On Mon, Jul 9, 2018, 9:00 PM Rich Felker, <dalias@libc.org> wrote:

> Can you provide a minimized test case (short single C source file) to
> reproduce this, or an strace log of the test that fails? The latter is
> probably actually be better if the behavior is dependent on the Docker
> network configuration. Assuming the test is attempting to lookup and
> bind on "localhost" by name, which is what it appears to be doing
> here:
>
>
> https://github.com/apache/thrift/blob/82ae9575cdc112088771fc7b876f75e1e4d85ebb/lib/cpp/test/TServerSocketTest.cpp
>
> the behavior you're experiencing is not what I expect from musl;
> rather my expectation is that you would get 127.0.0.1 as the first
> result and ::1 as the second, and this is exactly what I see if I do:
>
> ip addr del ::1 dev lo
>
> on my laptop running Alpine, then call getaddrinfo for localhost with
> a small test program.
>
> The logic to sort results does gratuitously depend on v4mapped
> addresses working to do the IPv4 routability probing; if something
> about the configuration suppresses their ability to work, it will
> break. This is a known open issue I want to go back and fix. Seeing
> the strace would show me right away if it's the source of your
> problem, and even if not chances are very good that it would point out
> whatever the cause is.
>

Strange - yeah, I'll write up a small program in C to demonstrate.

>