Deploying Rails Applications

© ThoughtWorks, 2006

Deploying Rails Applications

Vivek Prahlad

© ThoughtWorks, 2006 2

Agenda

Typical Rails deployment scenarios

Mongrel

Nginx vs. Apache vs. Lighttpd

Shared vs. Virtual vs. Dedicated hosting

Monitoring Rails Applications


Typical Rails Deployment Setup

Web Server(Static Content)

Rails App(Mongrel)

Database(MySQL / PostgreSQL)


Lots of Static content?


Rails App(Mongrel)

Database)

(MySQL / PostgreSQL)

Load

Bal

ance

r

Cluster


Heavy database load?


Rails App(Mongrel)


Cluster


Very dynamic application?


Rails App(Mongrel)


Cluster


Installing the stack using Deprec

cd /path/to/railsapp

deprec --apply-to . --name projectname --

domain www.projectname.com

# edit config/deploy.rb to add svn details

cap install_rails_stack

cap setup

cap deploy_with_migrations

cap restart_apache


Mongrel


Mongrel

Pure Ruby web server for Ruby applications

Supports Rails, Camping, Og + Nitro

Need a cluster due to Rails threadsafety issue

Significant footprint increase with Rails 1.2

• Approximately 60MB / Mongrel / Mephisto

instance

Dash B logging for detecting memory leaks



Nginx

Web server from Igor Sysoev: best used as a

reverse proxy

Rapidly becoming preferred choice of Rails

community

10MB footprint with 10,000 concurrent

connections

Load balancing

Weighted load balancing

Relatively straightforward configuration


Nginx vs. Apache

Apache: Relatively Larger footprint

Thread per request

Nginx: Low footprint

Non blocking IO


Issues with Lighttpd

Stability

Memory leaks

Non-trivial URL rewriting


Nginx: configuring mongrel

upstream mongrel {

server 127.0.0.1:10000;

server 127.0.0.1:10001;

}

proxy_pass http://mongrel;


Nginx: load balancing

upstream backend {

server backend1.example.com weight=5;

server backend2.example.com:8080;

server unix:/tmp/backend3;

}


Nginx: Caveats

Primary documentation in Russian

• (Documentation is rapidly improving,

though)

No X-sendfile support (useful for serving large

files)

Virtual host support poor


Rails Hosting

Rails 1.2+ unsuitable for shared hosting

Most shared hosts have published / unpublished

memory caps

• Textdrive: 47 MB per process

Dedicated hosting expensive

• Starts at ~ $70 per month (e.g.

ServerPronto)


Virtual Private Server (VPS) Hosting

Fits in between Shared and Dedicated hosting

Nice performance / price ratio (starts @ $20 /

month)

Can potentially exploit superior hardware

Alternatives:

• Xen

• Virtuzzo

Baked in kernel level virtualization support is

coming

Caveat: Need to manage your own setup


Advantages of VPS hosting

Entire CPU available when other users are idle.

Disk I/O usually faster than dedicated box (due

to RAID etc.)

Can take advantage of SANs if required.

Hosting company takes care of the VPS server

Fairly easy to scale VPS setup (just add more

VMs)


Monitoring Rails applications

Monit (http://www.tideslash.com/monit)

Process monitoring tool

Can monitor:

• HTTP server

• Processes

• Databases (MySQL and PostgreSQL)


Cron Jobs

Clear stale sessions

Database maintenance

Clear logs

Best practice: get Cron to call out to a script

Don't hardcode commands in the crontab

Makes it easy to test


Putting it all together

Can use Monit to create 'self healing' setup

PostgresQL

Nginx

Mongrel

Cron


http://nginx.net/

http://railsexpress.de/blog (performance tuning)

http://hostingfu.com (blog on hosting) http://www.slideshare.net/Georgio_1999/how-to-scale-your-web

-app/

(scaling Rails)

23

Additional Information


Thank You

http://blog.vivekprahlad.com/

Technology

Deploying Rails Applications