Re: [PATCH] Reload SSL certificates on SIGHUP

On 5/30/15 10:14 PM, Andreas Karlsson wrote:
> I have written a patch which makes it possible to change SSL
> certificates (and other SSL parameters, including the CRL) without
> restarting PostgreSQL. In fact this patch also makes it possible to turn
> on or off ssl entirely without restart. It does so by initializing a new
> SSL context when the postmaster receives a SIGHUP, and if the
> initialization succeeded the old context is replaced by the new.

I think this would be a useful feature, and the implementation looks
sound.  But I don't like how the reload is organized.  Reinitializing
the context in the sighup handler, aside from questions about how much
work one should do in a signal handler, would cause SSL reinitialization
for unrelated reloads.  We have the GUC assign hook mechanism for
handling this sort of thing.  The trick would be that when multiple
SSL-related settings change, you only want to do one reinitialization.
You could either have the different assign hooks communicate with each
other somehow, or have them set a "need SSL init" flag that is checked
somewhere else.

> There was some previous discussion[1] on the mailing list about what the
> proper context should be for the SSL parameters, but as far as I can
> tell the discussion never reached a conclusion. I have changed the SSL
> GUCs to PGC_SIGUP since I felt that was the closest to the truth, but it
> is not a perfect fit (the backends wont reload the SSL context). Should
> we add a new context for the SSL GUCs?

I think PGC_SIGHUP is fine for this.