The mesh generates a password, seals it to the machine that must accept
it, and discards the plaintext — so it cannot tell PostgreSQL to start
accepting it. Something on that machine reads what the host wrote and
makes it true. Everything up to that step is proven elsewhere; this is
where a password either becomes a login or does not.
A scenario with one machine and a database, and six assertions: the
password works, running again reaches the same state and says nothing,
rotation makes the new one work and the old one stop, a departed consumer
loses its login, a role nobody here made is left alone, and a manifest
naming a credential that was never written is refused rather than
creating a login with no password.
Each was confirmed to fail — and only it to fail — with the behaviour
removed from the provisioner: only-creates breaks rotation, no-revoke
breaks revocation, revoking everything breaks the bystander role, and
ignoring a missing credential breaks the refusal.
Two faults in the test itself, both worth recording:
- it checked logins from inside the database's own container over
127.0.0.1, which PostgreSQL's default pg_hba trusts. No password was
ever verified. Demonstrated directly: over loopback a deliberately
wrong password still returns a row. Only the rotation assertion
noticed, because it is the one that requires a password to STOP
working — which is an argument for writing that assertion every time.
- the fix then read .NetworkSettings.IPAddress, which docker 29 no
longer populates. It templates to empty, psql falls back to a unix
socket that is not there, and every login looks impossible rather than
misconfigured.
jschoubben
e89379fef8