capistrano/examples/sample.rb

# You must always specify the application and repository for every recipe. The
# repository must be the URL of the repository you want this recipe to
# correspond to. The deploy_to path must be the path on each machine that will
# form the root of the application path.

set :application, "sample"
set :repository, "http://svn.example.com/#{application}/trunk"

# The deploy_to path is optional, defaulting to "/u/apps/#{application}".

set :deploy_to, "/path/to/app/root"

# The user value is optional, defaulting to user-name of the current user. This
# is the user name that will be used when logging into the deployment boxes.

set :user, "flippy"

# By default, the source control module (scm) is set to "subversion". You can
# set it to any supported scm:

set :scm, :subversion

# gateway is optional, but allows you to specify the address of a computer that
# will be used to tunnel other requests through, such as when your machines are
# all behind a VPN or something

set :gateway, "gateway.example.com"

# You can define any number of roles, each of which contains any number of
# machines. Roles might include such things as :web, or :app, or :db, defining
# what the purpose of each machine is. You can also specify options that can
# be used to single out a specific subset of boxes in a particular role, like
# :primary => true.

role :web, "www01.example.com", "www02.example.com"
role :app, "app01.example.com", "app02.example.com", "app03.example.com"
role :db,  "db01.example.com", :primary => true
role :db,  "db02.example.com", "db03.example.com"

# Define tasks that run on all (or only some) of the machines. You can specify
# a role (or set of roles) that each task should be executed on. You can also
# narrow the set of servers to a subset of a role by specifying options, which
# must match the options given for the servers to select (like :primary => true)

desc <<DESC
An imaginary backup task. (Execute the 'show_tasks' task to display all
available tasks.)
DESC

task :backup, :roles => :db, :only => { :primary => true } do
  # the on_rollback handler is only executed if this task is executed within
  # a transaction (see below), AND it or a subsequent task fails.
  on_rollback { delete "/tmp/dump.sql" }

  run "mysqldump -u theuser -p thedatabase > /tmp/dump.sql" do |ch, stream, out|
    ch.send_data "thepassword\n" if out =~ /^Enter password:/
  end
end

# Tasks may take advantage of several different helper methods to interact
# with the remote server(s). These are:
#
# * run(command, options={}, &block): execute the given command on all servers
#   associated with the current task, in parallel. The block, if given, should
#   accept three parameters: the communication channel, a symbol identifying the
#   type of stream (:err or :out), and the data. The block is invoked for all
#   output from the command, allowing you to inspect output and act
#   accordingly.
# * sudo(command, options={}, &block): same as run, but it executes the command
#   via sudo.
# * delete(path, options={}): deletes the given file or directory from all
#   associated servers. If :recursive => true is given in the options, the
#   delete uses "rm -rf" instead of "rm -f".
# * put(buffer, path, options={}): creates or overwrites a file at "path" on
#   all associated servers, populating it with the contents of "buffer". You
#   can specify :mode as an integer value, which will be used to set the mode
#   on the file.
# * render(template, options={}) or render(options={}): renders the given
#   template and returns a string. Alternatively, if the :template key is given,
#   it will be treated as the contents of the template to render. Any other keys
#   are treated as local variables, which are made available to the (ERb)
#   template.

desc "Demonstrates the various helper methods available to recipes."
task :helper_demo do
  # "setup" is a standard task which sets up the directory structure on the
  # remote servers. It is a good idea to run the "setup" task at least once
  # at the beginning of your app's lifetime (it is non-destructive).
  setup

  buffer = render("maintenance.rhtml", :deadline => ENV['UNTIL'])
  put buffer, "#{shared_path}/system/maintenance.html", :mode => 0644
  sudo "killall -USR1 dispatch.fcgi"
  run "#{release_path}/script/spin"
  delete "#{shared_path}/system/maintenance.html"
end

# You can use "transaction" to indicate that if any of the tasks within it fail,
# all should be rolled back (for each task that specifies an on_rollback
# handler).

desc "A task demonstrating the use of transactions."
task :long_deploy do
  transaction do
    update_code
    disable_web
    symlink
    migrate
  end

  restart
  enable_web
end