tempest/doc/source/stable_branch_support_policy.rst

Stable Branch Support Policy

Since the Extended Maintenance policy for stable branches was adopted OpenStack projects will keep stable branches around after a "stable" or "maintained" period for a phase of indeterminate length called "Extended Maintenance". Prior to this resolution Tempest supported all stable branches which were supported upstream. This policy does not scale under the new model as Tempest would be responsible for gating proposed changes against an ever increasing number of branches. Therefore due to resource constraints, Tempest will only provide support for branches in the "Maintained" phase from the documented Support Phases. When a branch moves from the Maintained to the Extended Maintenance phase, Tempest will tag the removal of support for that branch as it has in the past when a branch goes end of life.

The expectation for Extended Maintenance phase branches is that they will continue running Tempest during that phase of support. Since the REST APIs are stable interfaces across release boundaries, branches in these phases should run Tempest from master as long as possible. But, because we won't be actively testing branches in these phases, it's possible that we'll introduce changes to Tempest on master which will break support on Extended Maintenance phase branches. When this happens the expectation for those branches is to either switch to running Tempest from a tag with support for the branch, or exclude a newly introduced test (if that is the cause of the issue). Tempest will not be creating stable branches to support Extended Maintenance phase branches, as the burden is on the Extended Maintenance phase branch maintainers, not the Tempest project, to support that branch.