Codex was right on all three, and the first was a design error on my part: the
checkout is bind-mounted into every container, so 'git merge' swaps the running
code instantly — 'migrations before traffic' was not achievable by ordering.
The updater now goes down → merge → dependencies → migrate → assets → restart →
up, trading a short deliberate outage for never serving code whose schema does
not exist yet. If a step fails the site STAYS down: coming back up with new code
on an old schema is worse than staying dark until someone looks.
It also records the last successfully deployed commit. A run that died halfway
left the checkout ahead, so the next run said 'already up to date' and skipped
the rest forever.
And it installs dependencies when a lockfile moved: vendor/ and node_modules/
live in the bind mount and shadow the image, so rebuilding the image never
updated them — migrations could run against stale packages.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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