I ended up writing this snippet after I found out that deploying a git branch with vlad wasn’t as easy as it should’ve been…

I assumed the Vlad documentation was right, so I put the branch name in the revision variable (located in config/deploy.rb):

   1  set :revision,              'branch_name'

But then I got this error when executing rake vlad:deploy:

   1  git checkout: updating paths is incompatible with switching branches/forcing
   2  Did you intend to checkout 'branch_name' which can not be resolved as commit?

I managed to solve the problem by using the SHA1 hash of the branch instead of the branch name, but that only worked for the current revision:

   1  set :revision,              'd34360870be6536992e6d45bb0aa72eca31e14443'

So after some googling I found this post at scie.nti.st, which made my day because it has the following examples of how to deploy tags and branches with git and Vlad:

   1  # Deploy the latest code, this the default
   2  set :revision, "HEAD" 
   3  
   4  # Deploy branch "origin/branch_name"
   5  set :revision, "origin/branch_name"
   6   
   7  # Deploy tag "1.0"
   8  set :revision, "1.0"

Note that you have to push the branch to the remote server before running rake vlad:deploy:

   1  git push origin branch_name

This is a draft…

Installing Vlad the Deployer

   1  gem install vlad

Configuring Vlad the Deployer

Add this to the end of RakeFile:

   1  begin
   2    require 'rubygems'
   3    require 'vlad'
   4    Vlad.load :scm => :git
   5  rescue LoadError => e
   6    puts "Unable to load Vlad #{e}."
   7  end

Note that we’re telling Vlad to use git. This snippet- gives you a quick introduction on how to use git with Rails.

Creating the deployment recipe

If you’re uncertain what these variables mean, have a look at the docs. This folder is also worth a look, and don’t forget to take a peek at the vlad source code.

   1  #
   2  # General configuration
   3  #
   4  set :ssh_flags,             '-p 666'
   5  set :application,           'xxx.com'
   6  set :domain,                '127.0.01'
   7  set :deploy_to,             '/var/www/xxx.com'
   8  set :repository,            '/var/lib/git/repositories/xxx.com/.git/'
   9  
  10  
  11  #
  12  # Mongrel configuration
  13  #
  14  set :mongrel_clean,         true
  15  set :mongrel_command,       'sudo mongrel_rails'
  16  set :mongrel_group,         'www-data'
  17  set :mongrel_port,          9000
  18  set :mongrel_servers,       3
  19  
  20  #set :mongrel_address,       '127.0.0.1'
  21  #set(:mongrel_conf)          { '#{shared_path}/mongrel_cluster.conf' }
  22  #set :mongrel_config_script, nil
  23  #set :mongrel_environment,   'production'
  24  #set :mongrel_log_file,      nil
  25  #set :mongrel_pid_file,      nil
  26  #set :mongrel_prefix,        nil
  27  #set :mongrel_user,          'mongrel'
  28  
  29  #
  30  # Customize Vlad to our needs
  31  #
  32  namespace :vlad do
  33    #
  34    # Add an after_update hook
  35    #
  36    remote_task :update do
  37      Rake::Task['vlad:after_update'].invoke
  38    end
  39  
  40    #
  41    # The after_update hook, which is run after vlad:update
  42    #
  43    remote_task :after_update do
  44    # Link to shared resources, if you have them in .gitignore
  45    #  run "ln -s #{deploy_to}/shared/system/database.yml #{deploy_to}/current/config/database.yml"
  46    end
  47  
  48    #
  49    # Deploys a new version of your application
  50    #
  51    remote_task :deploy => [:update, :migrate, :start_app]
  52  end

Setup the server

   1  $ rake vlad:setup

This will create the necessary folders and mongrel_cluster configuration file.

Deploy the application

Now deploy the application with vlad:deploy, which is a custom rake task that we added to the deployment recipe:

   1  $ rake vlad:deploy

Copying your SSH public key to the remote server

Vlad uses ssh for executing commands on the remotely, and rsync for copying the build to your server, which means you’ll quickly grow tired of typing your password each time a command is run.

This problem is solved by copying your public SSH keys to the remote server, this snippet- explains how to do exactly that.