5e668c952d
Much of this document was stale since putting Zuul v3 into production. Attempt to bring it up to our current state. Change-Id: I1b9d665cbf5ca88917d6e0361a6b16026b2ad6c6
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4.6 KiB
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140 lines
4.6 KiB
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:title: Zuul
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.. _zuul:
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Zuul
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####
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Zuul is a pipeline-oriented project gating system. It facilitates
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running tests and automated tasks in response to Gerrit events.
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At a Glance
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===========
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:Hosts:
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* https://zuul.openstack.org
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* ze*.openstack.org
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* zm*.openstack.org
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:Puppet:
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* https://git.openstack.org/cgit/openstack-infra/puppet-zuul/tree/
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* :cgit_file:`modules/openstack_project/manifests/zuul_prod.pp`
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* :cgit_file:`modules/openstack_project/manifests/zuul_dev.pp`
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:Configuration:
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* :config:`zuul/`
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* :config:`zuul.d/`
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:Projects:
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* https://git.zuul-ci.org/cgit/zuul
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:Bugs:
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* https://storyboard.openstack.org/#!/project/openstack-infra/zuul
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:Resources:
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* `Zuul Reference Manual <https://zuul-ci.org/docs/zuul>`_
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:Chat:
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* #zuul on freenode
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Overview
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========
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The OpenStack project uses a number of pipelines in Zuul, as defined
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in :config:`zuul.d/pipelines.yaml`.
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Zuul watches events in Gerrit (using the Gerrit "stream-events"
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command) and matches those events to the pipelines above. If a match
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is found, it adds the change to the pipeline and starts running
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related jobs.
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The **gate** pipeline uses speculative execution to improve
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throughput. Changes are tested in parallel under the assumption that
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changes ahead in the queue will merge. If they do not, Zuul will
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abort and restart tests without the affected changes. This means that
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many changes may be tested in parallel while continuing to assure that
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each commit is correctly tested.
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Zuul's current status may be viewed at
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`<https://zuul.openstack.org/>`_.
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Zuul's configuration is distributed across projects listed in
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:config:`zuul/main.yaml`. Anyone may propose a change to the
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configuration by editing configuration in those projects and submitting
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the change to Gerrit for review.
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For the full syntax of Zuul's configuration file format, see the `Zuul
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reference manual`_.
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Sysadmin
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========
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Zuul and gear are lightweight - it should be possible to run both on a
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1G instance for small deployments. OpenStack's deployment requires at
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least a 8G instance at the time of writing, though additional cache
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memory helps performance.
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Zuul is mostly stateless, so the server does not need backing up (though
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it does rely on a Trove instance for its build history). However zuul
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talks through git and ssh so you will need to manually check ssh host
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keys as the zuul user. e.g.::
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sudo su - zuul
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ssh -p 29418 review.openstack.org
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To debug Zuul's gearman server, SSL is required. Use the following
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command::
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openssl s_client -connect localhost:4730 -cert /etc/zuul/ssl/client.pem -key /etc/zuul/ssl/client.key
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Restarts
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--------
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Zuul restarts are disruptive, so non-emergency restarts should always be
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scheduled for quieter times of the day, week and cycle. To be as
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courteous to developers as possible, just prior to a restart the `Zuul
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Status Page <https://zuul.openstack.org/>`_ should be checked to
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see the status of the gate. If there is a series of changes nearly
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merged, wait until that has been completed.
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Since Zuul is stateless, some work needs to be done to save and then
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re-enqueue patches when restarts are done. To accomplish this, start by
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running `zuul-changes.py
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<https://git.zuul-ci.org/cgit/zuul/tree/tools/zuul-changes.py>`_
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to save the check and gate queues::
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python /opt/zuul/tools/zuul-changes.py http://zuul.openstack.org \
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check >check.sh
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python /opt/zuul/tools/zuul-changes.py http://zuul.openstack.org \
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gate >gate.sh
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These check.sh and gate.sh scripts will be used after the restart to
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re-enqueue the changes.
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Now use `service zuul-scheduler stop` to stop zuul and then run ps to
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make sure the process has actually stopped, it may take several seconds
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for it to finally go away.
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When you are satisfied that zuul is up, first run the gate.sh script and
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then check.sh to re-enqueue the changes from before the restart::
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./gate.sh
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./check.sh
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You may watch the `Zuul Status Page
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<https://zuul.openstack.org/>`_ to confirm that changes are
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returning to the queues. This frontend is provided by the zuul-web
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service on the same server, which may also need to be restarted.
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Executors
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---------
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Servers with names matching the pattern ze*.openstack.org are Zuul
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Executors. These are horizontally scalable components of Zuul which
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run Ansible within a Bubblewrap context and connect to job nodes.
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They can be started and stopped at will, and new ones added as
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necessary to accommodate load.
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Mergers
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-------
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Servers with names matching the pattern zm*.openstack.org are Zuul
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Mergers. These are horizontally scalable components of Zuul which
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perform git operations for the benefit of jobs. They can be started
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and stopped at will, and new ones added as necessary to accommodate
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load.
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