[erlang-questions] Inet config - don't monitor config files

[Peti Gömöri]

Hi all,

We are not using native DNS lookup but Erlang's own implementation. We
would like to read config files at startup but we don't want inet to
monitor them for changes.

I was happy to find in the documentation an example that does just
that for the hosts file (
http://www.erlang.org/doc/apps/erts/inet_cfg.html#id86806 )

%% -- ERLANG INET CONFIGURATION FILE --
      %% read the hosts file
      {file, hosts, "/etc/hosts"}.
      %% do not monitor the hosts file
      {hosts_file, ""}.

Great, this works fine so I tried the same for resolv.conf:

      %% read nameserver config from the resolv.conf file
      {file, resolv, "/etc/resolv.conf"}.
      %% do not monitor the resolv.conf file
      {resolv_conf, ""}.

Unfortunately this does not work for resolv.conf because inet_config
will remove all previous nameserver entries upon processing the
{resolv_conf, _} parameter and it always processes the {file, _, _}
parameters first (so reordering the config file does not help either).
Actually there is also problem if I don't specify any resolv_conf
option. Although the default resolv.conf won't be read at startup
(because of this commit
https://github.com/erlang/otp/commit/0377ecdfb001c4dc1b507ebc06211f29b19048e3)
but it will be at the first name lookup and it will remove previous
entries too.
See attached logs with empty and default resolv_conf settings respectively.

(Using R16B03-1 but there were hardly any changes on the relevant files since.)

So I don't see any way how {file, resolv, _} option could have any effect.
Is this intentional or a bug? How should the desired goal be achieved?

If this is a bug I would be happy to create a patch with some guidance
- should the empty string be special cased to not clear the previous config?


thanks
Peter
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