Jenkins is a Continuous Integration system that runs tests and automates some parts of project operations. It is controlled for the most part by Zuul which determines what jobs are run when.
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A large number and variety of jobs are defined in Jenkins. The configuration of all of those jobs is stored in git in the openstack-infra/config repository. They are defined in YAML files that are read by Jenkins Job Builder which configures the actual jobs in Jenkins.
Anyone may submit a change to the openstack-infra/config repository that defines a new job or alters an existing job by editing the appropriate YAML files. See Jenkins Job Builder for more information.
Because of the large number of builds that Jenkins executes, the OpenStack project favors the following approach in configuring Jenkins jobs:
- Minimal use of plugins: the more post-processing work that Jenkins needs to perform on a job, the more likely we are to run into compatibility problems among plugins, and contention for shared resources on the Jenkins master. A number of popuplar plugins will cause all builds of a job to be serialized even if the jobs otherwise run in parallel.
- Minimal build history: Jenkins stores build history in individual XML files on disk, and accessing a large build history can cause the Jenkins master to be unresponsive for a significant time while loading them. It also increases memory usage. Instead, we generally keep no more than a day’s worth of builds.
- Move artifacts off of Jenkins: Jenkins is not efficient at serving static information such as build artifacts (e.g., tarballs) or logs. Instead, we copy them to a static webserver which is far more efficient.
Jenkins is set up to use OpenID in a Single Sign On mode with Launchpad. This means that all of the user and group information is managed via Launchpad users and teams. In the Jenkins Security Matrix, a Launchpad team name can be specified and any members of that team will be granted those permissions. However, because of the way the information is processed, a user will need to re-log in upon changing either team membership on Launchpad, or changing that team’s authorization in Jenkins for the new privileges to take effect.
OpenStack integration testing is performed by the devstack gate test framework. This framework runs the devstack exercises and Tempest smoketests against a devstack install on single use cloud servers. The devstack gate source can be found on Github and the Readme describes the process of using devstack gate to run your own devstack based tests.
The Devstack Gate project is used to maintain a pool of Jenkins slaves that are used to run these tests. Devstack-gate jobs create and delete Jenkins slaves as needed in order to maintain the pool.