openstack/tempest
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1c5f341c41
tempest/doc/source/requirement_upper_constraint_for_tempest.rst
Ghanshyam Mann d89122be41 Document the process to pin the constraint in tox.ini 
As discussed in Victoria PTG[1], we need to start pining
the constraint in tox.ini on Tempest new release so that our
tox.ini can match with compatible constraints with Tempest version.

[1] https://etherpad.opendev.org/p/qa-victoria-ptg

Change-Id: Ib705f59ef3aea93b2778cc87fc44d390b5a62c94
2020-07-07 13:11:42 +00:00

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Requirements Upper Constraint for Tempest

Tempest is branchless and supported stable branches use Tempest master and all EM stable branches use old compatible Tempest version for their testing. This means the OpenStack installed upper-constraints might not be compatible with Tempest used for stable branch testing. For example, if Tempest master is used for testing the stable/stein then stable/stein constraint might not be compatible with Tempest master so we need to use master upper-constraints there. That is why we use virtual env for Tempest installation and running tests so that we can control Tempest required constraint from system wide installed constraints.

Devstack takes care of using the master upper-constraints when Tempest master is used. But when old Tempest is used then devstack alone cannot handle the compatible constraints because Tempest in-tree tox.ini also set the upper-constraints which are master constraints so if devstack set the different constraints than what we have in tox.ini we end up re-creation of venv which flush all previously installed tempest plugins in that venv. More details are on this ML thread

To solve that problem we have two ways:

  1. Set UPPER_CONSTRAINTS_FILE to compatible constraint path This option is not easy as it requires to set this env var everywhere Tempest tox env is used like in devstack, grenade, projects side, zuulv3 roles etc.
  2. Pin upper-constraints in tox.ini If we can pin the upper-constraints in tox.ini on every release with the branch constraint at the time of release then we can solve it in an easy way because tox can use the compatible constraint at the time of venv creation itself. But this can again mismatch with the devstack set constraint so we need to follow the below process to make it work.

How to pin upper-constraints in tox.ini

This has to be done exactly before we cut the Tempest new major version bump release for the cycle.

Step1: Add the pin constraint proposal in QA office hour.

Pin constraint proposal includes:

Step2: Approve pin constraint and its revert patch together.

During office hour we need to check that there are no open patches for Tempest release and accordingly we fast approve the 'pin constraint' and its revert patch during office hour itself. Remember 'pin constraint patch' has to be the last commit to include in Tempest release.

Step3: Use 'pin constraint patch' hash for the Tempest new release.

By using the 'pin constraint patch' hash we make sure tox.ini in Tempest released tag has the compatible stable constraint not the master one. For Example Tempest 24.0.0