dmcontext

#!/usr/bin/env bash
# This is a Bash script to create a Docker context that corresponds to 
# the specified Docker Machine created/managed by docker-machine
# It is a context replacement for `eval $(docker-machine env name)`

# Test for sane inputs
if [ "$#" -ne 1 ]; then
    echo "Incorrect number of parameters; please provide only the name of a machine to use to create a context"
    exit 1
fi

if [ "$1" = "--help" ]; then
    echo "Usage: dmcontext <name-of-machine-created-by-docker-machine>"
    exit 0
fi

# Set the name of the machine against which the script will operate
MACHINE=$1

# Set full path to "docker-machine" command; error if not available
DM=$(command -v docker-machine)
if [ -z $DM ]; then
    echo "Can't find docker-machine; exiting..."
    exit 1
fi

# Set full path to "docker" command; error if not available
DCLI=$(command -v docker)
if [ -z $DCLI ]; then
    echo "Can't find Docker CLI; exiting..."
    exit 1
fi

# Test to see if specified Docker Machine exists
TEST=$($DM ls --format '{{ .Name }}' | grep $MACHINE -)
if [ -z $TEST ]; then
    echo "Can't find specified machine; exiting..."
    exit 1
fi

# Check for name collision with existing Docker context
TEST=$($DCLI context ls --format '{{ .Name }}' | grep $MACHINE -)
if [ ! -z $TEST ]; then
    echo "Docker context with that name already exists; exiting..."
    exit 1
fi

# Gather the necessary information about the machine
IPADDR=$($DM inspect $MACHINE --format '{{ .Driver.IPAddress }}')
CA=$($DM inspect $MACHINE --format '{{ .HostOptions.AuthOptions.CaCertPath }}')
CERT=$($DM inspect $MACHINE --format '{{ .HostOptions.AuthOptions.ClientCertPath }}')
KEY=$($DM inspect $MACHINE --format '{{ .HostOptions.AuthOptions.ClientKeyPath }}')

# Create the context
$DCLI context create $MACHINE \
--description "Docker context for $MACHINE" \
--docker "host=tcp://$IPADDR:2376,ca=$CA,cert=$CERT,key=$KEY"