Using the Skytap driver for Docker Machine

Docker Machine is a powerful tool that remotely provisions and manages Docker hosts. The Skytap driver for Docker Machine extends Docker Machine by providing native support for creating and managing Docker hosts running in Skytap.

In this guide, you’ll:

Install Skytap driver for Docker Machine on a local machine.
Use Skytap driver for Docker Machine to create Docker hosts from a VM template in Skytap.
Use Skytap driver for Docker Machine to manage Docker hosts running in Skytap.

docker machine driver diagram

For more information about Docker Machine, visit https://docs.docker.com/machine/overview/.

Requirements

To use the Skytap driver for Docker Machine, you need:

Docker Machine installed on a local computer. For instructions, see: https://docs.docker.com/machine/install-machine/.
Your Skytap Login name and API security token.

To find your Skytap Login name and API security token, see Finding your username and API security token.
A VPN in Skytap and its ID number. Skytap driver for Docker Machine uses a VPN connection to communicate between the local computer network and Skytap remote hosts running in Skytap. To locate your VPN ID, see To Find the ID for a Private Network.

If you do not have a VPN in Skytap, work with your administrator to create one.

Install the Skytap driver for Docker Machine

To install the driver

Download the Skytap driver for Docker Machine here: https://github.com/skytap/docker-machine-driver-skytap/releases.
Follow the installation instructions on that page for your operating system.

Use Skytap driver for Docker Machine to create Docker hosts

After you’ve installed the Skytap driver for Docker Machine, you can begin using the driver to create Docker hosts in Skytap.

In this example, we’ll create a new Docker host from a pre-configured VM in the Skytap public template library.

To create a new Docker host in Skytap

Run the command docker-machine create -d skytap and include the five variables listed below.

--skytap-user-id

Your Skytap user ID.

--skytap-api-security-token

Your API security token.

--skytap-vm-id

ID of a VM in a Skytap template or environment. Docker Machine creates a copy of this VM and automatically connects to it.

Below are VM IDs for pre-configured VMs in the Skytap public library. To use one of these, enter the VM ID in the same region as the Skytap VPN.

Region	VM ID
APAC	9646824
AUS-Sydney	9646822
CAN-Toronto	9646818
EMEA	9646812
US-Central	9646782
US-East	9646778
US-East-2	33274434
US-West	9646772

--skytap-vpn-id

VPN ID to connect to the environment.

<docker-host-name>

Name for the new Docker host.

For example: skytap-machine01

Example command using command line flags

docker-machine create -d skytap \
--skytap-api-security-token 73bc**************** \
--skytap-user-id jane***doe*** \
--skytap-vm-id 9646772 \
--skytap-vpn-id vpn-12345 \
skytap-machine01

These can also be entered in a single command line:

docker-machine create --driver skytap --skytap-user-id jane***doe*** --skytap-api-security-token 73bc**************** --skytap-vm-id 9646772 --skytap-vpn-id vpn-12345 skytap-machine01

To use environment variables instead, see Using environment variables instead of command line flags.

For information about additional command line flags you can include, see Docker create command line flags, environment variables, and default values.

Use Skytap driver for Docker Machine to manage Docker hosts running in Skytap

Once you’ve created Docker hosts in Skytap, you can manage them using Skytap driver for Docker Machine.

The Skytap driver for Docker Machine supports all Docker Machine commands.

For example, to see a list of all hosts (including Skytap-based hosts), enter:

docker-machine ls

Additional information

Docker create command line flags, environment variables, and default values

These flags are available only during the create process.

Docker CLI flag

Environment variable

Description

--skytap-api-logging-level

The logging level to use when running API commands.

info	Default level provides basic information.
debug	Provides detailed information on each REST API call.
warn	Outputs warning messages.
error	Outputs error messages.

If left undefined, the default is info.

--skytap-api-security-token

SKYTAP_API_SECURITY_TOKEN

Your API security token.

--skytap-container-host

SKYTAP_CONTAINER_HOST

Configures the VM as a container host.

--skytap-env-id

SKYTAP_ENV_ID

ID for the environment to add the VM to.

Leave blank to make a new environment.

--skytap-ssh-key

SKYTAP_SSH_KEY

The SSH private key path.

If left undefined, identities in ssh-agent are used.

--skytap-ssh-port

SKYTAP_SSH_PORT

The SSH port.

If left undefined, the default is 22.

--skytap-ssh-user

The SSH user.

If left undefined, the default is docker.

--skytap-user-id

SKYTAP_USER_ID

Your Skytap user ID.

--skytap-vm-cpus

SKYTAP_VM_CPUS

The number of CPUs for the VM. The default is what’s configured for the source VM.

For more information about CPUs and CPUs per socket, see Hardware Settings, CPU.

--skytap-vm-cpuspersocket

SKYTAP_VM_CPUSPERSOCKET

The number of CPU cores in each virtual socket. The default is what’s configured for the source VM.

If you specify the number of CPUs per socket you must also specify the number of CPUs. If you specify the number of CPUs but don’t specify the number of CPUs per socket, each CPU core is allocated to a single virtual socket. The number of CPU cores per socket must be uniformly distributed across the number of sockets (for example, if you have 12 CPUs, the cores per socket must be 1, 2, 3, 4, or 6).

--skytap-vm-id

SKYTAP_VM_ID

ID for the VM template to use.

--skytap-vm-ram

SKYTAP_VM_RAM

The amount of RAM in megabytes. The default is what’s configured for the source VM. For more information about virtual RAM, see CPUs and RAM.

--skytap-vpn-id

SKYTAP_VPN_ID

Private Network ID to connect to the environment.

Using environment variables instead of command line flags

If you prefer not to expose sensitive information, such as your API security token, in a plain text script or command line, you can create environment variables on your local machine.

$ export SKYTAP_USER_ID=jane***doe***
$ export SKYTAP_API_SECURITY_TOKEN=73bc****************
$ docker-machine create --driver skytap {other flags} skytap-machine01

Adjusting VM hardware settings

By default the new Docker host inherits the CPU and memory settings from the source VM. You can override these settings and configure them during the create process. See Docker create command line flags, environment variables, and default values.

VM SSH User credentials

The Docker host templates in the Skytap public template library already contain SSH user credentials. The driver defaults to the SSH user name docker. To use a different SSH user, in a command line, use --skytap-ssh-user <sshusername>. The driver retrieves the password for the SSH user from the VM metadata.

Troubleshooting

You can add -D to any of the Docker Machine commands to run the driver in debug mode and specify a logging level for the Skytap REST API calls, using --skytap=api-logging-level during the create process. See Docker create command line flags, environment variables, and default values.