unicorn_relay¶ ↑

Description¶ ↑

The executable unicorn_relay contained in this gem allows you to supervise unicorn via runit by relaying signals to it while keep running under supervision and also handles the necessary work for handling pids, pid files, etc.

Usage¶ ↑

You can start unicorn_relay in your runit run script like this:

#!/bin/sh

# your ruby GC configuration variables: export UNICORN_GC=…
export PID_FILE="/some/where/pids/unicorn.pid"

cd "/some/where"
exec 2>&1
exec chpst -u my_user bundle exec unicorn_relay unicorn -c config/unicorn_config.rb

In your unicorn_config.rb configuration file you have to handle tearing down an eventual old unicorn master when a new worker starts by calling UnicornRelay::Teardown#perform as shown here:

before_fork do |server, worker|
  UnicornRelay::Teardown.new(
    pid_file: '/some/where/pids/unicorn.pid.oldbin',
    server:   server
  ).perform
end

The following signals will just be relayed to the forked unicorn processes:

HUP
USR1
USR2
TTIN
TTOU
WINCH

These signals will shutdown the supervised unicorn process:

QUIT
TERM
INT

In order to shutdown unicorn unicorn_relay just relays the INT and QUIT signals, but changes the TERM signal to QUIT and then waits for the forked processes to finish.

Now you can stop unicorn gracefully with the command

sv stop SERVICE

or w/o grace by executing:

sv interrupt SERVICE

If you run

sv 2 SERVICE

a new unicorn master is forked that is still controlled by the currently running and supervised unicorn_relay script. The latter enables you to load new code into your running app with a rolling restart behaviour, that is without interruptions of service.

Author¶ ↑

Florian Frank

License¶ ↑

This software is licensed under the Apache 2.0 license.