proxy_pass behavior

[Maxim Dounin]

Hello!

On Thu, Mar 27, 2014 at 01:12:18PM -0400, Jim Popovitch wrote:

> On Thu, Mar 27, 2014 at 12:59 PM, Maxim Dounin <mdounin at mdounin.ru> wrote:
> > Hello!
> >
> > On Thu, Mar 27, 2014 at 12:29:03PM -0400, Jim Popovitch wrote:
> >
> >> Should proxy_pass retry ipv4 if ipv6 fails?   Currently (1.5.12), it
> >> does not, and there is no way to force proxy_pass to always use ipv4.
> >
> > In no particular order:
> >
> > - The proxy_next_upstream is expected to retry by default.
> 
> Yes, that works if the host name has 2 or more A  OR  2 or more AAAA
> records.  proxy_next_upstream does not appear to transition to the
> next protocol (i.e. from ipv4 to ipv6)

It doesn't care about address family.  As long as connect() to 
one address fails, it will try next one.

> > - There _is_ a way to force proxy_pass to always use ipv4 - you
> >   should configure your system accordingly, and
> >   getaddrinfo(AI_ADDRCONFIG) as used by nginx will do the right
> >   thing.  E.g., on Linux net.ipv6.conf.all.disable_ipv6 can be set
> >   to disable use of ipv6.
> 
> :-)  That's unacceptable!!  :-)   I don't want people to disable ipv6,
> I want proxy_pass to use ipv6 and upon failure use ipv4.  ;-)

It was you who claimed that "there is no way to force proxy_pass 
to always use ipv4".  There is.

-- 
Maxim Dounin
http://nginx.org/