• Ruby >= 1.9 (JRuby and C-Ruby/YARV are supported)

Need help with getting Capistrano up and running? Got a code problem you want to get solved quickly?

Get Capistrano support on CodersClan.

Add this line to your application's Gemfile:

gem 'capistrano', '~> 3.2.0'

And then execute:

$ bundle install

Capify: make sure there's no "Capfile" or "capfile" present

$ bundle exec cap install

This creates the following files:

├── Capfile
├── config
│   ├── deploy
│   │   ├── production.rb
│   │   └── staging.rb
│   └── deploy.rb
└── lib
    └── capistrano
            └── tasks

To create different stages:

$ bundle exec cap install STAGES=local,sandbox,qa,production

$ bundle exec cap -T

$ bundle exec cap staging deploy
$ bundle exec cap production deploy

$ bundle exec cap production deploy --dry-run
$ bundle exec cap production deploy --prereqs
$ bundle exec cap production deploy --trace

server 'example.com', roles: [:web, :app]
server 'example.org', roles: [:db, :workers]
desc "Report Uptimes"
task :uptime do
  on roles(:all) do |host|
    execute :any_command, "with args", :here, "and here"
    info "Host #{host} (#{host.roles.to_a.join(', ')}):\t#{capture(:uptime)}"
  end
end

Note:

tl;dr: execute(:bundle, :install) and execute('bundle install') don't behave identically!

execute() has a subtle behaviour. When calling within './directory' { execute(:bundle, :install) } for example, the first argument to execute() is a Stringish with no whitespace. This allows the command to pass through the SSHKit::CommandMap which enables a number of powerful features.

When the first argument to execute() contains whitespace, for example within './directory' { execute('bundle install') } (or when using a heredoc), neither Capistrano, nor SSHKit can reliably predict how it should be shell escaped, and thus cannot perform any context, or command mapping, that means that the within(){} (as well as with(), as(), etc) have no effect. There have been a few attempts to resolve this, but we don't consider it a bug although we acknowledge that it might be a little counter intuitive.

Where calling on the same task name, executed in order of inclusion

# call an existing task
before :starting, :ensure_user

after :finishing, :notify


# or define in block
before :starting, :ensure_user do
  #
end

after :finishing, :notify do
  #
end

If it makes sense for your use case (often, that means generating a file) the Rake prerequisite mechanism can be used:

desc "Create Important File"
file 'important.txt' do |t|
  sh "touch #{t.name}"
end
desc "Upload Important File"
task :upload => 'important.txt' do |t|
  on roles(:all) do
    upload!(t.prerequisites.first, '/tmp')
  end
end

The final way to call out to other tasks is to simply invoke() them:

namespace :example do
  task :one do
    on roles(:all) { info "One" }
  end
  task :two do
    invoke "example:one"
    on roles(:all) { info "Two" }
  end
end

This method is widely used.

desc "Ask about breakfast"
task :breakfast do
  ask(:breakfast, "pancakes")
  on roles(:all) do |h|
    execute "echo \"$(whoami) wants #{fetch(:breakfast)} for breakfast!\""
  end
end

Perfect, who needs telephones.

When using ask to get user input, you can pass echo: false to prevent the input from being displayed:

ask(:database_password, "default", echo: false)

Password authentication can be done via set and ask in your deploy environment file (e.g.: config/deploy/production.rb)

set :password, ask('Server password', nil)
server 'server.domain.com', user: 'ssh_user_name', port: 22, password: fetch(:password), roles: %w{web app db}

Local tasks can be run by replacing on with run_locally

desc 'Notify service of deployment'
task :notify do
  run_locally do
    with rails_env: :development do
      rake 'service:notify'
    end
  end
end

Of course, you can always just use standard ruby syntax to run things locally

desc 'Notify service of deployment'
task :notify do
  %x('RAILS_ENV=development bundle exec rake "service:notify"')
end

Alternatively you could use the rake syntax

desc "Notify service of deployment"
task :notify do
   sh 'RAILS_ENV=development bundle exec rake "service:notify"'
end

Note: Here be dragons. The console is very immature, but it's much more cleanly architected than previous incarnations and it'll only get better from here on in.

Execute arbitrary remote commands, to use this simply add require 'capistrano/console' which will add the necessary tasks to your environment:

$ bundle exec cap staging console

Then, after setting up the server connections, this is how that might look:

$ bundle exec cap production console
capistrano console - enter command to execute on production
production> uptime
 INFO [94db8027] Running /usr/bin/env uptime on [email protected]:22
DEBUG [94db8027] Command: /usr/bin/env uptime
DEBUG [94db8027]   17:11:17 up 50 days, 22:31,  1 user,  load average: 0.02, 0.02, 0.05
 INFO [94db8027] Finished in 0.435 seconds command successful.
production> who
 INFO [9ce34809] Running /usr/bin/env who on [email protected]:22
DEBUG [9ce34809] Command: /usr/bin/env who
DEBUG [9ce34809]  leehambley pts/0        2013-06-13 17:11 (port-11262.pppoe.wtnet.de)
 INFO [9ce34809] Finished in 0.420 seconds command successful.

There is a configuration option which asks the backend driver to ask the remote host to assign the connection a pty. A pty is a pseudo-terminal, which in effect means tell the backend that this is an interactive session. This is normally a bad idea.

Most of the differences are best explained by this page from the author of rbenv.

When Capistrano makes a connection it is a non-login, non-interactive shell. This was not an accident!

It's often used as a band aid to cure issues related to RVM and rbenv not loading login and shell initialisation scripts. In these scenarios RVM and rbenv are the tools at fault, or at least they are being used incorrectly.

Whilst, especially in the case of language runtimes (Ruby, Node, Python and friends in particular) there is a temptation to run multiple versions in parallel on a single server and to switch between them using environmental variables, this is an anti-pattern, and symptomatic of bad design (e.g. you're testing a second version of Ruby in production because your company lacks the infrastructure to test this in a staging environment).

The following variables are settable:

Support removed for following variables:

SSHKit is the driver for SSH connections behind the scenes in Capistrano. Depending on how deep you dig, you might run into interfaces that come directly from SSHKit (the configuration is a good example).

Capistrano has two test suites: an RSpec suite and a Cucumber suite. The RSpec suite handles quick feedback unit specs. The Cucumber features are an integration suite that uses Vagrant to deploy to a real virtual server. In order to run the Cucumber suite you will need to install Vagrant and Vagrant supported virtualization software like VirtualBox.

# To run the RSpec suite
$ rake spec

# To run the Cucumber suite
$ rake features

# To run the Cucumber suite and leave the VM running (faster for subsequent runs)
$ rake features KEEP_RUNNING=1

MIT License (MIT)

Copyright (c) 2012-2013 Tom Clements, Lee Hambley

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.