Deploying Rails

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1 Deploying with git

heroku is one "Platform as a Service" provider that offers to host your rails app. Heroku uses git to push the code to the production server.

(See also Railsbridge Installfest: Create A Heroku Account and Railsbridge Installfest: Deploy A Rails App )

• create an account on https://heroku.com
• add your public key to your heroku account
• install the heroku toolbelt on your local development machine

in your rails app, which is already using git:

• heroku create
• make some changes in the Gemfile (rubyracer, pg instead of sqlite)
• don't forget to commit all changes!
• git push heroku master
• heroku run rake db:migrate
• heroku open
• heroku logs

That's it. You should now have an app with a very strange URL, like http://mighty-shore-1497.herokuapp.com/

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2 Public Key Authentication in SSH

(See also Railsbridge Installfest)

• learn about ssh
• if you have a public + private key pair
  • id_rsa
  • id_rsa.pub
• and your private key is on your local computer
  • stored in ~/.ssh/id_rsa
• and your public key is on the server
  • stored in ~/.ssh/authorized_keys2
• then ssh will let you log in without giving a password

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2.1 deploying with a deploy-user

• alice and bob both want to deploy project x
• deploy_x is set up as an account on the server
• alice adds her public key to ~deploy_x/.ssh/authorized_keys2
• bob adds his public key to ~deploy_x/.ssh/authorized_keys2
• both can deploy (from different machines) using the same capistrano setup

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2.2 authorized_keys2

ssh-rsa AAAAB3NzaC...2EAAAABI== alice@fh-salzburg.ac.at
ssh-rsa AAAAB8NzaC...DVj3R4Ww== bob@fh-salzburg.ac.at

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3 How to run Rails

• WEBrick (built in web server)
• apache/nginx + mod_passenger
• apache/nginx + mod_passenger + capistrano

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3.1 WEBrick

• rails s

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3.2 mod_passenger

• install mod_passenger
• upload your code
• create files not in git (e.g. database.yml)
• apache config:
  • set DocumentRoot to public/
  • set RailsEnv production
• restart apache
• if you change the code:
  • touch tmp/restart.txt to force reload of code

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4 Deploying with Capistrano

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4.1 WARNING

• capistrano is a command line tool
• you need to read the output!
• you need to read every line of the output!
• you seriously need to read every line of the output!

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4.2 capistrano assumptions

• You are using SSH to access your remote machines
• your remote servers have a shell called sh
• authentication through password or public key
• Capistrano reads its instructions from a capfile

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4.3 how to install

$ sudo gem install capistrano
Fetching: capistrano-2.13.5.gem (100%)
Successfully installed capistrano-2.13.5
1 gem installed
$ $ cap install
mkdir -p config/deploy
create config/deploy.rb
create config/deploy/staging.rb
create config/deploy/production.rb
mkdir -p lib/capistrano/tasks
create Capfile
Capified

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4.4 configuration in config/deploy.rb

local information, see our wiki

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4.5 example task in Capfile

task :display_free_disk_space do
  run "df -h"
end

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4.6 prepare capistranoe

$ cap production git:check
$ scp config/database.yml deployuser@server:/var/www/.../shared/config
$ scp config/secrets.yml deployuser@server:/var/www/.../shared/config
$ cap production deploy

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4.7 run a capistrano task

$ cap production deploy
$ cap display_free_disk_space
* 2012-11-29 05:34:45 executing 'display_free_disk_space'
* executing "df -h"
  servers: ["multimediaart.at"]
  Password: ****
  [multimediaart.at] executing command
** [out :: multimediaart.at] Size  Used Avail Use% Mounted on
** [out :: multimediaart.at] 98G   70G   24G  75% /var/www
  command finished in 165ms

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4.8 capistrano folders

read the logfile, try to find out how capistrano lays out the folders

• current --> links to a release
• release
  • 20121201113038
  • 20121201150544
• shared
  • assets
  • bundle
  • log
  • pids
  • system

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4.9 my first deploy

$ cap deploy:setup
$ cap deploy:check
$ cap deploy:cold
$ cap deploy:upload FILES='config/database.yml'