docker: add nsswitch.conf to base layer

[rvl]

Overview

Configures the docker image to use /etc/hosts ahead of DNS.

This works around the issue of the CLI being hardcoded to use localhost.

Comments

Before:

docker run --network host --rm -ti --entrypoint=bash inputoutput/cardano-wallet:2020.7.28-shelley
bash-4.4# ping localhost
PING localhost(localhost.lan (::1)) 56 data bytes
64 bytes from localhost.lan (::1): icmp_seq=1 ttl=64 time=0.043 ms
64 bytes from localhost.lan (::1): icmp_seq=2 ttl=64 time=0.087 ms
64 bytes from localhost.lan (::1): icmp_seq=3 ttl=64 time=0.092 ms
^C
--- localhost ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2043ms
rtt min/avg/max/mdev = 0.043/0.074/0.092/0.022 ms
bash-4.4# cat /etc/nsswitch.conf
cat: /etc/nsswitch.conf: No such file or directory

After:

docker run --network host --rm -ti --entrypoint=bash inputoutput/cardano-wallet:2020.7.28-shelley
bash-4.4# ping localhost
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.047 ms
64 bytes from localhost (127.0.0.1): icmp_seq=2 ttl=64 time=0.081 ms
64 bytes from localhost (127.0.0.1): icmp_seq=3 ttl=64 time=0.078 ms
^C
--- localhost ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2062ms
rtt min/avg/max/mdev = 0.047/0.068/0.081/0.015 ms
bash-4.4# cat /etc/nsswitch.conf
hosts: files dns

[KtorZ]

LGTM. What about also changing the BaseUrl constructed in the CLI to not use localhost?

[rvl]

The issue for that is (was) #949.

[runeksvendsen]

This works around the issue of the CLI being hardcoded to use localhost.

How do I work around this issue, exactly?

[rvl]

Hello @runeksvendsen. There is currently no way to use the cardano-wallet CLI client with a non-localhost server.

If you need to call the API of a cardano-wallet server running on another host, you can:

1. Use curl to make your API requests instead of cardano-wallet.
2. port forward the remote server to a localhost port, then use cardano-wallet --port=PORT

Just make sure that the API server is running with the correct --listen-address option.

The changes in this PR achieved something different to what you probably want. This PR makes it at least possible to use the cardano-wallet CLI client inside the same Docker container which the server is running on.