Fix Docker4Mac container routeability (steps needed every host VM restart)

docker.fix-network

#!/usr/bin/env bash

## Make Docker4Mac containers routable in a private network.
## This is mostly a copy-paste from the original solution.
## IT'S NOT A COMPLETE SOLUTION - this script only does the
## steps necessary every time Docker4Mac is restarted.
## Beforehand, you have to run the steps marked as ONCE yourself.
## See https://github.com/docker/for-mac/issues/155#issuecomment-320509769

set -e

: NET_NAME=dev_nw
NET_RANGE=10.11.12.0/24
HOST_IFACE=${HOST_IFACE:-eth1}
BRIDGE_IFACE=bridge100

GATEWAY=$(docker run --rm --net=host --pid=host --privileged -it justincormack/nsenter1 /bin/sh -c "ipaddr show $HOST_IFACE | grep inet[^6] | awk '{ print \$2 }' | cut -d/ -f1")
docker run --rm --net=host --pid=host --privileged -it justincormack/nsenter1 /usr/local/sbin/iptables -I FORWARD -i $HOST_IFACE -j ACCEPT
NATIVE_IFACE=$(ifconfig bridge100 | grep member | awk '{ print $2 }')
sudo ifconfig $BRIDGE_IFACE deletem $NATIVE_IFACE
sudo ifconfig $BRIDGE_IFACE addm $NATIVE_IFACE
sudo route add $NET_RANGE $GATEWAY