WebFaction Private Application Stack

The shell script webfaction.sh will automatically build and configure your own private Ruby on Rails stack. It was written with WebFaction users in mind, but is fairly generic. The directories $HOME/logs/user and $HOME/webapps/$APP_NAME are assumed to exist.

What's Provided

• git
• sqlite
• memcached (+ libevent)
• ruby (+ autoconf + openssl + libffi + yaml + gdbm) [tarball or subversion, see RUBY_SVN variable]
• rubygems: rack, rails, thin, unicorn, passenger, capistrano, sqlite3, mysql, pg, psych (commented out), memcache-client, memcached
• php (+ spawn-fcgi) [optional, see INSTALL_PHP variable]
• nginx (+ nginx-upstream-fair module [fair load balancing] + passenger module + pcre + zlib)
• monit
• couchdb (+ erlang + curl + icu4c + spidermonkey) [optional, see INSTALL_COUCHDB variable]
• startup scripts and working default configuration files for nginx and monit

Options

You have the choice of running with passenger or a thin cluster. Passenger is the default. You will have to follow a few extra steps to run thin. See below.

Before Running the Script

1. Create a rails app from the WebFaction control panel. Leave the autostart box unchecked.
2. Create an app of type "custom application (listing on port)" from the WebFaction control panel. Name it monit.
3. Assign values to the four variables at the beginning of the script: PREFIX, APP_NAME, APP_PORT, and MONIT_PORT.
   • PREFIX is the installation path prefix. It is the location of your "private application environment". It should be somewhere in your home directory. It has a default value of $HOME/apps. You could make it $HOME, but the home directory contains things that are better off separate. With a compartmentalized PREFIX like $HOME/apps, if you aren't happy with your setup, you could simply kill the application processes, execute rm -rf $HOME/apps and start over fresh.
   • APP_NAME is the name of the app created in step one. The path $HOME/webapps/$APP_NAME should exist and contain at least a skeleton app. The default value for APP_NAME is myrailsapp.
   • APP_PORT is the port WebFaction assigned to the app created in step one. The default value is 4000.
   • MONIT_PORT is the port WebFaction assigned to the app created in step two. The default value is 4002.
4. If you want to install ruby from the official subversion repository, edit line 12 of the script to read export RUBY_SVN=true
5. If you want to install php and spawnfcgi, edit line 13 of the script to read export INSTALL_PHP=true
6. If you want to install couchdb and erlang, edit line 14 of the script to read export INSTALL_COUCHDB=true

After Running the Script

If no errors occurred, your rails app will be up and running in the production environment. Of course, $HOME/webapps/$APP_NAME must contain a valid app for this to happen, even if it's just a skeleton.

By default, passenger serves the app. This can be easily changed so that two thin instances are set up listening on unix sockets with nginx as the fair load balancing reverse proxy. Monit watches nginx (and the thin servers, if set up). A crontab entry ensures that your setup springs back to life when the server is rebooted.

There are a couple of optional things you should do:

1. Inspect the nginx and monit conf files to learn how they work. Modify them as you like.
2. Generate ssl certificates and create an nginx https vhost following my example file if you have a dedicated IP address for https traffic.

Switching to thin

If you want to use thin instead of passenger:

Move the thin nginx vhost into place.

mv $PREFIX/etc/nginx/vhosts/$APP_NAME.conf $PREFIX/etc/nginx/vhosts/$APP_NAME-passenger.conf.example
mv $PREFIX/etc/nginx/vhosts/$APP_NAME-thin.conf.example $PREFIX/etc/nginx/vhosts/$APP_NAME.conf

Move the thin monitrc file into place.

mv $PREFIX/etc/monit/$APP_NAME.monitrc.example $PREFIX/etc/monit/$APP_NAME.monitrc

Reinitialize monit and restart all processes...

monit reload
monit restart all

To reclaim idle memory, you can prevent passenger processes from starting up with nginx. You have to manually edit $PREFIX/etc/nginx/nginx.conf. Comment out the passenger directives: passenger_root (most importantly), passenger_ruby, passenger_max_pool_size, and any others you add.

Also make sure that the upstream thin directive is uncommented in the nginx.conf file. I didn't comment it out to begin with because it doesn't do any harm.

psplus

Although the passenger stack uses less memory, the reported rss is probably higher. This is because of multiple counting. Depending on how WebFaction meters memory usage, this could be a practical downside.

To compare total rss with total private dirty rss (a better measure of actual memory usage) run these commands:

ps -u $USER -o rss | grep -v peruser | awk '{sum+=$1} END {printf("\n%.0fMB total RSS\n", sum/1024)}'
(ps -u $USER -o pid | awk '{ print "grep Private_Dirty /proc/"$1"/smaps" }' | sh | awk '{ sum += $2 } END { printf("%.0fMB total Private Dirty RSS\n\n", sum/1024) }') 2>/dev/null

You will see that your actual physical memory usage is much smaller than what rss reports. Use the psplus script included to display this. Move it into $PREFIX/bin and chmod 755 $PREFIX/bin/psplus.