Re: Patch proposal: make use of regular expressions for the username in pg_hba.conf

On Fri, Aug 19, 2022 at 1:13 AM Drouvot, Bertrand <bdrouvot(at)amazon(dot)com> wrote:
> This is why I think username filtering with regular expressions would
> provide its own advantages.
>
> Thoughts? Looking forward to your feedback,

I think your motivation for the feature is solid. It is killing me a
bit that this is making it easier to switch authentication methods
based on the role name, when I suspect what someone might really want
is to switch authentication methods based on the ID the user is trying
to authenticate with. But that's not your fault or problem to fix,
because the startup packet doesn't currently have that information.
(It does make me wonder whether I withdrew my PGAUTHUSER proposal [1]
a month too early. And man, do I wish that pg_ident and pg_hba were
one file.)

I think you're going to have to address backwards compatibility
concerns. Today, I can create a role named "/a", and I can put that
into the HBA without quoting it. I'd be unamused if, after an upgrade,
my rule suddenly matched any role name containing an 'a'.

Speaking of partial matches, should this feature allow them? Maybe
rules should have to match the entire username instead, and sidestep
the inevitable "I forgot to anchor my regex" problems?

Thanks,
--Jacob

[1] https://commitfest.postgresql.org/38/3314/