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A few months ago I wrote quite popular :) manual how to install and use RoR, Capistrano and Mongrel with Apache on Gentoo. Things changed a little as the time goes and after some experiences with the nginx server on a Slicehost slice, I decided to write an updated manual and to use the nginx server instead of the Apache HTTP Server. Let’s start :)

A deployment process should be straightforward and automatic as much as possible. The main reason is that this process will be repeated many times and omitted or wrong steps usually cause hey-what-are-you-doing-the-site-does-not-work calls or e-mails from your customers. Fortunately, there is a nice tool for Ruby on Rails applications — Capistrano.

Now we know about a tool to automate the deployment of an application, but we need to deploy our application to a production environment — I decided for the combination of Mongrel and nginx.

…and everything runs on Gentoo :)

Here is my short howto:

Introduction

Let’s define CLIENT as a computer where you are developing an application, SERVER as a computer where you are going to deploy it and APP as the name of your application.
I assume that Gentoo is installed on both computers.

I decided to create a special user APP for the application on the server (if you do not like it, then all paths /home/APP replace with your favourite path ;).

I prefer the PostgreSQL database.

A short remark for copying text — if you would like to copy a text without any line numbers (they are fine for reading, but not for using on a command line or in a text file) click on the [Show Plain Code] link for each block of code or configuration file to display an unformatted text.

I. Client Software Installation

We will need to install Capistrano and Mongrel. (I assume that you already installed Ruby on Rails on your computer. :)

We need to unmask mongrel related packages – the mongrel_cluster is masked (29. August 2007) in the portage. Add the following lines to the /etc/portage/package.keywords file:

www-servers/mongrel_cluster
www-servers/mongrel
dev-ruby/fastthread

And install necessary software:

emerge capistrano mongrel mongrel_cluster

II. Server Software Installation

We will need to install Ruby, Ruby on Rails, Capistrano, Mongrel and nginx.

Add necessary use flags to the /etc/portage/package.use file, e.g.:

dev-ruby/rails postgres

to install a PostgreSQL support in RoR.

We need to unmask mongrel related packages, similarly as for the client side, add the following lines to the /etc/portage/package.keywords file:

www-servers/mongrel_cluster
www-servers/mongrel
dev-ruby/fastthread

and install all necessary software:

emerge rails capistrano app-admin/sudo mongrel_cluster nginx

(and maybe other dev-ruby/* packages that you used for your application). Sudo is needed for starting Mongrel.

III. Server Side Configuration

Let’s create a special user for the application (not necessary):

useradd -d /home/APP -m APP
passwd APP

Open the /etc/sudoers file and add the following line:

APP    ALL=(ALL) ALL

The main reason for creating a special user was a fact that the sudo command has to be available for a user. Frankly, I do not like the sudo command (sorry, Ubuntu guys). With su - it is clear when I have root privileges and when not (on Ubuntu I usually type sudo bash :).

I also created a new database user APP:

su -
su - postgres
createuser APP

and a new production database:

createdb -E utf-8 APP_production

IV. Client Side Configuration

Go to the application directory and create a configuration for Mongrel:

mongrel_rails cluster::configure -e production -p 8000 -a 127.0.0.1 -N 2 -c /home/APP/production/APP/current

it will create the config/mongrel_cluster.yml file; basically you do not need to edit it.

Then create a configuration for Capistrano (do not forget that APP is the name of your application):

cap --apply-to . APP

and in this case we need to modify the generated file config/deploy.rb — I added or changed the following lines:

require 'mongrel_cluster/recipes'

#you set the APP name with the cap command
set :application, "APP"
#a path to your repository
set :repository, "svn+ssh://USERNAME@SVN_SERVER/projects/#{application}/trunk"

role :web, "SERVER"
role :app, "SERVER"
role :db, "SERVER", :primary => true

#where to deploy (copy the files) on the server; I created a special user APP for the application (if you do not like it, replace the /home/#{application} part with your path
set :deploy_to, "/home/#{application}/production/#{application}"
set :mongrel_conf, "#{current_path}/config/mongrel_cluster.yml"
#if the server login name is different to the development computer login name; in my case the user name is the APP name
set :user, "APP"

It is also necessary to update the config/database.yml file:

#no changes needed, just to show the development configuration
development:
  adapter: postgresql
  database: APP_development
  username: ondrej
  host: 127.0.0.1
  encoding: unicode

#I changed the username to the database user name on the server
production:
  adapter: postgresql
  database: APP_production
  username: APP
  host: localhost
  encoding: unicode

Do not forget to add all new files and commit all changes (because Capistrano uses files in your repository).

V. Deployment

Create the basic structure on the server (files from the repository is not used in this step):

rake remote:setup

If there is something wrong: check the config/deploy.rb file; try to log to the server manually e.g. ssh APP@SERVER or ssh APP@SERVER -v -v -v; did you add and commit the config/deploy.rb file?

Let Capistrano do the magic :)

rake remote:cold_deploy

If there is something wrong: check the config/deploy.rb file; try to check out the repository manually on the server.

To check if everything went fine, access the http://SERVER:8000 link or the http://localhost:8000 link on the server. If you have a firewall, probably only the second option will work — you can use the console browser lynx or to be more professional ;) wget http://localhost:8000.

Anytime you can delete the /home/APP/production directory on the server and start from scratch. All files are safely stored in your repository. (Except the data in the database on the server.)

If you use migrations to create databases and to insert initial data (of course that you are! :), call the following command to run migrations on the server:

rake remote:migrate

For any next deployments use the following command:

rake remote:deploy

VI. nginx Configuration

Firstly define the following values:

• SERVER_IP is the IP address of your server, e.g. 1.2.3.4 ;)
• SERVER_NAME is the name of your server as it is specified in a DNS record for your SERVER_IP, e.g. company.com.
• APP.SERVER_NAME is a suggested value that would point to your application, e.g. application.company.com.

The (below) described configuration does the following:

• all http or https requests http://SERVER_NAME go to the standard web directory, by default to the /var/www/localhost/htdocs directory.
• http requests http://APP.SERVER_NAME go to your RoR application APP.

Log to the server as root (do you remember? su - :) and create or update (make a backup) the nginx configuration stored in the /etc/nginx/nginx.conf file:

user nginx nginx;
worker_processes 1;

error_log /var/log/nginx/error_log info;

events {
	worker_connections  8192;
	use epoll;
}

http {
	include		/etc/nginx/mime.types;
	default_type	application/octet-stream;

	log_format main
		'$remote_addr - $remote_user [$time_local] '
        	'"$request" $status $bytes_sent '
		'"$http_referer" "$http_user_agent" '
		'"$gzip_ratio"';
									       
	client_header_timeout	10m;
	client_body_timeout	10m;
	send_timeout		10m;

	connection_pool_size		256;
	client_header_buffer_size	1k;
	large_client_header_buffers	4 2k;
	request_pool_size		4k;

	gzip on;
	gzip_min_length	1100;
	gzip_buffers	4 8k;
	gzip_types	text/plain;

	output_buffers	1 32k;
	postpone_output	1460;

	sendfile	on;
	tcp_nopush	on;
	tcp_nodelay	on;

	keepalive_timeout	75 20;

	ignore_invalid_headers	on;

	index index.html;

	upstream mongrel {
		server 127.0.0.1:8000;
		server 127.0.0.1:8001;
	}

	server {
		listen		SERVER_IP;      # e.g. 1.2.3.4
		server_name	SERVER_NAME;    # e.g. www.company.com

		access_log	/var/log/nginx/localhost.access_log main;
		error_log	/var/log/nginx/localhost.error_log info;

		root /var/www/localhost/htdocs;
	}

	server {
		listen		SERVER_IP;              # e.g. 1.2.3.4
		server_name	APP.SERVER_NAME;        # e.g. application.company.com

		access_log	/var/log/nginx/localhost.access_log main;
		error_log	/var/log/nginx/localhost.error_log info;

		root /home/APP/production/APP/impl/public;

		location / {
			proxy_set_header  X-Real-IP  $remote_addr;
			proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
			proxy_set_header Host $http_host;
			proxy_redirect false;
			if (-f $request_filename/index.html) {
				rewrite (.*) $1/index.html break;
			}
			if (-f $request_filename.html) {
				rewrite (.*) $1.html break;
			}
			if (!-f $request_filename) {
				proxy_pass http://mongrel;
				break;
			}
		}
	}

	##ssl
	server {
		listen		SERVER_IP:443;  # e.g. 1.2.3.4:443
		server_name	SERVER_NAME;    # e.g. www.company.com
		
		ssl on;
		ssl_certificate		/etc/ssl/nginx/nginx.pem;
		ssl_certificate_key	/etc/ssl/nginx/nginx.key;
		
		access_log	/var/log/nginx/localhost.ssl_access_log main;
		error_log	/var/log/nginx/localhost.ssl_error_log info;
	
		root /var/www/localhost/htdocs;
	}
}

or simply download the nginx.cong file to your server.

Do not forget to replace SERVER_IP, SERVER_NAME and APP with your values :)

Restart the nginx server:

/etc/init.d/nginx restart

and test the http://APP.SERVER_NAME link — your application should appear :)

The http://SERVER_NAME link should display content stored in the standard web directory, by default the /var/www/localhost/htdocs directory. This could be an ideal place for your static pages and files.

Of course, do not forget to add the nginx service to the default runlevel to start it when the server starts:

rc-update add nginx default

To start the Mongrel instance I added the following line to the /etc/conf.d/local.start file:

mongrel_rails cluster::restart -C /home/APP/production/APP/current/config/mongrel_cluster.yml

and to stop it nicely, I added the following line to the /etc/conf.d/local.stop file:

mongrel_rails cluster::stop -C /home/APP/production/APP/current/config/mongrel_cluster.yml

You can stop server with the cluster::stop action and start with the cluster::start action.

Hopefully I helped you to configure your production environment.

Any comments are welcome…