On 18-04-27 10:49:28, Stas Malyshev wrote:
Hi!
First, we now disallow multi-sync patch deployments. See T187761[0].
This means that the sync order of files is determined by git commit
parent relationships (or Gerrit's "depends-on"). This is to prevent SWAT
deployers from accidentally syncing two patches in the wrong order.
Question about this: if there's a patch that requires files to land in
specific order, e.g. one that part of the config is moved into another
file (example: https://gerrit.wikimedia.org/r/c/419367) is this handled
automatically by scap (i.e. all changes in the same patch land at the
same time atomically and scap takes care of nothing ever seeing the
intermediate states) or has to be managed manually, and if so, how?
Scap doesn't currently handle this since for MediaWiki deploys it's
still using rsync at a basic level.
Currently, syncing changes in a way that avoids bad intermediate states
is handled by the SWAT deployer and is determined on the fly at the time
of deployment.
That is, the deployer figures out how to sync stuff on the fly. And
deployers are pretty good at it, mostly. If I were deploying that change
today I'd split it up and sync one at a time:
- wmf-config/WikibaseSearchSettings.php
- wmf-config/InitialiseSettings.php
- wmf-config/Wikibase.php
- wmf-config/Wikibase-production.php
(or maybe I'd combine the last two into a sync-dir wmf-config).
The new policy asks the folks submitting patches to split up patches to
avoid bad intermediate states ahead of time.
So Instead of me syncing that change one file at a time, maybe that
change becomes two changes and I can pull a change that adds the
WikibaseSearchSettings.php file and the variables in
InitialiseSettings.php -- sync-dir wmf-config, and then a second patch
that could be synced all at once as well. Two syncs rather than 3 or 4
in this case.
The hope is that this will be more efficient, less error-prone, and
lower the difficulty factor for deployers. Ideally, this makes it more
and more difficult to earn a t-shirt[0] :)
-- Tyler
[0]. <https://photos.tylercipriani.com/i-broke-wikipedia.jpg>
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