Deploying Rails App to AWS EC2 Ubuntu Server With Capistrano

Techie     January 2023

Introduction

Deploying application updates takes multiple steps. Performing all these steps every time you want to deploy application updates is time-consuming and error-prone. This section will guide you on how to automate the deployment of application updates through Capistrano.

Capistrano is a popular task automation tool among Ruby developers. Once Capistrano is set up, deploying further application updates only takes a single command.


Part A

ssh into your server and:

  1. Install Ruby

  2. Install MySQL

  3. Install nginx and passenger


Part B

1 . Initializing Capistrano

The first thing you need to do is to install Capistrano into your rails project.

i). Open the Gemfile and add:

# Gemfile

group :production do
  gem 'capistrano'
  gem 'capistrano-bundler'
  gem 'capistrano-passenger', '>= 0.1.1'
  gem 'capistrano-rails'
  # Because we’re using rbenv on our EC2 Server
  gem 'capistrano-rbenv'
end


ii) Install the gem bundle and initialize Capistrano:

$ bundle install

$ bundle exec cap install


2 . Editing Capfile

Capfile is the Capistrano entry point. It defines what recipes to load. You must edit it to load the recipes you need.

We will want Capistrano to automatically run bundle install, and we will want Capistrano to automatically tell Passenger to restart our app. These are taken care of by the capistrano-bundler and capistrano-passenger recipes. So make sure that the following lines are uncommented:

# Capfile

#Because the server uses rbenv
require "capistrano/rbenv"

require "capistrano/bundler"
# require "capistrano/rails/assets" # hashed out because of server's assets precompile issues
require "capistrano/rails/migrations"
require "capistrano/passenger"


3 . Editing config/deploy.rb

The next step is to edit config/deploy.rb. This file contains configuration values that control how the loaded recipes should do their jobs. It also defines additional commands to be executed on servers. You must edit it according to your situation.

# config/deploy.rb


# config valid for current version and patch releases of Capistrano
# Remove the lock statement since already serves as a mechanism to lock down gem
# lock "~> 3.11.0"


# Set repo_url to your Git repository's URL
set :application, "myapp"
set :repo_url, "git@github.com:yourgitusername/myapp.git"


# Default deploy_to directory is /var/www/my_app_name
 set :deploy_to, "/home/username/projects/myapp"


# set linked_files and linked_dirs

set :linked_files, fetch(:linked_files, []).push('config/database.yml', 'config/secrets.yml', '.env')
set :linked_dirs, fetch(:linked_dirs, []).push('log', 'tmp/pids', 'tmp/cache', 'tmp/sockets', 'vendor/bundle', 'public/system', 'public/uploads')



namespace :deploy do

  after :restart, :clear_cache do
    on roles(:web), in: :groups, limit: 3, wait: 10 do
      # Here we can do anything such as:
      # within release_path do
      #   execute :rake, 'cache:clear'
      # end
    end
  end

end


4 . Editing config/deploy/production.rb

The next step is to edit config/deploy/production.rb. This file defines the servers that Capistrano should deploy to, in the form of SSH login information.

Our server is on Amazon EC2, so be sure to uncomment the set :ssh_options call and point the keys option to your Amazon EC2 key file. Also set the auth_methods option to %w(publickey password).

# config/deploy/production.rb

# role-based syntax
# ==================

# Single server
# Replace with your server's IP and user
 role :app, %w{username@54.82.83.53}
 role :web, %w{username@54.82.83.53}
 role :db,  %w{username@54.82.83.53}


# Custom SSH Options
# ==================
# --------------
 set :ssh_options, {
  keys: %w(/home/username/somepath/your_key_pair.pem),
  forward_agent: false,
  auth_methods: %w(publickey password)
}


5 . Setting up a basic directory structure

Run the following commands on the server to setup a basic directory structure that Capistrano can work with.

$ sudo mkdir -p /home/username/projects/myapp/shared
$ sudo chown myappuser: /home/username/projects/myapp /home/username/projects/myapp/shared


6 . Create initial configuration files

The app expects a config/database.yml and a config/secrets.yml files. The contents of these configuration files are only known to the server and persist across application releases. The shared directory is the perfect place to place them. And as configured before in config/deploy.rb, Capistrano will automatically create symlinks within the release directory to those files.

i) On the server, create the shared/config directory and add database.yml and secrets.yml files inside:

$ sudo mkdir -p /home/username/projects/myapp/shared/config

$ sudo touch /home/username/projects/myapp/shared/config/database.yml && sudo touch /home/username/projects/myapp/shared/config/secrets.yml


ii). Then fix and tighten permissions:

sudo chown -R username: /home/username/projects/myapp/shared/config
chmod 600 /home/username/projects/myapp/shared/config/database.yml
chmod 600 /home/username/projects/myapp/shared/config/secrets.yml


iii). edit database.yml file

 
  
production:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: myapp_database
  pool: 5
  username: db_username
  password: db_password


iv). On your development machine, generate the secret key and add it to config/initializers/secret_token.rb file.

 
  
$ rails secret


 
# config/initializers/secret_token.rb

# Be sure to restart your server when you modify this file.

# Your secret key is used for verifying the integrity of signed cookies.
# If you change this key, all old signed cookies will become invalid!

# Make sure the secret is at least 30 characters and all random,
# no regular words or you'll be exposed to dictionary attacks.
# You can use `rake secret` to generate a secure secret key.

# Make sure your secret_key_base is kept private
# if you're sharing your code publicly.
Rails.application.config.secret_key_base = '90a82db7702c2d0af8a5ad715962116b8fffaf7bb833162a32ef71d345845e424de9e0ecda1dbd81191201ecbtfc09c7f6a747eb17d7cc111490914df62b2c09'


v). Add the secret key in the secrets.yml file on the server

  
 
90a82db7702c2d0af8a5ad715962116b8fffaf7bb833162a32ef71d345845e424de9e0ecda1dbd81191201ecbtfc09c7f6a747eb17d7cc111490914df62b2c09


7 . Deploying a new release

You are now ready to deploy a new release using Capistrano! On your local computer, make a random change in your application, then commit and push your changes. Next, run Capistrano to start the deployment:

$ bundle exec cap production deploy

You have now automated deployments using Capistrano!


Thanks for reading, see you in the next one!