A basic shell script to use a configuration file to update local development hosts ip running on docker-machine (virtual box) and Mac OSX

docker-machine-update-hosts.sh

#!/usr/bin/env bash
#Usage docker-machine-update-hosts.sh hosts.conf default
#arg1 is a configuration file with hosts
#arg2 is the docker-machine name e.g. default

DOCKER_IP=$(docker-machine ip $2)
echo "$2 ip: $DOCKER_IP"

#Remove existing lines from hosts
while IFS='' read -r line || [[ -n "$line" ]]; do
  echo "Removing existing domain $line"
  sudo sed -i '' '/'$line'/d' /etc/hosts
done < "$1"

#Add new hosts to the bottom of the file
while IFS='' read -r line || [[ -n "$line" ]]; do
  echo "Adding entry $DOCKER_IP $line"
  sudo echo "$DOCKER_IP $line" >>/etc/hosts
done < "$1"

hosts.conf

example.dev
other-site.local
my-site.com

you could do:

machine_name=${2:-$(docker-machine active)}
DOCKER_IP="$(docker-machine ip $machine_name)"

if you wanted to default the second parameter to the "active" docker-machine name.