Ubuntu Hardy - Apache, Rails and thin

Following from the thin web server for Ruby article, let's look at creating and configuring Apache to proxy to thin so we can serve our Ruby on Rails application.

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Prerequisites

To get the most out of this article you need to have a couple of things preinstalled:

Firstly, you need Apache installed (see this article) - if you don't require PHP then please feel free to leave that section out.

Secondly, you will need to have thin installed - as mentioned above, please see the Ubuntu Hardy - thin web server for Ruby article for more details.

Rails application

To start with, we will need a basic Ruby on Rails application. Move into your public_html folder (create one if you do not have one already):

cd ~/public_html

Then create a Rails application. We'll use the default sqlite database for this example:

rails railsapp

Apache modules

Apache will need the proxy and rewrite modules enabled.

Depending on your Apache install you may need to issue all the following commands:

sudo a2enmod proxy
sudo a2enmod proxy_balancer
sudo a2enmod proxy_http
sudo a2enmod rewrite

Once done, reload Apache:

sudo /etc/init.d/apache2 force-reload

Apache Virtual Host

So what's the plan?

Well, for our simple application we'll set 3 thin instances running from port 5000 and in production mode.

Let's start off by creating the virtual host:

sudo nano /etc/apache2/sites-available/domain.com

The following will suffice for a basic application:

<VirtualHost *:80>
  ServerName domain.com
  ServerAlias www.domain.com

  DocumentRoot /home/demo/public_html/railsapp/public

  RewriteEngine On

  <Proxy balancer://thinservers>
    BalancerMember http://127.0.0.1:5000
    BalancerMember http://127.0.0.1:5001
    BalancerMember http://127.0.0.1:5002
  </Proxy>

  # Redirect all non-static requests to thin
  RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f
  RewriteRule ^/(.*)$ balancer://thinservers%{REQUEST_URI} [P,QSA,L]

  ProxyPass / balancer://thinservers/
  ProxyPassReverse / balancer://thinservers/
  ProxyPreserveHost on

  <Proxy *>
    Order deny,allow
    Allow from all
  </Proxy>

  # Custom log file locations
  ErrorLog  /home/demo/public_html/railsapp/log/error.log
  CustomLog /home/demo/public_html/railsapp/log/access.log combined

</VirtualHost>

Familiar?

Does that look familiar?

Well, it is pretty much the same as the virtual host used to proxy to mongrel servers.

If you think about it, we don't need anything different as all we are doing is rerouting non-static requests to thin in the same way we would for mongrels.

Enable

Don't forget to enable the vhost:

sudo a2ensite domain.com

And restart Apache:

sudo /etc/init.d/apache2 reload

If you get any port and NameVirtualHost errors then please read the Apache Virtual Host article which will take you through setting up said details.

Thin configuration

Next we need to configure thin on our application.

To kill two birds with one stone, we'll go straight into creating an init.d file so the thin servers are started on a Slice reboot.

Remember we want 3 servers running sequentially from port 5000 in production mode:

sudo thin config -C /etc/thin/railsapp.yml -c /home/demo/public_html/railsapp/  --servers 3 -p 5000 -e production

Have a quick check of the file we created:

cat /etc/thin/railsapp.yml

the contents of which look good:

pid: tmp/pids/thin.pid
log: log/thin.log
timeout: 30
max_conns: 1024
port: 5000
max_persistent_conns: 512
chdir: /home/demo/public_html/railsapp
environment: production
servers: 3
address: 0.0.0.0
daemonize: true

Stating thin

Now we'ce created our init script, let's start it:

sudo /etc/init.d/thin start

The terminal output confirms the actions:

[start] /etc/thin/railsapp.yml ...
Starting server on 0.0.0.0:5000 ... 
Starting server on 0.0.0.0:5001 ... 
Starting server on 0.0.0.0:5002 ...

Cool.

Navigate

All that's left is to navigate to your domain:

http://www.domain.com

Where you will be greeted with the rails welcome page.

Restart

As we created an init script for the thin servers you can restart them in the normal way:

sudo /etc/init.d/thin restart

Summary

Setting up a virtual host to proxy to the thin web server is fairly simple.

Add to that the ease of installing and configuring thin, the whole process in very quick and very powerful.

PickledOnion