Add nsswitch.conf to Minecraft docker image to fix localhost resolution

[notgne2]

There is the related issue here golang/go#22846

rcon-cli uses Go, which will resolve localhost incorrectly on certain machines, this could be fixed by creating a basic nsswitch.conf, echo 'hosts: files dns' > /etc/nsswitch.conf should do

[itzg]

Is there a particular way you are running the docker container or the daemon that causes that issue for you? I have never encountered localhost not resolving within the container.

[notgne2]

I think it may depend on the actual network configuration of the network the host machine uses, as unless I am missing something, this issue results in the go DNS resolving skipping resolution using /etc/hosts.

It has had issues on 4 out of 5 CentOS 7 hosts I have tried it on, with identical docker configurations, and have been working around in the meantime by adding GODEBUG=netdns=cgo to env.

[itzg]

I'll work on adding this change sometime today, but I'll need you to verify the fix since I am not able to recreate it and have heard no other reports of this. I was quite confident the addition of nsswitch.conf will fix it; however, this comment of the issue worries me since the minecraft server image is based on Alpine.

[itzg]

This change has been pushed to Docker Hub. @notgne2 , can you see if this resolved the issue for you?

[notgne2]

I think that issue is just referring to Alpine being one of the few images lacking nsswitch.conf by default and that's why Go are urged to fix it internally, I'll give this a test later today if I get the time.

[notgne2]

Tested on one of the problematic servers without the workaround env supplied, no errors in logs and docker exec -it mc rcon-cli connects just fine