[Enhancement] VMware Fusion driver

[mschygulla]

This PR enhances the Docker Machine driver for VMware Fusion (OSX). It add's an additional cdrom as configuration drive datasource for the Cloud-init package. An example config drive which was tested with CoreOS can be found here: https://github.com/mschygulla/configdrive

The driver accepts some new flags:

URL for cloud-init configdrive

• EnvVar: "FUSION_CONFIGDRIVE_URL"
• Name: "vmwarefusion-configdrive-url"

SSH user (default is B2DUser)

• EnvVar: "FUSION_SSH_USER"
• Name: "vmwarefusion-ssh-user"

SSH password (default is B2DPass)

• EnvVar: "FUSION_SSH_PASSWORD"
• Name: "vmwarefusion-ssh-password"

If the flag --vmwarefusion-configdrive-url is not used, the driver will behave as before.

If an URL is specified with the flag --vmwarefusion-configdrive-url, the driver will download the ISO and create an additional cdrom in the VMX file with the provided ISO. Since the VMware Tools are not always available, the generated public SSH key will be copied with SSH using the provided SSH User/Password.

This PR was tested with CoreOS and the CoreOS provisioner (#1463)

Example Usage:

$ docker-machine create -d vmwarefusion --vmwarefusion-boot2docker-url http://alpha.release.core-os.net/amd64-usr/723.0.0/coreos_production_iso_image.iso --vmwarefusion-configdrive-url https://github.com/mschygulla/configdrive/releases/download/v0.2/configdrive.iso --vmwarefusion-ssh-user core dev

or

$ export FUSION_BOOT2DOCKER_URL=http://alpha.release.core-os.net/amd64-usr/723.0.0/coreos_production_iso_image.iso
$ export FUSION_CONFIGDRIVE_URL=https://github.com/mschygulla/configdrive/releases/download/v0.2/configdrive.iso
$ export FUSION_SSH_USER=core

$ docker-machine create -d vmwarefusion dev1
$ docker-machine create -d vmwarefusion dev2

Feedback welcome :)

[nathanleclaire]

cc @frapposelli

[frapposelli]

LGTM!