Monday, October 13, 2008

rake and vlad and mod_rails

I'm using Vlad to deploy my application, because it's so damn simple. Actually, I tried Capistrano, which also seemed pretty simple, until it just didn't work.

I'm not entirely sure why, and I didn't delve into the details, because a friend walked by and said "Capistrano? Really? All the Kool Kidz are using Vlad. Don't be a dork!". Actually, he said "life is too short to read documentation. Vlad only requires a couple of variables in your deploy.rb, and no capify. And it works."

The one thing I _do_ like about vlad is that it builds on top of rake, which means there is one less thing for me to keep track of.

Here are my notes about using Vlad with mod_rails:

(0) my deploy.rb contains the essentials:

set :application, "myapp"
set :domain, "machinename.foo.corp"
set :deploy_to, " /var/www/deploylocation"
set :repository, "http://svn/svn/proj_name/trunk/"
set :user, "arun"


(1) mod_rails detects restarts by scanning RAILS_ROOT/tmp/restart.txt. So a restart is super simple:
namespace :vlad do
remote_task :restart do
run "touch #{deploy_to}/current/tmp/restart.txt"
end
end


Note there is no vlad:restart, and when I had added this in, mod_rails support wasn't in mainline vlad.
(2) running remote tasks is insanely trivial:

remote_task :link_dirs do

run("ln -sf #{deploy_to}/data #{deploy_to}/current/public/data")

run("ln -sf #{deploy_to}/graphs #{deploy_to}/current/public/graphs")

run("ln -sf #{deploy_to}/current/doc #{deploy_to}/current/public/doc")
end

remote_task :chmod_cron do
run "chmod 4755 #{deploy_to}/current/sh/deploy_monitor.sh"
end


(3) sometimes, I've got to just run one of these. Usually, I've got to run all of them, in addition to the standard vlad update and migrate tasks. Rake specifies ordered dependencies like this:

task :full_vlad => ['vlad:update','vlad:migrate','vlad:link_dirs','vlad:chmod_cron','vlad:restart1']

Note the way that the vlad namespace is specified in the dependency array.

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