ERL-1383: Trouble configuring inet_db nameserver

[OTP-Maintainer]

Original reporter: JIRAUSER16901
Affected version: Not Specified
Component: Not Specified
Migrated from: https://bugs.erlang.org/browse/ERL-1383

---

* OTP version
 ** Erlang/OTP 24 [DEVELOPMENT] [erts-11.1.1] [source-820b2f696d] and Erlang/OTP 23 [erts-11.1.1]
 * Configure flags when building (e.g. ./configure --enable-halfword-emulator --enable-shared-zlib)
 ** KERL_CONFIGURE_OPTIONS="--disable-debug --disable-silent-rules --without-javac --enable-shared-zlib --enable-sctp --enable-smp-support --enable-threads --enable-kernel-poll --enable-wx --enable-darwin-64bit --with-ssl=/usr/local/opt/openssl@1.1"
 * Operating system/distribution
 ** MacOS 10.15.6

There appears to be a bug, which causes the order of configuration options in an erl_inetrc configuration file to be significant. I noticed this behaviour specifically with the `resolv_conf` and `nameserver` options, as described [here|[http://erlang.org/doc/apps/erts/inet_cfg.html].]For example, consider the following erl_inetrc file: 

 $ cat erl_inetrc
{nameserver, {1,1,1,1}}.

{resolv_conf, “”}.
 ```
 results in the following configuration:

 $ erl -kernel inetrc ‘“./erl_inetrc”’
Erlang/OTP 24 [DEVELOPMENT] [erts-11.1.1] [source-820b2f696d] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit]
Eshell V11.1.1 (abort with ^G)
1> inet:get_rc().
[\{domain,“local”},
 \{resolv_conf,[]},
 \{hosts_file,“/etc/hosts”},
 {lookup,[native]}]
 ```

However, if I switch the order of the nameserver & resolv_conf configuration, then it does load the nameserver as expected:```
$ cat erl_inetrc
\{resolv_conf, “”}.
\{nameserver, {1,1,1,1}}.

 $ erl -kernel inetrc ‘“./erl_inetrc”’
 Erlang/OTP 24 [DEVELOPMENT] [erts-11.1.1] [source-820b2f696d] [64-bit] [smp:16:16] [ds:16:16:10] [async-threads:1] [jit]
 Eshell V11.1.1 (abort with ^G)
 1> inet:get_rc().
 [\{domain,“local”},
  \{nameservers,{1,1,1,1}},
  \{resolv_conf,[]},
  \{hosts_file,“/etc/hosts”},
  {lookup,[native]}]

Just to be sure, I tried on the latest 23.1.1 release and confirmed the behaviour is the same there.

I have not noticed this issue with other configuration options, for example alt_nameserver works if it comes before or after the resolv_conf config.

Please excuse my formatting, I am fighting with this version of Jira...