Automatically set up boot2docker on a Mac whenever `docker` is called

docker_wrapper.sh

#!/bin/bash

# A wrapper for the docker binary. Checks to make sure the docker host is
# set before executing docker commands.
docker() {

  # Start the daemon if it's not running
  if [ $(boot2docker status) != 'running' ]; then
    echo 'Starting the Docker daemon.'
    boot2docker start
  fi

  if [ -z $DOCKER_HOST ] || [ -z $DOCKER_IP ]; then
    
    # Store the docker binary path
    DOCKER=$(which docker)
    
    # All 'echo' commands are unecessary, but it lets you know
    # if this block of code was run or not.
    echo 'Setting Docker host...'
    
    # Grab the ip address from boot2socker. DOCKER_IP is not
    # necessary to run docker, but it comes in handy (see readme).
    export DOCKER_IP=$(boot2docker ip 2>/dev/null)
    export DOCKER_HOST="tcp://$DOCKER_IP:2375"
    
    # Confirm that variables were exported via the command line.
    echo "    DOCKER_IP=$DOCKER_IP"
    echo "    DOCKER_HOST=$DOCKER_HOST"; echo
  fi

  # Execute docker with all arguments.
  DOCKER "$@"
}

One suggestion, and let me know if this doesn't make sense:

You have the DOCKER_HOST port hardcoded and I noticed right away that sometimes b2d will start with 2376 instead. This means the script will result in:

FATA[0000] Cannot connect to the Docker daemon. Is 'docker -d' running on this host?

I think the better option would be to replace the exporting of $DOCKER_HOST with $(boot2docker shellinit) as this sets them properly

What @MrMMorris said. Here's what's in my .zshrc file now.

boot2docker up
eval `boot2docker shellinit`

Edit: You could probably put an if statement around that boot2docker up to not run it when it's already up.

Pipe stderr to /dev/null if you don't want the "Writing ..." messages to appear.

eval $(boot2docker shellinit 2>/dev/null)

Using this script didn't work immediately for me as I got:

malformed HTTP response "\x15\x03\x01\x00\x02\x02". Are you trying to connect to a TLS-enabled daemon without TLS?

Maybe because Docker (at least in version 1.7?) uses port 2376 by default (and not 2375)? I added the following to make things work.

export DOCKER_CERT_PATH=$HOME/.boot2docker/certs/boot2docker-vm/
export DOCKER_TLS_VERIFY=1

https://gist.github.com/itoche/3bc0ee84f2ae9fee954d