If you have 512 MB of SWAP or below you need to increase the SWAP

$> sudo dd if=/dev/zero of=/swap bs=1M count=1024
$> sudo mkswap /swap
$> sudo swapon /swap

To make permanent, add this line to /etc/fstab

/swap swap swap sw 0 0

Install Passenger

$> gem install passenger
$> apt-get install apache2-threaded-dev libapr1-dev libaprutil1-dev
$> passenger-install-apache2-module

At the end it will display for you what to add to apache global conf file, in my case :

LoadModule passenger_module /usr/local/lib/ruby/gems/2.1.0/gems/passenger-5.0.30/buildout/apache2/mod_passenger.so
 <IfModule mod_passenger.c>
 PassengerRoot /usr/local/lib/ruby/gems/2.1.0/gems/passenger-5.0.30
 PassengerDefaultRuby /usr/local/bin/ruby
 </IfModule>

Also put something similar to this in the virtual host Apache config :

DocumentRoot /home/cbuy/public_html/public
RailsEnv production
ErrorLog /var/log/virtualmin/community-buy.ca_error_log
CustomLog /var/log/virtualmin/community-buy.ca_access_log combined
ScriptAlias /cgi-bin/ /home/cbuy/cgi-bin/
ScriptAlias /awstats/ /home/cbuy/cgi-bin/
DirectoryIndex index.html index.htm index.php index.php4 index.php5
<Directory /home/cbuy/public_html/public>
allow from all
AllowOverride All
Options FollowSymLinks -MultiViews Indexes
</Directory>

Restart Apache

Troubleshooting

Generic error

Check where you can access the log file with

$> passenger-config --detect-apache2

"We're sorry, but something went wrong."

Edit Apache VirtualHost configuration to run development mode to see the error:

RailsEnv development

Then restart Apache.

"This web application process is being run as user 'nobody' and group 'nogroup' and must be able to access its application root directory"

chown your app dir so that your user can access it. If you use virtualmin that is your domain account user.

[2016-09-07 23:24:59] ERROR RuntimeError: Missing `secret_token` and `secret_key_base` for 'production' environment, set these values in `config/secrets.yml`

/usr/local/lib/ruby/gems/2.1.0/gems/railties-4.2.3/lib/rails/application.rb:534:in `validate_secret_key_config!'
/usr/local/lib/ruby/gems/2.1.0/gems/railties-4.2.3/lib/rails/application.rb:246:in `env_config'
/usr/local/lib/ruby/gems/2.1.0/gems/railties-4.2.3/lib/rails/engine.rb:514:in `call'
/usr/local/lib/ruby/gems/2.1.0/gems/railties-4.2.3/lib/rails/application.rb:165:in `call'
/usr/local/lib/ruby/gems/2.1.0/gems/rack-1.6.4/lib/rack/lock.rb:17:in `call'
/usr/local/lib/ruby/gems/2.1.0/gems/rack-1.6.4/lib/rack/content_length.rb:15:in `call'
/usr/local/lib/ruby/gems/2.1.0/gems/rack-1.6.4/lib/rack/handler/webrick.rb:88:in `service'
/usr/local/lib/ruby/2.1.0/webrick/httpserver.rb:138:in `service'
/usr/local/lib/ruby/2.1.0/webrick/httpserver.rb:94:in `run'
/usr/local/lib/ruby/2.1.0/webrick/server.rb:295:in `block in start_thread'

Problem: Only accessible on localhost

Solution: RAILS_ENV=production rails server -b 0.0.0.0

Problem

Forbidden

You don't have permission to access / on this server.

Solution

You might have uploaded files as root or such that is not accessible by the Apache/passenger.

chown -R <user>:<user> /home/<user>/public_html

Problem : It doesnt work

Solution

RAILS_ENV=production bundle exec rake assets:precompile

config.serve_static_assets = true