Not good for memory. • No centralized logging/error handling; poignantly recognized when we wanted exceptions emailed to us. • Management of each daemon process required another entry into monit's conﬁg ﬁle (eww!):

Back To The Future (of scheduled tasks)

Rooster

Rooster What does it do?

Rooster What does it do? Scratches the itches of our previous conﬁguration

Rooster It’s DRY • One daemon, monitored by monit • One Rails environment, loaded once • Easier management: TCP server (easily accessed by telnet), rake tasks, more to come... • Centralized and conﬁgurable error handling and logging: Rooster::Runner.error_handler = lambda { |e| HoptoadNotiﬁer.notify(e) }

How? • Rooster leverages 3 (optionally 4) excellent open source bits of software:

How? • Rooster leverages 3 (optionally 4) excellent open source bits of software: • EventMachine: provides event-driven I/O using the Reactor pattern. It lets you write network clients and servers without handling sockets.

How? • Rooster leverages 3 (optionally 4) excellent open source bits of software: • EventMachine: provides event-driven I/O using the Reactor pattern. It lets you write network clients and servers without handling sockets. • Rufus Scheduler: a Ruby gem for scheduling pieces of code (can leverage EventMachine if available).

How? • Rooster leverages 3 (optionally 4) excellent open source bits of software: • EventMachine: provides event-driven I/O using the Reactor pattern. It lets you write network clients and servers without handling sockets. • Rufus Scheduler: a Ruby gem for scheduling pieces of code (can leverage EventMachine if available). • daemons: A Ruby gem that provides an easy way to wrap existing ruby code to be run as a daemon, and to be controlled by simple start/stop/restart commands. (I know we moved away from our previous daemons-based solution, but not all daemons are bad).

How? • Rooster leverages 3 (optionally 4) excellent open source bits of software: • EventMachine: provides event-driven I/O using the Reactor pattern. It lets you write network clients and servers without handling sockets. • Rufus Scheduler: a Ruby gem for scheduling pieces of code (can leverage EventMachine if available). • daemons: A Ruby gem that provides an easy way to wrap existing ruby code to be run as a daemon and to be controlled by simple start/stop/restart commands. (I know we moved away from our previous daemons-based solution, but not all daemons are bad). • Chronic (Optional) - A handy gem for natural language date/ time parsing.

How? • These components ﬁt together thusly:

How? • These components ﬁt together thusly: • The rooster daemon is started, and then kicks off the Rooster::Runner.

How? • These components ﬁt together thusly: • The rooster daemon is started, and then kicks off the Rooster::Runner. • Rooster::Runner runs the main EventMachine reactor loop, loads a Rufus::Scheduler, loads (and optionally schedules) each rooster task, and starts the ControlServer.

How? • These components ﬁt together thusly: • The rooster daemon is started, and then kicks off the Rooster::Runner. • Rooster::Runner runs the main EventMachine reactor loop, loads a Rufus::Scheduler, loads (and optionally schedules) each rooster task, and starts the ControlServer. • Rooster::ControlServer is a TCP-based server that listens for Rooster control commands (e.g. schedule, unschedule, exit, etc.).

How? • These components ﬁt together thusly: • The rooster daemon is started, and then kicks off the Rooster::Runner. • Rooster::Runner runs the main EventMachine reactor loop, loads a Rufus::Scheduler, loads (and optionally schedules) each rooster task, and starts the ControlServer. • Rooster::ControlServer is a TCP-based server that listens for Rooster control commands (e.g. schedule, unschedule, exit, etc.). • Rooster::ControlClient issues commands to the ControlServer; used mainly as a rake helper.

I kan haz A EXAMPLE Pleez?

Example • I want a task that kills all kittens at 4:20pm every day • > script/generate rooster_task KittenKiller • Generates a new templated task in: RAILS_ROOT/lib/rooster/tasks/kitten_killer_task.rb • rake rooster:launch (and then maybe `rake rooster:start TASK=KittenKillerTask`)

Commands • Tag-based commands are handy for controlling only a subset of available tasks • For example, we have separate rooster tasks running on app1 and app3, and are controlled with those server-speciﬁc tags.

Future Goals • Make rooster task scheduling blocks DRYer, especially by abstracting away the ActiveRecord connection pool cleanup. • Refactor Rooster::Runner (prettier code). • Add scripts (e.g. script/rooster daemon:start) • On daemon launch, autostart tasks having a certain tag (or accept a lambda, e.g. launch_if => lamba { |task| task.tags.include?(“app1”) } )

References • http://daemons.rubyforge.org/ • http://github.com/jmettraux/rufus-scheduler/tree/master • http://rubyeventmachine.com/ • http://github.com/ﬁndchris/rooster/tree/master

The Rooster Has Spoken

But wait, there’s more!

Single Slide: Create a Rails plugin and push to github • First, go to github.com, signup, add ssh keys, and create a new project • Then...

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Rooster Tech Talk

by Chris Johnson on Dec 08, 2009

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Rooster Tech Talk — Presentation Transcript