Section 4.2. Common Configurations

4.3.1.2. Set Up Your Mongrel Cluster Config

We're going to use a simple cluster of two Mongrels, using mongrel_cluster . Here we simply run the cluster::configure command, then start the cluster.

$ cd ~/code/examples/duck
$ mongrel_rails cluster::configure -p 3000 -e production -a 127.0.0.1 -N 3
Writing configuration file to config/mongrel_cluster.yml.
$ mongrel_rails cluster::start
Starting 3 Mongrel servers...

4.3.1.3. Modify the Default Apache Config

We will add one line to the default Apache config http.conf (look in /usr/local/apache2/conf )

# Include an external config for our examples
Include /usr/local/apache2/conf/duck.conf

For the purpose of this example, we're going to put all new configuration details in a single file called duck.conf in the default Apache configuration directory ( /usr/local/apache2/conf/ ).

NameVirtualHost *:80
# Setup the cluster
<Proxy balancer://duck_cluster>
  BalancerMember http://127.0.0.1:3000
  BalancerMember http://127.0.0.1:3001
  BalancerMember http://127.0.0.1:3002
</Proxy>
# Setup the VirtualHost for your Rails application
<VirtualHost *:80>
  ServerAdmin duck@example.com
  ServerName localhost
  ServerAlias localhost
  DocumentRoot /Users/matt/code/examples/duck/public
  <Directory '/Users/matt/code/examples/duck/public'>
    Options FollowSymLinks
    AllowOverride None
    Order allow,deny
    Allow from all
  </Directory>

  
  ProxyPass / balancer://duck_cluster/
  ProxyPassReverse / balancer://duck_cluster/

  # Setup your Rewrite rules here
  RewriteEngine On
  
  # Rewrite index to check for static
  RewriteRule ^/$ /index.html [QSA] 
 
  # Send all requests that are not found as existing files to the cluster
  RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} ! -f
  RewriteRule ^/(.*)$ balancer://duck_cluster%{REQUEST_URI} [P,QSA,L]
  
  # Error logs
  ErrorLog /Users/matt/code/examples/duck/log/apache_error_log
  CustomLog /Users/matt/code/examples/duck/log/apache_access_log combined
</VirtualHost>

4.3.2. From Russia, with Love: Nginx ^[2]

^[2] This configuration is based on work by Ezra Zygmunowicz and has been used with permission.

One of the chieftains of the Rails deployment world, Ezra Zygmunowicz, found a Russian Web server that happens to be mature, feature-complete, and fast called Nginx (think "Engine X"). It has a low memory footprint, and the proxying is faster than Apache's mod_proxy_balancer . He worked with some fellow developers and managed to get the configuration worked out. There is a wiki for Nginx English Documentation (http://wiki.codemongers.com/Nginx) to help guide you through any changes you'd like to make for your own setup. You'll want to set up mongrel_cluster the same way we did in the previous section for Apache.

4.3.2.1. Install Nginx

Installing Nginx is straightforward. This will install it into /usr/local/nginx.

$ curl -O http://sysoev.ru/nginx/nginx-0.4.0.tar.gz
$ tar zxvf nginx-0.4.0.tar.gz
$ cd nginx-0.4.0
$ ./configure --sbin-path=/usr/local/sbin --with-http_ssl_module
$ make
$ sudo make install

4.3.2.2. Set Up the Nginx Config

Now we can use a nice configuration that Ezra has honed to a sharp edge. In this example we are saving this in our Rails application's config directory as nginx.conf .

# User and group to run as
user  matt matt;
# Number of nginx workers
worker_processes  2;
# pid of nginx master process
pid        logs/nginx.pid;
# Number of worker connections. 1024 is a good default
events {
  worker_connections  1024;
}
# start the http module where we config http access.
http {
  # Pull in mime-types. You can break out your config

  # into as many includes as you want to make it cleaner
  include       conf/mime.types;
  # set a default type for the rare situation that
  # nothing matches from the mime-type include
  default_type  application/octet-stream;
  # configure log format
  log_format  main  '$remote_addr - $remote_user [$time_local] $status '
                    '"$request" $body_bytes_sent "$http_referer" '
                    '"$http_user_agent" "http_x_forwarded_for" ';
  # main access log
  access_log  logs/access.log  main;
  # main error log
  error_log  logs/error.log debug;
  # OSX does not support sendfile.
  # Uncomment this if you're on linux or bsd
  #sendfile        on;
  # These are good default values.
  tcp_nopush         on;
  keepalive_timeout  65;
  tcp_nodelay        on;
  # this is where you define your mongrel clusters. 
  # you need one of these blocks for each cluster
  # and each one needs its own name to refer to it later.
  upstream mongrel {
      server 127.0.0.1:3001;
      server 127.0.0.1:3002;

      server 127.0.0.1:3003;
  }
  # output compression saves bandwidth 
  gzip on;
  gzip_min_length  1100;
  gzip_buffers     4 8k;
  gzip_types       text/plain text/html text/css text/js;
  # the server directive is nginx's virtual host directive.
  server {
    # port to listen on. Can also be set to an IP:PORT
    listen       80;
        # sets the domain[s] that this vhost server requests for
    #server_name  example.com www.example.com;
      # Set the max size for file uploads to 50Mb
    client_max_body_size 50M;
    # doc root
    root /Users/matt/code/examples/duck/public;
        # vhost specific access log
    access_log  logs/host.access.log  main;
    # If you have a 'maintenance.html' in your doc root, all
    # requests will be forwarded to that automatically.
    # This is part of Capistrano's 'disable_web' task.
    if (-f $document_root/maintenance.html){
      rewrite  ^(.*)$  /maintenance.html last;
      break;
    }

    location / {
      # needed to forward user's IP address to rails
      proxy_set_header  X-Real-IP  $remote_addr;
      # needed for HTTPS
      proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $http_host;
      proxy_redirect false;
      # Basic Caching
      # Add /index.html to the request and check to see if that
      # file exists. If it does, continue to the next config.
      if (-f $request_filename/index.html) {
        rewrite (.*) /index.html break;
      }
      # Rails Caching rules
      # Add .html to the end of the request, then check for a file
      # with that name. If the file exists, continue to the next 
      # config. Otherwise set the headers and proxy the request to
      # the mongrel cluster.
      if (-f $request_filename.html) {
        rewrite (.*) .html break;
      }
      if (! -f $request_filename) {
        proxy_pass http://mongrel;
        break;
      }
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   html;
    }
  }
}

You can test the configuration like so:

$ sudo /usr/local/sbin/nginx -t -c config/nginx.conf

Starting is the same as the testing command, without the -t option.

$ cd ~/code/examples/duck
$ sudo /usr/local/sbin/nginx -c config/nginx.conf

Stop using kill

$ kill -15 pid

4.3.2.3. Other Static Server Configurations

There are other Web server configurations and tools that will work well with Mongrel, including Pen, Pound, Litespeed, and others. You can find more details at the Mongrel Web site (http://mongrel. rubyforge .org).