Comment 11 for bug 2074017

Thank you Nobuto!

We have tried to reproduce the issue with PostgreSQL on MAAS setup using this manual:
https://charmhub.io/postgresql/docs/h-deploy-maas

We have successfully deployed rev429 to MAAS: https://pastebin.canonical.com/p/PjJM7fJYCZ/

From our experience, the Juju error message:
> ... failed to download charm "ch:amd64/jammy/postgresql-429" from API server: download request with archiveSha256 length 0 not valid
is just a noise and should be ignored.

JFYI, the difference between the legacy and modern postgresql charms is well described here:
https://charmhub.io/postgresql/docs/e-legacy-charm

TL;DR: Ractive VS Ops frameworks + Juju Secrets + Juju Storage in use for modern charm.
I suspect juju storage as the source of difference in experience between latest/stable (rev345) and 14/stable (rev429).

I recall the Juju limitations for nested virtualization and juju storage: https://bugs.launchpad.net/juju/+bug/2060098
and requirements for storage class definition on LXD levels: https://github.com/canonical/postgresql-operator/issues/354

In fact from the debug-log, juju didn't start the charm.py to pass execution to our code.
Juju stuck in a LXD/VM machine start.

Let's start with comparing the versions (see the bottom of) https://pastebin.canonical.com/p/PjJM7fJYCZ/
and trying to deploy one unit of Postgresql 14/stable (re 429) to your MAAS.
What do you think?