Hi!
On Tue, Mar 23, 2021 at 2:59 PM Kunal Mehta <legoktm(a)member.fsf.org> wrote:
As with all
things, some exceptions may apply. The Release Engineering
team has created some guidelines[0] that will hopefully help explain
when something MUST, SHOULD, or MAY[1] be deployed via the train or via
backport.
Is this suppose to codify existing practice, or suggest/recommend people
should be deploying things more frequently outside of the normal train?
Tgr has raised roughly the same question on the talk page:
<https://wikitech.wikimedia.org/wiki/Talk:Deployments/Train_vs_backport>.
Arg! Missed that there was discussion there :(
I'll follow-up here and try to answer the additional questions there as
well.
The intent of this page is to encourage more deployments outside of the
normal train by developers and code authors.
This page was meant to make clear the types of changes that would be
difficult to deploy outside of the train for historical reasons, and to
encourage the authors of other types of patches to consider deploying the
change themselves or with a deployer in a backport window.
There are a few reasons that releng wants to encourage backports:
1. Smaller deployments are easier to reason about
2. The code author is often in the best position to reason the effect of
their changes
3. The use of mwdebug as a manual testing platform, while similar to the
group-by-group rollout of the train, can ensure that a change is working on
several wikis in multiple groups with no impact to users.
Not every patch can be backported (just due to hours/day -- 420 changes
this train[0] -- 5 minute deploy each is 35 hours of deploying), also
backport windows are finite, and deployers time is limited. With those
constraints in mind, we'd still like to move to a more continuous model of
delivery and the hope is that these guidelines are a step in that
direction. I'm also open to other ideas about ways to make the train a
lighter and more consistent process.
Thanks!
-- Tyler
[0]: <https://www.mediawiki.org/wiki/MediaWiki_1.36/wmf.36/Changelog>