Rake task for precompiling assets locally before deploying to Heroku

deploy.rake

require 'fileutils'

# Warning: The following deploy task will completely overwrite whatever is currently deployed to Heroku.
# The deploy branch is rebased onto master, so the push needs to be forced.

desc "Deploy app to Heroku after precompiling assets"
task :deploy do
  deploy_branch   = 'heroku'
  remote          = 'heroku'
  deploy_repo_dir = "tmp/heroku_deploy"

  begin
    # Check branch and working directory. Fail if not on clean master branch.
    branch = `branch_name=$(git symbolic-ref HEAD 2>/dev/null); branch_name=${branch_name##refs/heads/}; echo ${branch_name:-HEAD}`.strip
    if branch != 'master'
      raise "You have checked out the #{branch} branch, please only deploy from the master branch!"
    end
    if `git status --porcelain`.present?
      raise "You have unstaged or uncommitted changes! Please only deploy from a clean working directory!"
    end

    unless File.exists? deploy_repo_dir
      # Copy repo to tmp dir so we can continue working while it deploys
      @new_repo = true
      puts "Copying repo to #{deploy_repo_dir}..."
      # Can't copy into self, so copy to /tmp first
      FileUtils.cp_r Rails.root.to_s, "/tmp/heroku_deploy"
      FileUtils.mv "/tmp/heroku_deploy", Rails.root.join('tmp')
    end

    # Change working directory to copied repo
    Dir.chdir(deploy_repo_dir)

    # Create new deploy branch if starting with a fresh repo
    if @new_repo
      # Set remote to parent git dir, so we can fetch updates on future deploys
      system "git remote set-url origin ../.."
      system "git checkout -b #{deploy_branch}"

      # Allow git to see public/assets
      puts "Removing public/assets from .gitignore..."
      system 'sed -i '' "/^[\/?]public\/assets/d" .gitignore'
      system 'git add .gitignore; git commit -m "Allow git to commit public/assets"'
    else
      # Otherwise, we're already on the deploy branch, so fetch any new changes from original repo
      system "git fetch origin"

      # Rebase onto origin/master.
      # This step should never fail, because we are rebasing commits for files
      # that should be ignored by the master repo.
      unless system "git rebase origin/master"
        raise "Rebase Failed! Please delete tmp/heroku_deploy and start again."
      end
    end

    # Precompile assets
    Rake::Task['assets:precompile'].invoke

    # Add any extra tasks you want to run here, such as compiling static pages, etc.


    # Add all changes and new files
    system 'git add -A'

    commit_message = "Added precompiled assets"

    if @new_repo
      # Create new commit for new repo
      system "git commit -m '#{commit_message}'", :out => "/dev/null"
    else
      # If existing repo, amend previous assets commit
      system "git commit --amend -m '#{commit_message}'", :out => "/dev/null"
    end
    puts "Commit: #{commit_message}"


    # Force push deploy branch to Heroku
    puts "Pushing #{deploy_branch} branch to master on #{remote}..."
    IO.popen("git push #{remote} #{deploy_branch}:master -f") do |io|
      while (line = io.gets) do
        puts line
      end
    end
  end
end

I used it with a small change. Rather than origin, I used #{remote} in shell commands because I don't use a separate origin repo, just the Heroku repo.

bash and sh will both use their built-in echo. bash's echo supports the -n flag, but sh does not

 ➔ sh
sh-3.2$ type cho
sh: type: cho: not found
sh-3.2$ type echo
echo is a shell builtin
sh-3.2$ /bin/echo foo
foo
sh-3.2$ echo foo
foo
sh-3.2$ /bin/echo -n foo
foosh-3.echo -n foo
-n foo

(ignore type cho)

@ndbroadbent why not make this rake task a part of the turbo-sprockets-rails3 gem?

great work man! I've a bad case of premature heroku deploying without the assets:precompile - this works great. Love the gem also, well done.

Thanks for this! One suggestion, change the FileUtils.cp_r on line 27 to using the system command:

system "cp -r #{Rails.root} /tmp/heroku_deploy"

I had a socket file in my tmp/ and FileUtils.cp_r() failed with the following error. Only cp -r told me which file.

$ rake deploy
Copying repo to tmp/heroku_deploy...
rake aborted!
cannot handle socket
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:1357:in `copy'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:465:in `block in copy_entry'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:1433:in `preorder_traverse'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:462:in `copy_entry'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:437:in `block in cp_r'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:1515:in `block in fu_each_src_dest'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:1531:in `fu_each_src_dest0'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:1513:in `fu_each_src_dest'
/Users/turadg/.rbenv/versions/1.9.3-p327-perf/lib/ruby/1.9.1/fileutils.rb:436:in `cp_r'

👍 @turadg I also had a socket this barfed on.

The sed command didn't work for me, probably because I'm on zsh. Removing the brackets helped: sed -i "" "/^public\/assets/d" .gitignore