heroku-last-deploy.rb

#!/usr/bin/env ruby

class Deploy
  def self.all(remote='staging')
    releases_txt = `heroku releases -r #{remote}`

    app_txt, *release_strs = releases_txt.split("\n")
    app, remote = app_txt[/===\s+(\S+)/, 1], remote

    deploy_strs = release_strs.select {|str| str =~ /^v\d+\s+Deploy/}
    deploys     = deploy_strs.map {|deploy_str| Deploy.new deploy_str, app, remote}

    deploys.reverse
  end

  #         version           SHA           time
  RE = %r{^(v\d+)\s+Deploy\s+(\h+)\s+\S+\s+(.+)}

  def initialize(deploy_str, app, remote)
    @app, @remote = app, remote
    _, @version, @sha, @time = *deploy_str.match(RE)
  end

  attr_reader :version, :sha, :time, :app, :remote

  def commit
    Git::Commit.new sha
  end

  def app_str
    "\napp #{app} (remote #{remote})\n\n"
  end
end

module Git
  class Commit
    def initialize(sha)
      @sha    =  sha
      @show   = `git show #{sha}`[%r{(.+)\n\ndiff}m, 1]
      @branch = `git branch --contains #{sha}`[%r{\* (.+)}, 1]
    end

    attr_reader :sha, :show, :branch

    def details
      "branch #{branch}\n#{show}\n\n\n"
    end
  end
end

remote  = ARGV[0] || 'staging'
deploys = Deploy.all remote

deploy  = deploys.last

puts deploy.app_str
puts deploy.commit.details