December 09, 2010

Deploying from your current branch with Capistrano

In some of the Rails projects I have worked on, I have found my self having to juggle multiple environments and often want to shuffle around which branch is deployed to which environment. I use Capistrano Multistage to handle all the different environments, but didn’t want to have to edit the deploy configuration every time I wanted to deploy. So I came up with a way to deploy from whatever my current local branch. Assuming this branch is on the remote git server, Capistrano would deploy from there.

In your config/deploy.rb file, add

# Bonus! Colors are pretty!
def red(str)
  "\e[31m#{str}\e[0m"
end

# Figure out the name of the current local branch
def current_git_branch
  branch = `git symbolic-ref HEAD 2> /dev/null`.strip.gsub(/^refs\/heads\//, '')
  puts "Deploying branch #{red branch}"
  branch
end

# Set the deploy branch to the current branch
set :branch, current_git_branch

The really cool thing about this is how intuitive it is to use. Goes something like this:

PM: Hey, can you deploy feature-x to staging! NOW! Me: K, git checkout feature-x && cap deploy staging

That just feels natural.

On other alternative was to setup a remote branch in git that matches each environment, and go a git reset --hard when you want to change things around. But with as often as we were redeploying that seemed burdensome.

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