How to deploy a Ruby on Rails app to Heroku

Published: 2015-07-25

By: MJ Rossetti

Category:
Technologies:

This document describes the process of deploying a Ruby on Rails application to a production server hosted by Heroku.

Prerequisites

Download heroku toolbelt to enable heroku command line tools.

heroku login
cd ~/myapp

Configuration

Create and configure a new heroku application.

heroku create
heroku apps:rename myapp
heroku config:set KEY1=VALUE1 [KEY2=VALUE2 ...]
# heroku domains:add example.com

Custom Buildpacks

If your rails app uses node package manager to manage front-end dependencies, configure heroku to use a custom buildpack called buildpack-multi, which facilitates usage of multiple heroku buildpacks.

heroku config:add BUILDPACK_URL=https://github.com/ddollar/heroku-buildpack-multi.git

Specify buildpacks in a .buildpacks file:

https://github.com/heroku/heroku-buildpack-nodejs
https://github.com/heroku/heroku-buildpack-ruby

NOTE: the practice of setting BUILDPACK_URL is deprecated. The preferred method is heroku buildpacks:set https://github.com/ddollar/heroku-buildpack-multi.git.

Deployment

From master branch:

git push heroku master

From another branch:

git push heroku mybranch:master

Suppress Warnings

Add to Gemfile:

ruby "2.2.0"
group :production do
  gem 'rails_12factor'
  gem 'puma'
end

Add a Procfile:

web: bundle exec puma -C config/puma.rb

Add a config/puma.rb:

workers Integer(ENV['WEB_CONCURRENCY'] || 2)
threads_count = Integer(ENV['MAX_THREADS'] || 5)
threads threads_count, threads_count

preload_app!

rackup      DefaultRackup
port        ENV['PORT']     || 3000
environment ENV['RACK_ENV'] || 'development'

on_worker_boot do
  # Worker specific setup for Rails 4.1+
  # See: https://devcenter.heroku.com/articles/deploying-rails-applications-with-the-puma-web-server#on-worker-boot
  ActiveRecord::Base.establish_connection
end

Also make sure there is a root route set in config/routes.rb.

Add-ons

heroku addons

Database

Follow the PostgreSQL or MySQL instructions, depending on your database choice.

For further instructions, see Working with Databases on Heroku.

PostgreSQL

heroku pg:credentials DATABASE
heroku pg:reset DATABASE
heroku run bundle exec rake db:migrate
heroku run bundle exec rake db:seed

heroku pg:reset DATABASE is roughly equivalent to rake db:drop && rake db:create

Use heroku pg:psql to execute custom SQL queries in a production database console.

MySQL

Revise database.yml:

production:
  url: <%= ENV['DATABASE_URL'] %>

Create a new DATABASE_URL heroku config variable as a duplicate of the CLEARDB_DATABASE_URL except change the mysql part to mysql2. This avoids a mysql gem installation error.

heroku run bundle exec rake db:migrate
heroku run bundle exec rake db:seed

NOTE: you may have to run these bundle commands within a heroku run bash prompt…

Tasks

heroku addons:create scheduler
heroku addons:open scheduler

Mail

heroku addons:create sendgrid:starter
heroku addons:open sendgrid
heroku config:get SENDGRID_USERNAME
heroku config:get SENDGRID_PASSWORD

Add to config/environments/production.rb:

config.action_mailer.default_url_options = { host: 'my-app-name.herokuapp.com' }

# Send mail through sendgrid smtp on production.
config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  :address        => 'smtp.sendgrid.net',
  :port           => '587',
  :authentication => :plain,
  :user_name      => ENV['SENDGRID_USERNAME'],
  :password       => ENV['SENDGRID_PASSWORD'],
  :domain         => 'heroku.com',
  :enable_starttls_auto => true
}

Debugging

heroku pg:info
heroku logs
heroku logs -t # for tail
heroku logs -n 1500
heroku run bash
heroku run console
heroku pg:backups capture
heroku ps  # get the process number, then stop with ...
heroku ps:stop scheduler.6531

Maintenance

Database Upgrades

heroku addons:create heroku-postgresql:hobby-basic # or... heroku addons:create heroku-postgresql:standard-0
heroku pg:wait # only if upgrading to standard tier or higher
heroku maintenance:on
heroku ps:scale worker=0
heroku pg:copy DATABASE_URL HEROKU_POSTGRESQL_CHARCOAL_URL # where HEROKU_POSTGRESQL_CHARCOAL_URL is the name of the new database
heroku pg:promote HEROKU_POSTGRESQL_CHARCOAL_URL
heroku ps:scale worker=1
heroku maintenance:off

Database Backups

Initiate a new PG Backup from the Heroku Postgres console and click “Download” when it’s ready.

Restore production database on local machine.

psql
DROP DATABASE IF EXISTS my_app_snapshot;
CREATE DATABASE my_app_snapshot;
\q

pg_restore --verbose --clean --no-acl --no-owner -h localhost -U my_db_user -d my_app_snapshot latest.dump

Back-up and store the database.

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