Capistrano Switchtower

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Capistrano (Switchtower)

• Automating Application Deployment

By Gregg Pollack
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Deployment isnt that complex, right?

• Simple sites are easy
• One Database
• One Webserver
• One Application

• Multiple Sites?

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Intro to Capistrano

• What is Capistrano?
• Can be used everywhere
• Lots of Assumptions

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Installing Capistrano

• Gem install capistrano
• cap h to see commands
• Now to apply it to an application
• cap apply-to /path/to/my/app ApplicationName
• Creates two files
• config/deploy.rb
• Lib/tasks/Capistrano.rake

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Configure Capistrano

• Edit deploy.rb to match your apps setup
• Youll need to specify the servers, repository
  location and deployment path at minimum
• Defaults to SVN, normal SSH port, key in user
  home, SCM executable on PATH, etc.
• When you first start, youll probably only have
  one server fulfill the DB, web and app roles.

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My Modifications to deploy.rb

• set application, "captest"
• set repository, "https//pollack.textdriven.com/s
  vn/captest"
• role web, "burnaby.textdrive.com"
• role app, "burnaby.textdrive.com"
• role db, "burnaby.textdrive.com"
• set deploy_to, "/users/home/patched/sites/captest
  "
• set user, "patched"
• set svn_username, "captest"
• set svn_password, "captest"
• desc "Restart the webserver/fcgi procs, however
  you do it"
• task restart, roles gt app do
• Im not going to restart anything for this
  example
• end
• task after_deploy, roles gt app do
• Set my new dispatch.fcgi to be executable
• run "chmod 755 deploy_to/current/public/dispat
  ch.fcgi"
• end

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Setup

• rake remoteexec ACTIONsetup
• Sets up the base directories

This creates /sites/captest/releases /sites/captes
t/shared /sites/captest/shared/log /sites/captest/
shared/system
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Deployment Structure
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Lets Deploy!

• Rake --tasks to see all our options
• Rake deploy to push a version
• Rake rollback to rollback

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How Ive hacked Capistrano

• desc "My Simple Deploy"
• task deploy, roles gt app do
• run "svn update deploy_to"
• run "cd deploy_to "
• "rake RAILS_ENVproduction migrate"
• run "ruby deploy_to/script/process/reaper
  -a reload -r .pid"
• end

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Documentation on Capistrano

• Online Book
• http//manuals.rubyonrails.com/read/book/17