on development

Puma, Nginx, Rails and Capistrano

I just set up another app for the umteenth time. Since we all do it a bit differently and it usually takes a couple of weeks or months between new deploys I thought I should document how I usually set up the servers with Ruby on Rails, Puma and Nginx.

Why Puma?

Puma uses very little memory compared to Unicorn and Passenger in the apps I have developed. My second choice would probably be passenger for stability and ease of configuration, but I when Passenger goes wrong it is hard to find the errors.

NginX is faster than Apache in most of my experiments, so I’ll go with that.

My setup

  • Ubuntu (latest LTS)
  • Ruby (with rbenv for easy version switching)
  • Capistrano (for speedy deploys)

Configuration

Capfile

To make Puma play nice with Nginx I use the following config in my Capfile

...
require 'capistrano/rbenv'
require 'capistrano/bundler'
require 'capistrano/rails/assets'
require 'capistrano/rails/migrations'

# Puma/nginx config
require 'capistrano/puma'
require 'capistrano/puma/workers'
require 'capistrano/puma/nginx'
...

Full Gist here

Gems

gem 'capistrano', require: false
gem 'capistrano-rails', require: false
gem 'capistrano-bundler', require: false
gem 'capistrano-rbenv', require: false
gem 'capistrano3-puma', github: "seuros/capistrano-puma"
gem 'puma'

Capistrano stages

My staging and production config looks like this:

# Common (deploy.rb)
set :rbenv_ruby, "#{File.read('.ruby-version').chomp}"
set :rbenv_type, :user
set :rbenv_map_bins, %w{rake gem bundle ruby rails}
set :puma_worker_timeout, 60
set :puma_init_active_record, true
set :puma_preload_app, true

# Stage specific (stagename.rb)
set :rails_env, 'staging'
set :puma_env, 'staging'

# Configure depending on server load
set :puma_threads, [0, 5]
set :puma_workers, 1

set :nginx_server_name, 'staging.example.com'

Generate server config

First, generate the templates locally rails g capistrano:nginx_puma:config

Then run this: bundle exec cap staging puma:config puma:nginx_config

This should generate two configuration files on your server. Now you should start up the puma instances with bundle exec cap staging deploy

And then reload nginx on the server with sudo service nginx reload.