Capistrano 2
Rocks my world
Graeme Mathieson, Rubaidh Ltd
<mathie@rubaidh.com>
http://woss.name/ & http://www.rubaidh.com/

What’s the plan?
• So, what is it?
• Installing 2.0
• What’s new in Cap 2?
• Stuff I’ve done with cap 2

What is it?
• A Rails deployment tool
• A Java deployment tool
• A troubleshooting tool
• An ad-hoc systems management tool

Without a Capfile
$ cap2 invoke COMMAND=uname HOSTS=macallan,cardhu
* executing `invoke'
* executing \"uname\"
servers: [\"macallan\", \"cardhu\"]
[macallan] executing command
[cardhu] executing command
** [out :: cardhu] SunOS
** [out :: macallan] Linux
command finished
$

Using cap shell
$ cap2 shell HOSTS=balvenie,cardhu
* executing `shell'
cap> uptime
[establishing connection(s) to balvenie, cardhu]
** [out :: balvenie] 19:33:52 up 211 days, 7:25, 1 user, load
average: 0.06, 0.07, 0.07
** [out :: cardhu] 7:33pm up 10 day(s), 6:47, 2 users, load
average: 0.18, 0.16, 0.15
cap> uname -r
** [out :: balvenie] 2.4.21-47.0.1.EL
** [out :: cardhu] 5.10
cap>

Installing 2.0
$ gem install -y net-ssh net-ftp highline
[ ... ]
$ gem install -s http://gems.rubyonrails.com/ capistrano
[ ... ]
Done!

Co-existing with 1.x
# In ~/.bashrc
alias cap1=\"`which cap` _1.4.1_\"
alias cap2=\"`which cap`\"
alias cap=\"echo 'Please explicitly choose cap1 or cap2.'\"

New in 2.0?
• More rake-like
- Use `cap2 -T` to list tasks
- Namespaces
• Deployment strategies
• Dependencies
• Generic hooks

New task names
• deploy well, umm, deploy
• deploy_with_migrations deploy:migrations
• diff_from_last_deploy deploy:pending:diff
• setup deploy:setup
• Same idea, just with namespaces

New Deployment Tasks
• Subversion log of undeployed changes
• deploy:pending
• Command, gem, file, directory dependencies
• deploy:check

What I’ve been up to

Recipes in plugins
# New Capfile
Dir['vendor/plugins/*/recipes'].each do |plugin|
load_paths << plugin
end
load 'deploy' if respond_to?(:namespace)
load 'config/deploy'

Daemon Strategies
• Default uses spin/spawner/reaper
• Solaris Service Management Framework
• runit
• daemontools
• Autogenerate script/spin

Staging
• Separate clusters for staging & deployment
• Use svnmerge to manage branches
• Trunk is deployed to staging server
• Production branch gets deployed live

General Strategy
• Create a rake task to do what you want.
• Create a Capistrano task that runs the rake
task.
• Hook it into the deployment.

DB Backup - Rake
desc \"Dumps the database into db/env-data.sql.\"
task :dump => :environment do
abc = ActiveRecord::Base.configurations[RAILS_ENV]
cmd = ['mysqldump']
cmd << \"--host='#{abc['host']}'\" unless abc['host'].blank?
cmd << \"--user='#{abc['username']}'\"
cmd << \"--password='#{abc['password']}'\"
cmd << abc['database']
cmd << \" | gzip > #{RAILS_ROOT}/db/#{RAILS_ENV}-data.sql.gz\"
sh cmd.flatten.join ' '
end

DB Backup - Capfile
desc “Back up the production database”
task :backup, :roles => :db, :only => { :primary => true } do
rake = fetch(:rake, 'rake')
rails_env = fetch(:rails_env, 'production')
run \"cd #{current_path}; #{rake} RAILS_ENV=#{rails_env} db:dump\"
get \"#{current_path}/db/#{rails_env}-data.sql.gz\", \"db/#
{rails_env}-data.sql.gz\"
end

Hook into deployment
before \"deploy:migrate\", \"db:backup\"

All in a plugin
$ script/plugin install -x \\
http://svn.rubaidh.com/plugins/trunk/rubaidh_platform

“I checked out your slides, and they look great!
Best of luck on your presentation.”
- Jamis Buck

What else do you want
to know?