A robust init script for running unicorn on FreeBSD
This rc script works with either RVM and RBENV installed in your deploy user's directory, or with a globally installed ruby. It correctly handle's Unicorn+Bundler idiosyncrasies.
Simply place the unicorn script in your /usr/local/etc/rc.d directory, modify it if necessary, and configure your application via variables in /etc/rc.conf
This has been tested on FreeBSD 9.0 and 9.1
The only thing you might need to configure in the rc script is to change the REQUIRE line to specify your database (I use PostreSQL so that's what's in the repo)
For example, if you were using MySQL, you would change
# REQUIRE: LOGIN postgresql
to
# REQUIRE: LOGIN mysql-server
You might need to add other services to this list if your Rails application requires them.
To get up and running quickly, adjust the REQUIRE line like above, and add edit your /etc/rc.conf:
For Capistrano or Capistrano-like directory layouts:
unicorn_enable="YES"
# this is the path to where your application is deployed via Capistrano
# (the parent directory of the `current` directory)
unicorn_directory="/u/application"
For Non-Capistrano-like layouts:
unicorn_enable="YES"
unicorn_command="/u/application/bin/unicorn_rails"
unicorn_rackup="/u/application/config.ru"
unicorn_pidfile="/u/application/tmp/pids/unicorn.pid"
unicorn_old_pidfile="/u/application/tmp/pids/unicorn.oldbin"
unicorn_listen="/u/application/tmp/sockets/unicorn.sock"
unicorn_config="/u/application/config/unicorn.rb"
unicorn_chdir="/u/application"
unicorn_user="deploy"
# Uncomment this if using a different RAILS_ENV/RACK_ENV than production
#unicorn_env="production"
You can now start Unicorn like any other FreeBSD service:
/usr/local/etc/rc.d/unicorn start
There's also a handy show command to look at your final Unicorn configuration:
/usr/local/etc/rc.d/unicorn show
You can do an old-fashioned restart, or a zero-downtime upgrade with these commands:
/usr/local/etc/rc.d/unicorn restart
/usr/local/etc/rc.d/unicorn upgrade
And when you're done riding Unicorns, you can shut it down
/usr/local/etc/rc.d/unicorn stop
The rc script does as much as possible to help you out. If you are using Capistrano, or a Capistrano-like directory structure, then you can just specify the directory of your application (the parent directory of current):
unicorn_enable="YES"
unicorn_directory="/u/application"
This infers all sorts of information about your app (you can always run /usr/local/etc/rc.d/unicorn show to see what your configuration is. Note the variable names listed here are without the leading unicorn_ prefix that you would need to specify in /etc/rc.conf):
#
# Unicorn Configuration for application
#
command: /u/application/current/bin/unicorn_rails
command_args: /u/application/current/config.ru
rackup: /u/application/current/config.ru
pidfile: /u/application/shared/tmp/pids/unicorn.pid
old_pidfile: /u/application/shared/tmp/pids/unicorn.pid.oldbin
listen:
config: /u/application/current/config/unicorn.conf.rb
init_config:
bundle_gemfile: /u/application/current/Gemfile
chdir: /u/application/current
user: deploy
nice:
env: production
flags: -E production -c /u/application/current/config/unicorn.conf.rb -D
start_command:
su -l deploy -c "export BUNDLE_GEMFILE=/u/application/current/Gemfile && cd /u/application && /u/application/current/bin/unicorn_rails -E production -c /u/application/current/config/unicorn.conf.rb -D /u/application/current/config.ru"
Let's look at these settings one by one:
command: By default, it uses the current/bin/unicorn_rails bundler binstub located in your project to ensure your gems are loaded. command comes from FreeBSD's rc.subr init system functions.
command_args: This is the standard FreeBSD's rc.subr variable that holds the arguments to the above command. The rackup setting is prepended to the beginning of this setting. Typically you don't need to set this.
rackup: This is the rackup file that unicorn uses. By default this is set to current/config.ru for capistrano projects.
pidfile: This is also part of FreeBSD's rc.subr system. This is where the built in functions will look for the pid of the process. By default, this rc script looks in the shared/tmp/pids/unicorn.pid file.
old_pidfile: This is the pidfile used by unicorn to perform zero-downtime upgrades. Procedure to replace a running unicorn executable. This rc script uses Unicorn's default convention of appending .oldbin to the end of the pidfile
listen: This is the port or socket for Unicorn to listen on. This rc script assumes that you will specify it in your project's Unicorn config file (see the next variable).
e.g.
listen "#{app}/shared/sockets/unicorn.sock", :backlog => 64
config: This is the path to Unicorn's config file where unicorn will find it's settings. By default this rc script looks for a file called current/conf/unicorn.conf.rb
init_config: This is a shell script file that is included in the environment before Unicorn is executed. In this file you can include export VAR=value statements to pass environment variables into your rails app. By default, this init script looks for a file called current/.env and uses that. If that file doesn't exist, this rc script will skip this functionality (as seen in the above example).
This could be used in conjunction with dotenv in development since dotenv accepts lines beginning with export
bundle_gemfile: This is the path to the Gemfile of your project. This rc script sets the BUNDLE_GEMFILE environment variable to this value. By default it looks to current/Gemfile. This is required so that Unicorn uses the most current Gemfile (rather than the one in the specific deployment directory) when an upgrade is performed. See Unicorn Sandboxing. This is a safeguard, you should really put this in your unicorn.conf.rb:
before_exec do |server|
ENV["BUNDLE_GEMFILE"] = "/path/to/app/current/Gemfile"
end
chdir: This is the directory we cd into before running Unicorn. By default it's the currently deployed version of your application "current/"
user: This is the user that Unicorn will be run as. By default we do like Passenger and use the owner of the unicorn_directory.
nice: The nice level to run unicorn at. Usually you'll leave this alone.
flags: This is a variable defined by FreeBSD's /etc/rc.subr init system, and contains the flags passed to the command (Unicorn in this case) when run. This variable is built up from the variables above, but you could manually specify unicorn_flags in your /etc/rc.conf to override them.
start_command: Here you can see the full command that will be run when you start this service. It's a beaut' isn't it?
You can override any of these parameter in your /etc/rc.conf by simply specifying the variables like you see below (you can pick and choose which to override).
Using your own layout is easy, you can just leave the unicorn_directory variable out of your /etc/rc.conf and specify all of the above variables manually. Here's a list of those variables for your convenience:
unicorn_command: The path to the unicorn command
unicorn_command_args: The non-flag arguments passed to the above command. This is usually the path to the Rack config.ru file, and the rackup parameter is prepended to the beginning of this setting. Typically you do not need to set this.
unicorn_rackup: This is the path to the Rack config file (typically called `config.ru`). This setting is prepended to the `command_args` parameter
unicorn_pidfile: The path where Unicorn will put its pid file
unicorn_old_pidfile: The path where Unicorn will put its `old` pid file (usually the same as the sbove with `.oldbin` appended)
unicorn_listen: The path to the socket or port to listen on. You can leave this blank to specify where to listen in the Unicorn config
unicorn_config: The path to the Unicorn config file
unicorn_chdir: The path where this script will `cd` to before starting unicorn
unicorn_user: The user to run Unicorn as
unicorn_nice: The `nice` level to run Unicorn as. Leave blank to run un-niced
unicorn_env: The RAILS_ENV (or RACK_ENV) to run your application as. (default: production)
unicorn_flags: The flags passed in to Unicorn when starting (not counting the unicorn_command_args specified above). Override this for complete control of how to start Unicorn.
This is all find and dandy, but some of you might have multiple applications running on the same server (even if it's just a staging and production version of your app).
This rc script can work with multiple applications. It works similarly to how postgresql's rc script works on FreeBSD.
You simply specify your profiles in your /etc/rc.conf with the unicorn_profiles variable. This is a space separated list of application names.
Then you can customize each application by specifying variables in this form:
unicorn_<application-name>_variable=VALUE
Here's a simple example (I can leave the _env variable out of the production declaration since it's the default value)
unicorn_enable="YES"
unicorn_profiles="application_staging application_production"
unicorn_application_staging_enable="YES"
unicorn_application_staging_directory="/u/application_staging"
unicorn_application_staging_env="staging"
unicorn_application_production_enable="YES"
unicorn_application_production_directory="/u/application_production"
You can use the simplified Capistrano directory-based configuration like above, or you can specify all of the variable's separately, for a fully custom setup
If you want to customize the default, calculated values you want to look in the _setup_directory() function. This is what is called when you specify that you want to use a Capistrano-like directory layout by specifying unicorn_directory or unicorn_<application-name>_directory in your /etc/rc.conf.
If you use a different deployment strategy than Capistrano, you could adjust the default values to work with your system.