Docker swarm creation script

docker-swarm-cluster.sh

#!/bin/bash

MANAGER=${1:-2}
WORKER=${2:-3}

#=========================
# Creating cluster members
#=========================
echo "### Creating $MANAGER managers"
echo "### Creating $WORKER workers"
for i in $(seq 1 $MANAGER); do
  docker-machine create --driver virtualbox swarm-manager$i
done

for i in $(seq 1 $WORKER); do
  docker-machine create --driver virtualbox swarm-worker$i
done

#===============
# Starting swarm
#===============
MANAGER_IP=$(docker-machine ip swarm-manager1)
echo "### Initializing main master: swarm-manager$i"
docker-machine ssh swarm-manager1 docker swarm init \
  --advertise-addr $MANAGER_IP

#===============
# Adding members
#===============
MANAGER_TOKEN=$(docker-machine ssh swarm-manager1 docker swarm join-token --quiet manager)
WORKER_TOKEN=$(docker-machine ssh swarm-manager1 docker swarm join-token --quiet worker)

for i in $(seq 2 $MANAGER); do
  echo "### Joining manager: swarm-manager$i"
  docker-machine ssh swarm-manager$i docker swarm join \
  --token $MANAGER_TOKEN \
  $MANAGER_IP:2377
done
for i in $(seq 1 $WORKER); do
  echo "### Joining worker: swarm-manager$i"
  docker-machine ssh swarm-worker$i docker swarm join \
  --token $WORKER_TOKEN \
  $MANAGER_IP:2377
done

docker-machine ssh swarm-manager1 docker node ls

echo "### Join your client to the cluster using:"
echo "  eval \$(docker-machine env swarm-manager1)"
echo "### or run using:"
echo "  docker-machine ssh swarm-manager1 docker node ls"

Maybe the docker command and the driver should be overridable with env variables?