capistrano - atlanta ruby user group.pdf

8/14/2019 Capistrano - Atlanta Ruby User Group.pdf

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CapistranoDeployment Sucks. Capistrano Swallows.Charles Brian Quinn

Atlanta Ruby User Group


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Whats it? Whos it?

Automated Web Application Deployment Another tool extracted from Basecamp by

Jamis Buck and DHH

Uses Rake and Net:SSH cleverly

Convention over Configuration


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Without Capistrano

SSH into app servercd into /path/my/app

move app elsewhereget latest version of appsetup database.ymlsetup any other shared resourcesmigrate databasesrestart application serversrestart web server

repeat for all servers (!)if an error introduced, move old back....cry a little bit not cool


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With Capistrano

$ rake remote:deploy

$ rake remote:rollback

cool (calm and assertive)


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The Mental Model

Capistrano is your actor He assumes roles, and executes tasks It helps to deploy an app once manually to

see whats involved


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Go Git it

$ gem install capistrano

(requires needle and Net:SSH)

optionally termios for hiding passwords (linux only)

apply to your app:$ cap --apply-to /my/app MyApp


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deploy.rb

The configuration or recipe file:

variablesset :deploy_to, "/var/www/apps/#{application}"

rolesrole :web, "bristol.highgroove.com"

tasksdesc "A Task that does something cool"task :something_cool, :roles => [:app, :db] do

# ...

end


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the minimum to play

set :application, racecar

set :repository, http://svn.highgroove.com/racecar/trunk

role :app, daytona.highgroove.com

role :web, daytona.highgroove.com

role :db, daytona.highgroove.com, :primary =>

true
http://svn.example.org/app-name/trunkhttp://svn.example.org/app-name/trunkhttp://svn.example.org/app-name/trunkhttp://svn.example.org/app-name/trunk


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Task Dissected

desc "A task demonstrating the use of transactions."

task :long_deploy, :roles => :app do

transaction do update_code

disable_web

symlink

migrate

end

restart enable_web

end

Ruby DSLsRule!


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Built-in Tasks

deploy / cold_deploy / deploy_with_migrations

rollback

update / update_code / update_current cleanup disable_web / enable_web migrate restart / restart_web setup


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Out-of-the-box

Supports: subverison, darcs, perforce,bazaar, bazaar-NG

Default: restarts FCGIs and apache


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Set er up

$ rake remote:setup

or

$ rake remote:exec ACTION=setup


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Directory Structure[deploy_to] +- releases | +- 20050725121411 | +- 20050801090107 | +- 20050802231414 | ... | +- 20050824141402 | | +- Rakefile

| | | app | | | config | | | db | | | lib | | | log --> [deploy_to]/shared/log | | | public | | | +- ... | | | system --> [deploy_to]/shared/system

| | | ... | | | script | | | test | | | vendor | +- shared | +- log | +- system | + current --> [deploy_to]/releases/20050824141402


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Fun with Callbacks

Every task has before_ and after_

example:task :after_update_code, :roles => [:app, :db] do

database_yml

sudo "chmod -R +x #{release_path}/script/*"end


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Demo


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Tips n Tricks

$ rake remote:exec ACTION=show_tasks

interactive shell (new feature as of 1.2.0) mongrel_cluster by Bradley Taylor (overrides

spinner and restart for mongrel)

build config files using ERB or use put


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A tricked out setup

Check out:http://www.slingshothosting.com/files/apache2_2_mongrel_deploy.rb

And the public svn repo:http://svn.highgroove.com/deployment/

Sets up apache 2.1+ mod_proxy_balancer,mongrel configs, crontabs, ferret_index,rails_cron, etc. and more!
https://bristol.highgroove.com:8443/deployment/http://www.slingshothosting.com/files/apache2_2_mongrel_deploy.rbhttps://bristol.highgroove.com:8443/deployment/https://bristol.highgroove.com:8443/deployment/http://www.slingshothosting.com/files/apache2_2_mongrel_deploy.rbhttp://www.slingshothosting.com/files/apache2_2_mongrel_deploy.rb


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Heartbeat

Making Deployment actually Push-Button


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www.heartbeathq.com

More Plugging and Promotion

Launching Real Soon(tm)

Takes in a svn repository, reads deploymentfile -- allows selection of tasks, and *real*push-button deployment

Also runs remote tasks, and monitors URLs Demo
http://www.heartbeathq.com/http://www.heartbeathq.com/


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For more on Cap

The [outdated] manual:http://manuals.rubyonrails.com/read/book/17

The GoogleGroup:http://groups.google.com/group/capistrano Jamis blog:

http://weblog.jamisbuck.org/

A Cheatsheet:http://dizzy.co.uk/cheatsheets/
http://dizzy.co.uk/cheatsheets/http://weblog.jamisbuck.org/http://groups.google.com/group/capistranohttp://manuals.rubyonrails.com/read/book/17http://dizzy.co.uk/cheatsheets/http://dizzy.co.uk/cheatsheets/http://weblog.jamisbuck.org/http://weblog.jamisbuck.org/http://groups.google.com/group/capistranohttp://groups.google.com/group/capistranohttp://manuals.rubyonrails.com/read/book/17http://manuals.rubyonrails.com/read/book/17

capistrano - atlanta ruby user group.pdf

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