Re: [BUGS] BUG #13793: Please implement IP_FREEBIND option

Christoph Berg <myon@debian.org> writes:
> http://man7.org/linux/man-pages/man7/ip.7.html

>        IP_FREEBIND (since Linux 2.4)
>               If enabled, this boolean option allows binding to an IP
>               address that is nonlocal or does not (yet) exist.  This per‐
>               mits listening on a socket, without requiring the underlying
>               network interface or the specified dynamic IP address to be up
>               at the time that the application is trying to bind to it.
>               This option is the per-socket equivalent of the ip_nonlo‐
>               cal_bind /proc interface described below.

> This had been requested in 2015 in bug #13793. I think it makes sense
> to support this. Especially with IPv6, it is very common that
> addresses are not yet assigned when services are starting. (I don't
> know yet if other OSes support this option as well.)

That man page says specifically that it's Linux-only, although that
shouldn't stop us from using it to solve a Linux-specific problem
(which systemd is, AFAIK).

> Do we want that in PostgreSQL?

IIRC, the main concern expressed previously is that this would completely
defeat error checking on the listen_addresses parameter.  However, that
doesn't apply if said parameter is "*".  Would there be any sense in
applying IP_FREEBIND only for "*"?

            regards, tom lane