Let's run a Rails server using Puma and Apache. We will use Apache's reverse proxy and Puma's Jungle service.

Passenger vs Puma vs Unicorn

As for 2019, there are three main options to serve a Rails application:

• Phusion Passenger
• Puma
• Unicorn

Phusion Passenger is an Apache/Nginx module. It works just like mod_php (it is sometimes referred to mod_rails). Passenger is probably the most used solution in production environments.

Puma and Unicorn, are stand-alone web servers. If you call them inside a Rails project root folder, they will listen to the port 80 (or any other you specify), wait for web connections, run the Rails code and answer to the browser – no need for Apache, Nginx, or anything else.

This tutorial shows how to run Puma with Apache. The only way to do this is through a reverse proxy, as there are no FastCGI or Apache/Nginx modules available.

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1. Add puma to Gemfile

WARNING

Ignore this entire step 1 for Rails 5+, as Puma is the default webserver.

cd /var/www/site-1
nano Gemfile

# Gemfile
source 'https://rubygems.org'
...
gem 'puma'
...

bundle install

2. Create/replace contents of puma.rb

First, check how many CPU cores you have:

grep -c processor /proc/cpuinfo
  2

Set ./config/puma.rb:

# /var/www/site-1/config/puma.rb
# Change to match your CPU core count
workers 2

# Min and Max threads per worker
threads 1, 6

# Project folder
app_dir = File.expand_path("../..", __FILE__)

# Default to production
rails_env = ENV.fetch("RAILS_ENV") { "production" }
environment rails_env

# Set up socket location
bind "unix://#{app_dir}/tmp/puma/puma.sock"

# Logs
stdout_redirect "#{app_dir}/log/puma.stdout.log", "#{app_dir}/log/puma.stderr.log", true

# Set master PID and state locations
pidfile "#{app_dir}/tmp/puma/pid"
state_path "#{app_dir}/tmp/puma/state"

# Establish db connection for new processes
on_worker_boot do
  require "active_record"
  ActiveSupport.on_load(:active_record) do
    ActiveRecord::Base.establish_connection(YAML.load_file("#{app_dir}/config/database.yml")[rails_env])
  end
end

# Allow puma to be restarted by `rails restart` command.
plugin :tmp_restart

# Puma control rack application
activate_control_app

Adjust the number of workers according to the number of CPU cores of your server. This will maximize performance.

3. Create a ./tmp/puma folder

sudo mkdir -p ./tmp/puma

This folder will contain the PID/state/socket files. These file paths are set on puma.rb and are expected to be defined as this on the init scripts.

4. Permissions: Add your user to www-data group

Add your user to the www-data group in order to write/read the project folder:

sudo usermod -a -G www-data daniel

Replace daniel with the owner of the project files.

Check your groups:

id
  uid=1000(daniel) gid=1000(daniel) groups=1000(daniel),4(adm),24(cdrom),27(sudo),30(dip),33(www-data),46(plugdev),118(lpadmin),129(sambashare),1001(rvm)

If www-data group doesn't appear for you, do a logout/login. Close/open shell won't work.

5. Permissions: Set group permissions

Set group ID on the directory - all new files and sub-directories created within the current directory inherit the group ID:

sudo chmod g+s /var/www/site-1
sudo find /var/www/site-1 -type d -exec chmod 2775 {} \;

Set write permissions to the group:

sudo chown -R www-data:www-data /var/www/site-1
sudo chmod -R g+w /var/www/site-1
sudo find /var/www/site-1 -type f -exec chmod ug+rw {} \;

6. Download init scripts (Jungle)

cd ~
wget https://raw.githubusercontent.com/puma/puma/master/tools/jungle/init.d/puma
wget https://raw.githubusercontent.com/puma/puma/master/tools/jungle/init.d/run-puma

7. Install init scripts

# Copy the init script to services directory
sudo mv puma /etc/init.d
sudo chmod +x /etc/init.d/puma

# Make it start at boot time.
sudo update-rc.d -f puma defaults

# Move the Puma runner to an accessible location
sudo mv run-puma /usr/local/bin
sudo chmod +x /usr/local/bin/run-puma

# Create an empty configuration file
sudo touch /etc/puma.conf

8. Set which projects will be managed by Jungle

# /etc/puma.conf
/var/www/site-1,www-data
#/var/www/site-2,www-data
#/var/www/site-3,www-data

9. Start Puma (Jungle) service

sudo service puma restart

Check socket:

ls -lh /var/www/site-1/tmp/puma/puma.sock

If the file doesn't exist, check the logs (./log/puma*)

10. Test if service can be stopped

To be able to stop / restart the service, the root user must have Ruby and Puma installed:

sudo pumactl -v

If you see the "command not found" error, you need to install Puma for the root user:

A quick fix is to run sudo apt install puma. This won't mess your rbenv/rvm.

11. Install mod_proxy and mod_proxy_http

sudo a2enmod proxy
sudo a2enmod proxy_http
sudo service apache2 reload

12. Edit your domain #1 configuration

File /etc/apache2/sites-available/site-1.conf:

<VirtualHost *:80>
  ServerName site-1.com
  ServerAlias www.site-1.com
  DocumentRoot /var/www/site-1/public

  <Location /assets>
    ProxyPass !
  </Location>
  <Location /system>
    ProxyPass !
  </Location>

  ProxyPass / unix:///var/www/site-1/tmp/puma/puma.sock|http://localhost/
  ProxyPassReverse / unix:///var/www/site-1/tmp/puma/puma.sock|http://localhost/
</VirtualHost>

Notice that ProxyPass ignores /assets and /system folders, so they won't be processed by Ruby.

13. Enable your domain #1 and restart Apache

sudo a2ensite site-1

apachectl -t
  Syntax Ok

sudo /etc/init.d/apache2 restart

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OPTIONAL: Using a different user other than www-data for Puma processes

As an example, let's create a deploy user for the Puma processes. We will also use a group with the same name, deploy.

All commands as root user

sudo su

Create the user/group

# create user deploy (password 102030)
useradd -m deploy -p 102030

# create group deploy
groupadd deploy

# add user to the group
usermod -a -G deploy deploy

Add it to RVM (if using RVM)

rvm group add rvm deploy

Change folder ownership

chown -R deploy:deploy /var/www/site-1

Change /etc/puma.conf

/var/www/site-1,deploy

Reload service

service puma restart

TIP

For extra security, set a different user for each Rails project.

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That's it. Now you can add another site just repeating the process.