Test Driven Devops

I like to apply Test Driven Development to my sysadmin work. For example, every time I add a new redirect to a web server configuration I want to make sure I haven’t broken anything else. Further, I want my SSL configurations proactively checked daily for any possible error. I use Ruby RSpec and write tests like these:

describe 'My app' do
  context 'www.myapp.com' do
    it { should be_up }
    it { should have_a_valid_cert }
  end

  it 'serves the www.myapp.com page without redirecting' do
    expect('http://www.myapp.com/about').to be_status 200
  end

  it 'only serves via www' do
    expect('http://myapp.com').to redirect_permanently_to 'http://www.myapp.com/'
  end

  it 'forces visitors to use https' do
  expect('myapp.com').to enforce_https_everywhere
  end
end

When I want to make a configuration change, I first write a test for the desired outcome. Naturally, it fails while the old tests pass. I then work on the config change, re-running all the tests as I go, and am finished when they all pass. I also run these automatically from a cron job to get pro-active notification of new problems.

The phrases such as have_a_valid_cert are custom RSpec matchers; they’re added into the RSpec environment by this open source library on Github.  I’m also working on an app to run these specs in the cloud.

See also

• Constant QA – Continuous web testing
• RSpec Custom Matchers: A Deep Dive
• Custom Matchers / RSpec Wiki