Set up Dockerized machines

Estimated reading time: 4 minutes

The first step in getting the voting app deployed is to set up Docker machines for the swarm nodes. You could create these Docker hosts on different physical machines, virtual machines, or cloud providers.

For this example, we use Docker Machine to create two virtual machines on a single system. (See Docker Machine Overview to learn more.) We’ll also verify the setup, and run some basic commmands to interact with the machines.

Create manager and worker machines

The Docker Machine command to create a local virtual machine is:

docker-machine create --driver virtualbox <HOSTNAME>

Create two machines and name them to anticipate what their roles will be in the swarm:

  • manager

  • worker

Here is an example of creating the manager. Create this one, then do the same for worker.

$  docker-machine create --driver virtualbox manager
Running pre-create checks...
Creating machine...
(manager) Copying /Users/victoria/.docker/machine/cache/boot2docker.iso to /Users/victoria/.docker/machine/machines/manager/boot2docker.iso...
(manager) Creating VirtualBox VM...
(manager) Creating SSH key...
(manager) Starting the VM...
(manager) Check network to re-create if needed...
(manager) Waiting for an IP...
Waiting for machine to be running, this may take a few minutes...
Detecting operating system of created instance...
Waiting for SSH to be available...
Detecting the provisioner...
Provisioning with boot2docker...
Copying certs to the local machine directory...
Copying certs to the remote machine...
Setting Docker configuration on the remote daemon...
Checking connection to Docker...
Docker is up and running!
To see how to connect your Docker Client to the Docker Engine running on this virtual machine, run: docker-machine env manager

Verify machines are running and get IP addresses

Use docker-machine ls to verify that the machines are running and to get their IP addresses.

$ docker-machine ls
NAME       ACTIVE   DRIVER       STATE     URL                         SWARM   DOCKER        ERRORS
manager   *        virtualbox   Running   tcp://           v1.13.0-rc6
worker    -        virtualbox   Running   tcp://           v1.13.0-rc6

You now have two “Dockerized” machines, each running Docker Engine, accessible through the Docker CLI, and available to become swarm nodes.

You can also get the IP address of a particular machine:

$ docker-machine ip manager

You will need the IP address of the manager for a later step.

Interacting with the machines

There are several ways to interact with these machines directly on the command line or programatically. We’ll cover two methods for managing the machines directly from the command line:

Manage the machines from a pre-configured shell

You can use docker-machine to set up environment variables in a shell that connect to the Docker client on a virtual machine. With this setup, the Docker commands you type in your local shell will run on the given machine. We’ll set up a shell to talk to our manager machine.

  1. Run docker-machine env manager to get environment variables for the manager.

    $ docker-machine env manager
    export DOCKER_TLS_VERIFY="1"
    export DOCKER_HOST="tcp://"
    export DOCKER_CERT_PATH="/Users/victoriabialas/.docker/machine/machines/manager"
    export DOCKER_MACHINE_NAME="manager"
    export DOCKER_API_VERSION="1.25"
    # Run this command to configure your shell:
    # eval $(docker-machine env manager)
  2. Connect your shell to the manager. $ eval $(docker-machine env manager)

    This sets environment variables for the current shell that the Docker client will read which specify the TLS settings.

    Note: If you are using fish, or a Windows shell such as Powershell/cmd.exe the above method will not work as described. Instead, see the env command reference documentation to learn how to set the environment variables for your shell.

  3. Run docker-machine ls again.

    $ docker-machine ls
    NAME      ACTIVE   DRIVER       STATE     URL                         SWARM   DOCKER        ERRORS
    manager   *        virtualbox   Running   tcp://           v1.13.0-rc6   
    worker    -        virtualbox   Running   tcp://           v1.13.0-rc6   

    The asterisk next manager indicates that the current shell is connected to that machine. Docker commands run in this shell will execute on the manager. (Note that you could change this by re-running the above commands to connect to the worker, or open multiple terminals to talk to multiple machines.)

ssh into a machine

You can use the command docker-machine ssh <MACHINE-NAME> to log into a machine:

$ docker-machine ssh manager
                        ##         .
                  ## ## ##        ==
               ## ## ## ## ##    ===
           /"""""""""""""""""\___/ ===
      ~~~ {~~ ~~~~ ~~~ ~~~~ ~~~ ~ /  ===- ~~~
           \______ o           __/
             \    \         __/
 _                 _   ____     _            _
| |__   ___   ___ | |_|___ \ __| | ___   ___| | _____ _ __
| '_ \ / _ \ / _ \| __| __) / _` |/ _ \ / __| |/ / _ \ '__|
| |_) | (_) | (_) | |_ / __/ (_| | (_) | (__|   <  __/ |
|_.__/ \___/ \___/ \__|_____\__,_|\___/ \___|_|\_\___|_|

  WARNING: this is a build from, not a stable release.

Boot2Docker version 1.13.0-rc6, build HEAD : 5ab2289 - Wed Jan 11 23:37:52 UTC 2017
Docker version 1.13.0-rc6, build 2f2d055

We’ll use this method later in the example.

What’s next?

In the next step, we’ll create a swarm across these two Docker machines.

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