Add the IP of a dockerhost to the /etc/hosts file of a Docker container if not already there.

dockerhost.sh

#!/bin/bash
if [[ -z $(grep dockerhost /etc/hosts) ]]
then
    echo `/sbin/ip route|awk '/default/ { print $3 }'` dockerhost >> /etc/hosts
fi

I wish I could star this multiple times, and it's also taught me a bit more AWK

I'm seeing $3 as the subnet default-gateway and $7 as the local dockerhost interface IP.

This gives the gateway ip and not the docker host ip.

@sburnwal but docker host is the gateway, isn't it? In what kind of config is docker host not the gateway of docker containers?

Note that if your host is Mac, the 172.17.0.1 will be a wrong answer. Use dedicated DNS name docker.for.mac.localhost instead.