Stop Merging Broken Code: An Introduction to Zuul

Being one of the biggest open source projects with hundreds of code repositories and tens of thousands of commits with each release, OpenStack's CI faces unprecedented scale problems. Among those chal …

Being one of the biggest open source projects with hundreds of code repositories and tens of thousands of commits with each release, OpenStack’s CI faces unprecedented scale problems. Among those challenges, making sure that the code base is always healthy is the most critical one; but conventional CI workflows cannot keep up with the velocity of OpenStack’s contributors as a whole.New problems require new solutions, and thus the OpenStack community came up with Zuul, the “Gate Keeper” ( https://zuul-ci.org ). Zuul is a code gating system that drives CI/CD workflows. At version 3, it is flexible enough to be used with projects of any scale to ensure code sanity.This presentation aims to introduce Zuul’s core concepts like “code gating”, ie automate merging changes to projects only if their tests pass; and “speculative merging”, ie “testing the future” to detect problems early. Zuul’s main features will also be discussed. Finally, pointers will be given to deploy and test Zuul.