Continous Delivery with Drone and Dokku

2014-05-10 − 🏷 docker 🏷 drone 🏷 devops 🏷 testing

A part of my job as CTO of Output is managing our deployment and production systems. To this end, I’ve spent a lot of time working with virtualization, Docker and automation recently. I’ll try to share some of our experiences here in the months to come. One of our biggest challenges has been to get a good testing culture internally. To that end, I wanted a solid solution for CI.

This seems like a solved problem. Just fire up Jenkins, and you’re done. However, there are always complications. Hard to install dependencies, Selenium tests, required infrastructure services. That is why I have grown to love Drone. Run your test suite in a clean docker image every time, cache your dependencies (just like Heroku does), and run a deploy action of your choice if the test succed. Drone also supports various notification mechanisms, including Email (of course), IM and our favorite Slack.

It also has support for a host of linked services, including PostgreSQL, MySQL, MongoDB and Redis, but writing your own is also easy if needed. I’ve added support to Beanstalkd for us, and plan to contribute this back soon.

To make this even sweeter, I’ve coupled Drone with Dokku, a simple Heroku like PAAS built on top of Docker. We follow the Github flow, and this setup allows us to automatically stage all feature branches that pass their tests.

Installing dokku and drone is simple enough, and well documented in their respective projects, so I won’t cover that here. However, here is the .drone.yml config we use in the Output web backend repository:

image: bradrydzewski/ruby:2.1.1 
  - /tmp/bundler
  - DATABASE_URL=postgres://[email protected]/input_test 
  - RACK_ENV=test
  - DISPLAY=:10
  - postgres
  - nordaaker/beanstalkd
    team: nordaaker
    token: [redacted]
    channel: '#io'
    username: drone
    on_started: true
    on_success: true
    on_failure: true
  - mkdir -p /tmp/bundler
  - sudo chown ubuntu:ubuntu /tmp/bundler
  - bundle install --path=/tmp/bundler
  - bundle
  - createdb input_test -E UTF8 -T template0 -U postgres -h localhost
  - bundle exec rake db:
  - Xvfb :10 -ac &
  - firefox &
  - bundle exec rake test
      - 'perl'

Let’s go through it quickly; The backend is built on Padrino, and we run it using the most recent ruby image. The cache setting is to avoid having to reinstall all the rubygems on every test run, and then we setup ENV for the Database connection as well as setting padrino in test mode, and the X11 display for integration tests.

Then we configure two services to be used; the built in postgres service, and the beanstalkd service we built. We also set up notifications for every event to the excellent Slack.

Next comes the test script. These are just run in sequence we setup bundler with the cache, create the database, run migrations and then start up the virtual X11 server. Finally we run the actual tests.

If they succeed, the deploy script is run. Drone supports many deploy scenarios out of the box, but to get what I wanted, I wrote this little Perl script:

#!/usr/bin/env perl
system('git config --global $(git --no-pager log -1 --pretty=format:\'%an\')') == 0 || die 'Could not set name';
system('git config --global $(git --no-pager log -1 --pretty=format:\'%ae\')') == 0|| die 'Could not set email';
my $branch=$ENV{DRONE_BRANCH};
die "No branch" unless $branch;
print 'Deploying to [email protected]:'.  ( $branch eq 'master' ? 'input' : 'input-'.$branch ) ."\n";
system('git remote add deploy [email protected]:'. 
  ( $branch eq 'master' ? 'input' : 'input-'.$branch )) == 0 || die 'Could not add target';
system('git push deploy +'.$ENV{DRONE_BRANCH}.':master') == 0 or die 'Unable to push to remote';

It sets up the git environment, normalizes the current branch name, then pushes to dokku, which either creates or updates an app based on the repo name we push to, and deploys it. Once it’s done, we get a success message in Slack.