Capistrano 3 & Rails 4

Categories: ruby

Hello, today i am tell you about Capistrano 3 and Rails 4 setup. For those who never heard about Capistrano, this is deployment library which can be scripted on ruby, in any ways.

First of all Gemfile:

gem 'unicorn'

gem 'capistrano'
gem 'capistrano-rvm'
gem 'capistrano-bundler'
gem 'capistrano-rails'

After that add into Capfile some require string to previous install gems:

require 'capistrano/rvm'
require 'capistrano/bundler'
require 'capistrano/rails'

Next to deploy.rb:

set :application "your_app_name"
set :repo_url "your repository url"
set :branch 

Also you need to edit deploy/production.rb to setup production server hostname . Read full article to understain the key problem and solution for it …

Some rude code for task to unicorn managemnt in deploy.rb:

 desc 'Start application'
  task :start do
    on roles(:app), in: :sequence, wait: 5 do
      within release_path do 
        execute :bundle, "exec unicorn_rails -p 8801 -E production -D"
      end 
    end 
  end

  desc 'Stop application'
  task :stop do 
    on roles(:app) , in: :sequence, wait: 5 do
       within release_path do
         execute "cd #{fetch(:deploy_to)}/current && cat tmp/pids/unicorn.pid | xargs kill "
       end
    end
  end

After that you probably think that everything should go nice and smooth, but something goes painfull…

After trying to make cap production deploy:start your likely get message that says you don’t set SECRET_KEY_BASE into environment variable. And if you add it to .bashrc .bash_profile or .profile files everything goes the same way with message.

After several tests i am explain that SSHKit starts shell with non-interactive and non-login options. That is exaclty the reason why nothing goes load with dotfiles. The thing is that when shell starts with non-interactive and non-login options, no one dotfiles is going to load, and everyting you have is $BASH_ENV.

To more expose this situation you must see this picture:

bash strartup scheme

So what should you do next ?

sshd have a special option for this situation, - PermitUserEnvironment yes, you must set it in /etc/ssh/sshd_config

After that you can create ~/.ssh/environment and put into:

SECRET_KEY_BASE=66a2caf0d57e376cae89a297656c1ff68a7d9abac9ee61b13652e97a4983ac00c2cb468e30181ae224e5951609591374f9ba0a31a77ba36c4f6587c2afcafd2f

After that when you run cap production deploy:start to strart unicorn server, everything will be fine because SECRET_KEY_BASE will be loaded from ~/.ssh/environment file

Have fun with it.


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