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Capistrano Plugin to control services with systemd
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capistrano-systemd-multiservice

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This gem adds capistrano tasks to control multiple services with systemd.

Installation

Add this line to your application's Gemfile:

gem 'capistrano-systemd-multiservice', require: false

And then execute:

$ bundle

Or install it yourself as:

$ gem install capistrano-systemd-multiservice

Usage

Add these lines to your Capfile:

require "capistrano/systemd/multiservice"
install_plugin Capistrano::Systemd::MultiService.new_service("example1")
install_plugin Capistrano::Systemd::MultiService.new_service("example2")

And put config/systemd/example1.service.erb (and config/systemd/example2.service.erb, ...) like this:

[Unit]
Description = <%= fetch(:application) %> application server example1

[Service]
Environment = RAILS_ENV=<%= fetch(:rails_env) %>
Environment = PWD=<%= current_path %>
WorkingDirectory = <%= current_path %>
ExecStart = bundle exec some-application-server start
User = exampleuser
Group = examplegroup

[Install]
WantedBy = multi-user.target
  • see systemd.service(5) for details
  • when :application is set to foo, this file will be installed as foo_example1.service (and foo_example2.service, ...)

And add these lines to config/deploy.rb if you want to reload/restart services on deploy:

after 'deploy:publishing', 'systemd:example1:restart'
after 'deploy:publishing', 'systemd:example2:reload-or-restart'

And then deploy.

# Upload and install systemd service unit files before deploy
cap STAGE systemd:example1:setup systemd:example2:setup

# Deploy as usual
cap STAGE deploy

User services

To have the service installed under your own user rather than root

require "capistrano/systemd/multiservice"
install_plugin Capistrano::Systemd::MultiService.new_service("example1", service_type: 'user')
install_plugin Capistrano::Systemd::MultiService.new_service("example2", service_type: 'user')

If using the user service type services will be installed in your users home directory under /.config/systemd/user. Systemd commands on those services can be run by passing a --user flag, e.g. systemctl --user list-unit-files Nothing else in setup should require change and Capistrano tasks should remain the same as when installing system services.

Capistrano Tasks

With install_plugin Capistrano::Systemd::MultiService.new_service("example1"), following tasks are defined.

  • systemd:example1:setup
  • systemd:example1:remove
  • systemd:example1:validate
  • systemd:example1:daemon-reload
  • systemd:example1:start
  • systemd:example1:stop
  • systemd:example1:reload
  • systemd:example1:restart
  • systemd:example1:reload-or-restart
  • systemd:example1:enable
  • systemd:example1:disable

See lib/capistrano/tasks/systemd/multiservice/system_service.rake, lib/capistrano/systemd/multiservice/system_service.rb for details.

Configuration Variables

With install_plugin Capistrano::Systemd::MultiService.new_service("example1"), following Configuration variables are defined.

  • :systemd_example1_role
  • :systemd_example1_units_src
  • :systemd_example1_units_dir
  • :systemd_example1_units_dest
  • :systemd_example1_instances
  • :systemd_example1_service
  • :systemd_example1_instance_services

See lib/capistrano/systemd/multiservice/system_service.rb for details.

Examples

Rails application with unicorn and delayed_job

Capfile

## ...snip...

require 'capistrano/systemd/multiservice'
install_plugin Capistrano::Systemd::MultiService.new_service('unicorn')
install_plugin Capistrano::Systemd::MultiService.new_service('delayed_job')

## ...snip...

config/deploy.rb

## ...snip...

set :application, 'foo'

## ...snip...

set :systemd_delayed_job_instances, ->{ 3.times.to_a }

after 'deploy:restart', 'systemd:unicorn:reload-or-restart'
after 'deploy:restart', 'systemd:delayed_job:restart'

after 'deploy:publishing', 'deploy:restart'

## ...snip...

config/systemd/unicorn.service.erb

This file will be installed as foo_unicorn.service.

[Unit]
Description = <%= fetch(:application) %> unicorn rack server

[Service]
Environment = PATH=<%= fetch(:rbenv_path) %>/shims:/usr/local/bin:/usr/bin:/bin
Environment = RBENV_VERSION=<%= fetch(:rbenv_ruby) %>
Environment = RBENV_ROOT=<%= fetch(:rbenv_path) %>
Environment = RAILS_ENV=<%= fetch(:rails_env) %>
Environment = PWD=<%= current_path %>

WorkingDirectory = <%= current_path %>

ExecStart = <%= fetch(:rbenv_path) %>/bin/rbenv exec bundle exec unicorn -c <%= current_path %>/config/unicorn.rb
ExecReload = /bin/kill -USR2 $MAINPID

PIDFile = <%= shared_path %>/tmp/pids/unicorn.pid
KillSignal = SIGQUIT
KillMode = process
TimeoutStopSec = 62
Restart = always

User = app-user
Group = app-group

[Install]
WantedBy = multi-user.target

config/systemd/delayed_job.service.erb

This file will be installed as foo_delayed_job.service.

[Unit]
Description = <%= fetch(:application) %> delayed_job
Requires = <%= fetch(:"#{prefix}_instance_services").join(" ") %>

[Service]
Type = oneshot
RemainAfterExit = yes
ExecStart  = /bin/true
ExecReload = /bin/true

[Install]
WantedBy = multi-user.target

config/systemd/delayed_job@.service.erb

This file will be installed as foo_delayed_job@.service, and creates 3 instanced service units foo_delayed_job@0.service, foo_delayed_job@1.service, foo_delayed_job@2.service because :systemd_delayed_job_instances is set to ->{ 3.times.to_a } in config/deploy.rb.

[Unit]
Description = <%= fetch(:application) %> delayed_job (instance %i)
PartOf = <%= fetch(:"#{prefix}_service") %>
ReloadPropagatedFrom = <%= fetch(:"#{prefix}_service") %>

[Service]
Type = forking

Environment = PATH=<%= fetch(:rbenv_path) %>/shims:/usr/local/bin:/usr/bin:/bin
Environment = RBENV_VERSION=<%= fetch(:rbenv_ruby) %>
Environment = RBENV_ROOT=<%= fetch(:rbenv_path) %>
Environment = RAILS_ENV=<%= fetch(:rails_env) %>
Environment = PWD=<%= current_path %>

WorkingDirectory = <%= current_path %>

ExecStart  = <%= fetch(:rbenv_path) %>/bin/rbenv exec bundle exec bin/delayed_job -p <%= fetch(:application) %> -i %i start
ExecStop   = <%= fetch(:rbenv_path) %>/bin/rbenv exec bundle exec bin/delayed_job -p <%= fetch(:application) %> -i %i stop
ExecReload = /bin/kill -HUP $MAINPID

PIDFile = <%= shared_path %>/tmp/pids/delayed_job.%i.pid
TimeoutStopSec = 22
Restart = always

User = app-user
Group = app-group

[Install]
WantedBy = multi-user.target

config/unicorn.rb

shared_path = "/path/to/shared"

worker_processes   5
listen             "#{shared_path}/tmp/sockets/unicorn.sock"
pid                "#{shared_path}/tmp/pids/unicorn.pid"
stderr_path        "#{shared_path}/log/unicorn_stderr.log"
stdout_path        "#{shared_path}/log/unicorn_stdout.log"
preload_app        true

before_exec do |server|
  ENV["BUNDLE_GEMFILE"] = "/path/to/current/Gemfile"
end

before_fork do |server, worker|
  if defined? ActiveRecord::Base
    ActiveRecord::Base.connection.disconnect!
  end

  old_pid = "#{server.config[:pid]}.oldbin"
  if old_pid != server.pid
    begin
      sig = (worker.nr + 1) >= server.worker_processes ? :QUIT : :TTOU
      Process.kill(sig, File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
    end
  end

  sleep 1
end

after_fork do |server, worker|
  if defined?(ActiveRecord::Base)
    ActiveRecord::Base.establish_connection
  end
end

Commands to setup systemd services and deploy

# Upload and install systemd service unit files before deploy
cap STAGE systemd:unicorn:setup systemd:delayed_job:setup

# Deploy as usual
cap STAGE deploy

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/groovenauts/capistrano-systemd-multiservice.

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