Table of contents

Deploy an application to GOV.UK

Introduction

2nd line is responsible for:

  • ensuring that software is released to GOV.UK responsibly
  • providing access to deploy software for teams who can’t deploy it themselves

As far as possible, teams are responsible for deploying their own work. We believe that regular releases minimise the risk of major problems and improve recovery time.

If possible, you should avoid coupling multiple applications so that they all have to be deployed at once. Changes should be backwards compatible except in exceptional circumstances.

We have a staging environment that must always be deployed to immediately before production. Access to staging and production is restricted to certain people.

Release process

Only one release takes place at a time. One product team owns the release - if multiple teams are involved in the release, pick one.

Scheduling

Any member of the team responsible for a release can book a release slot. To book a release slot, find a free slot in the GOV.UK Release Calendar, then create an event in either your personal or your team’s calendar, including the “GOV.UK Release Calendar” as a guest.

Release slots are half an hour for normal changes and one hour for larger or more complex changes. The release calendar shows what times releases can happen - they can start from 9:30am and must be finished by 5pm, or 4pm on Fridays.

At an absolute minimum, you should include the name of the app or apps you’re deploying; you should probably also include a description of what you’re releasing and build numbers for all the apps. If you invite yourself to the event, people will be able to see who to talk to about it.

If you do not have deploy access, and you need someone from the 2nd line team to deploy for you, put as much information into the event as possible, include “2nd line required’ in the title. Please be considerate when booking deployments over lunchtime, the team need to eat too. If in doubt, ask.

The Badger

The Badger of Deploy stops multiple people deploying to GOV.UK at once. If you want to deploy to production, you must acquire the badger. You should display it prominently on your monitor, so people can see when you are deploying. Once your release is finished, return it to one of the people on 2nd line.

If the previous release is over-running slightly, you can technically deploy to staging without the badger. Be sensible, though: make sure before you start that the previous team isn’t going to have to roll back their release.

Deployment

  1. Check any notes against the application in the Release app.
  2. Acquire the badger
  3. Ensure the badger is not tagged with the application you are deploying, indicating that it is blocked from being released.
  4. Deploy to staging
  5. Check Smokey passes; remember most apps take a couple of minutes to restart
  6. Check the new functionality works as you would expect
  7. No, really: acquire the badger
  8. Deploy to production
  9. Check Smokey passes in production; once again, apps take a couple of minutes to restart
  10. Check the new functionality works in production
  11. Take a look at any alerts and metrics, just to check you haven’t broken something
  12. Return the badger to someone on 2nd line
  13. Stay around for a while just in case something goes wrong

Rollback

Make sure you have a rollback plan if things go wrong. When you’re just changing code, this is relatively easy; when you’re doing data migrations, less so. As far as is possible, all data migrations should be reversible. Don’t rely on backups unless you absolutely have to.

If a release fails on staging and you can fix it, test it in integration, redeploy it to staging, re-test it, deploy it to production and test it there, then that’s allowed. You’re probably better off rolling back and trying again later.

GitHub

We depend on both GitHub and GitHub Enterprise for deploying software to GOV.UK. We have processes in place to deploy if either of the GitHubs are unavailable.

Release application

The release app tracks releases.

You need to have a Signon account with appropriate permissions to access the release app.

On the blog

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