Re: PG in container w/ pid namespace is init, process exits cause restart

On 2021-May-03, Tom Lane wrote:

> Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> writes:
> > I also heard a story where things ran into trouble (I didn't get the
> > whole story of *what* was the problem with that) because the datadir is /.
>
> BTW, as far as that goes, I think the general recommendation is that
> the datadir shouldn't be a mount point, because bad things happen if
> you mount or unmount the drive while the postmaster is up. I could
> see enforcing that, if we could find a reasonably platform-independent
> way to do it.

/ is not a mount point; it's just that the container system binds (?)
some different directory as / for the process to run into. I suppose it
must be similar to chrooting to /, but I'm not sure if it's exactly
that.

> (Of course, / can't be unmounted, so I wonder exactly what bad thing
> happened in that story.)

It's not related to unmounting. I'll try to get the details.

--
Álvaro Herrera Valdivia, Chile