[openstack-dev] There is no Jenkins, only Zuul

James E. Blair corvus at inaugust.com
Thu Jun 16 22:41:14 UTC 2016

Since its inception, the OpenStack project has used Jenkins to perform
its testing and artifact building.  When OpenStack was two git repos,
we had one Jenkins master, a few slaves, and we configured all of our
jobs manually in the web interface.  It was easy for a new project
like OpenStack to set up and maintain.  Over the years, we have grown
significantly, with over 1,200 git repos and 8,000 jobs spread across
8 Jenkins masters and 800 dynamic slave nodes.  Long before we got to
this point, we could not manage all of those jobs by hand, so we wrote
Jenkins Job Builder[1], one of our more widely used projects, so that
we could automatically generate those 8,000 jobs from templated YAML.

We also wrote Zuul[2].

Zuul is a system to drive project automation.  It directs our testing,
running tens of thousands of jobs each day, responding to events from
our code review system and stacking potential changes to be tested

We are working on a new version of Zuul (version 3) with some major
changes: we want to make it easier to run jobs in multi-node
environments, easier to manage large numbers of jobs and job
variations, support in-tree job configuration, and the ability to define
jobs using Ansible[3].

With Zuul in charge of deciding which jobs to run, and when and where
to run them, we use very few advanced features of Jenkins at this
point.  While we are still working on Zuul v3, we are at a point where
we can start to use some of the work we have done already to switch to
running our jobs entirely with Zuul.

As of today, we have turned off our last Jenkins master and all of our
automation is being run by Zuul.  It's been a great ride, and
OpenStack wouldn't be where it is today without Jenkins.  Now we're
looking forward to focusing on Zuul v3 and exploring the full
potential of project automation.

[1] http://docs.openstack.org/infra/jenkins-job-builder/
[2] http://docs.openstack.org/infra/zuul/
[3] https://www.ansible.com/

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