Deploys your project. This calls both `update' and `restart'. Note that this will generally only work for applications that have already been deployed once. For a “cold” deploy, you'll want to take a look at the `deploy:cold' task, which handles the cold start specifically.

task :default do
  update
  restart
end

Deploys and starts a `cold' application. This is useful if you have not deployed your application before, or if your application is (for some other reason) not currently running. It will deploy the code, run any pending migrations, and then instead of invoking `deploy:restart', it will invoke `deploy:start' to fire up the application servers.

task :cold do
  update
  migrate
  start
end

Copies your project and updates the symlink. It does this in a transaction, so that if either `update_code' or `symlink' fail, all changes made to the remote servers will be rolled back, leaving your system in the same state it was in before `update' was invoked. Usually, you will want to call `deploy' instead of `update', but `update' can be handy if you want to deploy, but not immediately restart your application.

task :update do
  transaction do
    update_code
    symlink
  end
end

Copies your project to the remote servers. This is the first stage of any deployment; moving your updated code and assets to the deployment servers. You will rarely call this task directly, however; instead, you should call the `deploy' task (to do a complete deploy) or the `update' task (if you want to perform the `restart' task separately).

You will need to make sure you set the :scm variable to the source control software you are using (it defaults to :subversion), and the :deploy_via variable to the strategy you want to use to deploy (it defaults to :checkout).

task :update_code, :except => { :no_release => true } do
  on_rollback { run "rm -rf #{release_path}; true" }
  strategy.deploy!
  finalize_update
end

Run the migrate rake task. By default, it runs this in most recently deployed version of the app. However, you can specify a different release via the migrate_target variable, which must be one of :latest (for the default behavior), or :current (for the release indicated by the `current' symlink). Strings will work for those values instead of symbols, too. You can also specify additional environment variables to pass to rake via the migrate_env variable. Finally, you can specify the full path to the rake executable by setting the rake variable. The defaults are:

set :rake,           "rake"
set :rails_env,      "production"
set :migrate_env,    ""
set :migrate_target, :latest

task :migrate, :roles => :db, :only => { :primary => true } do
  rake = fetch(:rake, "rake")
  rails_env = fetch(:rails_env, "production")
  migrate_env = fetch(:migrate_env, "")
  migrate_target = fetch(:migrate_target, :latest)

  directory = case migrate_target.to_sym
    when :current then current_path
    when :latest  then latest_release
    else raise ArgumentError, "unknown migration target #{migrate_target.inspect}"
    end
  run "cd #{directory}; #{rake} RAILS_ENV=#{rails_env} #{migrate_env} db:migrate"
end

Below are some possible errors that you could encounter while running cap tasks

connection failed for: prdweb1.exphosted.com (Errno::ETIMEDOUT: Connection timed out - connect(2)) 

You will get Password prompt:

Password:

connection failed for: prdweb1.exphosted.com (Net::SSH::AuthenticationFailed: expprdw1)

*** [err :: prdweb1.exphosted.com] mkdir: cannot create directory `/deploy': Permission denied (or)
*** [err :: prdweb1.exphosted.com] mkdir: cannot create directory `/deploy/crossbow': Permission denied
failed: "sh -c 'mkdir -p /deploy/crossbow /deploy/crossbow/releases /deploy/crossbow/shared /deploy/crossbow/shared/system /deploy/crossbow/shared/log /deploy/crossbow/shared/pids &&  chmod g+w /deploy/crossbow /deploy/crossbow/releases /deploy/crossbow/shared /deploy/crossbow/shared/system /deploy/crossbow/shared/log /deploy/crossbow/shared/pids'" on prdweb1.exphosted.com

*** [err :: prdweb1.exphosted.com] ln: creating symbolic link `/deploy/crossbow/releases/20110525203341/config/database.yml' to `/deploy/crossbow/database.yml': No such file or directory

 * executing `deploy:migrate'
 * executing "cd /deploy/crossbow/releases/20110525213821; bundle exec rake RAILS_ENV=production  db:migrate"
  servers: ["prdweb1.exphosted.com"]
  [prdweb1.exphosted.com] executing command
 *** [err :: prdweb1.exphosted.com] rake aborted!
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] production database is not configured

 * executing `deploy:migrate'
 * executing "cd /deploy/crossbow/releases/20110525215013; bundle exec rake RAILS_ENV=production  db:migrate"
  servers: ["prdweb1.exphosted.com"]
  [prdweb1.exphosted.com] executing command
 *** [err :: prdweb1.exphosted.com] rake aborted!
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] No slaves databases defined for environment: production

 * executing `deploy:migrate'
 * executing "cd /deploy/crossbow/releases/20110525220110; bundle exec rake RAILS_ENV=production  db:migrate"
  servers: ["prdweb1.exphosted.com"]
  [prdweb1.exphosted.com] executing command
 *** [err :: prdweb1.exphosted.com] rake aborted!
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] Access denied for user 'cbprod'@'localhost' (using password: YES)

 *** [out :: prdweb1.exphosted.com] ==  AddDescriptionToCompany: migrated (0.0088s) ===============================
 *** [err :: prdweb1.exphosted.com] rake aborted!
 *** [err :: prdweb1.exphosted.com] An error has occurred, all later migrations canceled:
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] Constant CreateSelections from create_selections.rb not found
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] (See full trace by running task with --trace)
 command finished in 23233ms
 failed: "sh -c 'cd /deploy/crossbow/releases/20110525220437; bundle exec rake RAILS_ENV=production  db:migrate'" on prdweb1.exphosted.com

 * executing `deploy:migrate'
 * executing "cd /deploy/crossbow/releases/20110526161732; bundle exec rake RAILS_ENV=production  db:migrate"
  servers: ["prdweb1.exphosted.com"]
  [prdweb1.exphosted.com] executing command
 *** [err :: prdweb1.exphosted.com] rake aborted!
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com]
 *** [err :: prdweb1.exphosted.com] (See full trace by running task with --trace)
 *** [err :: prdweb1.exphosted.com]
 ** [out :: prdweb1.exphosted.com] (in /deploy/crossbow/releases/20110526161732)
 command finished in 13643ms
 failed: "sh -c 'cd /deploy/crossbow/releases/20110526161732; bundle exec rake RAILS_ENV=production  db:migrate'" on prdweb1.exphosted.com