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Provision a Swarm cluster with Docker Machine

You can use Docker Machine to provision a Docker Swarm cluster. Machine is the Docker provisioning tool. Machine provisions the hosts, installs Docker Engine on them, and then configures the Docker CLI client. With Machine’s Swarm options, you can also quickly configure a Swarm cluster as part of this provisioning.

This page explains the commands you need to provision a basic Swarm cluster on a local Mac or Windows computer using Machine. Once you understand the process, you can use it to setup a Swarm cluster on a cloud provider, or inside your company’s data center.

If this is the first time you are creating a Swarm cluster, you should first learn about Swarm and its requirements by installing a Swarm for evaluation or installing a Swarm for production. If this is the first time you have used Machine, you should take some time to understand Machine before continuing.

What you need

If you are using Mac OS X or Windows and have installed with Docker Toolbox, you should already have Machine installed. If you need to install, see the instructions for Mac OS X or Windows.

Machine supports installing on AWS, Digital Ocean, Google Cloud Platform, IBM Softlayer, Microsoft Azure and Hyper-V, OpenStack, Rackspace, VirtualBox, VMware Fusion®, vCloud® AirTM and vSphere®. In this example, you’ll use VirtualBox to run several VMs based on the boot2docker.iso image. This image is a small-footprint Linux distribution for running Engine.

The Toolbox installation gives you VirtualBox and the boot2docker.iso image you need. It also gives you the ability provision on all the systems Machine supports.

Note:These examples assume you are using Mac OS X or Windows, if you like you can also install Docker Machine directly on a Linux system.

Provision a host to generate a Swarm token

Before you can configure a Swarm, you start by provisioning a host with Engine. Open a terminal on the host where you installed Machine. Then, to provision a host called local, do the following:

docker-machine create -d virtualbox local

This examples uses VirtualBox but it could easily be DigitalOcean or a host on your data center. The local value is the host name. Once you create it, configure your terminal’s shell environment to interact with the local host.

eval "$(docker-machine env local)"

Each Swarm host has a token installed into its Engine configuration. The token allows the Swarm discovery backend to recognize a node as belonging to a particular Swarm cluster. Create the token for your cluster by running the swarm image:

docker run swarm create
Unable to find image 'swarm' locally
1.1.0-rc2: Pulling from library/swarm
892cb307750a: Pull complete
fe3c9860e6d5: Pull complete
cc01ef3f1fbc: Pull complete
b7e14a9c9c72: Pull complete
3ec746117013: Pull complete
703cb7acfce6: Pull complete
d4f6bb678158: Pull complete
2ad500e1bf96: Pull complete
Digest: sha256:f02993cd1afd86b399f35dc7ca0240969e971c92b0232a8839cf17a37d6e7009
Status: Downloaded newer image for swarm
0de84fa62a1d9e9cc2156111f63ac31f

The output of the swarm create command is a cluster token. Copy the token to a safe place you will remember. Once you have the token, you can provision the Swarm nodes and join them to the cluster_id. The rest of this documentation, refers to this token as the SWARM_CLUSTER_TOKEN.

Provision Swarm nodes

All Swarm nodes in a cluster must have Engine installed. With Machine and the SWARM_CLUSTER_TOKEN you can provision a host with Engine and configure it as a Swarm node with one Machine command. To create a Swarm master node on a new VM called swarm-master, you do the following:

docker-machine create \
    -d virtualbox \
    --swarm \
    --swarm-master \
    --swarm-discovery token://SWARM_CLUSTER_TOKEN \
    swarm-master

Then, provision additional an additional node. You must supply the SWARM_CLUSTER_TOKEN and a unique name for each host node, HOST_NODE_NAME.

docker-machine create \
    -d virtualbox \
    --swarm \
    --swarm-discovery token://SWARM_CLUSTER_TOKEN \
    HOST_NODE_NAME

For example, you might use node-01 as the HOST_NODE_NAME in the previous example.

Note: These command rely on Docker Swarm’s hosted discovery service, Docker Hub. If Docker Hub or your network is having issues, these commands may fail. Check the Docker Hub status page for service availability. If the problem Docker Hub, you can wait for it to recover or configure other types of discovery backends.

Connect node environments with Machine

If you are connecting to typical host environment with Machine, you use the env subcommand, like this:

eval "$(docker-machine env local)"

Docker Machine provides a special --swarm flag with its env command to connect to Swarm nodes.

docker-machine env --swarm HOST_NODE_NAME
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.101:3376"
export DOCKER_CERT_PATH="/Users/mary/.docker/machine/machines/swarm-master"
export DOCKER_MACHINE_NAME="swarm-master"
# Run this command to configure your shell:
# eval $(docker-machine env --swarm HOST_NODE_NAME)

To set your SHELL connect to a Swarm node called swarm-master, you would do this:

eval "$(docker-machine env --swarm swarm-master)"

Now, you can use the Docker CLI to query and interact with your cluster.

docker info
Containers: 2
Images: 1
Role: primary
Strategy: spread
Filters: health, port, dependency, affinity, constraint
Nodes: 1
 swarm-master: 192.168.99.101:2376
  └ Status: Healthy
  └ Containers: 2
  └ Reserved CPUs: 0 / 1
  └ Reserved Memory: 0 B / 1.021 GiB
  └ Labels: executiondriver=native-0.2, kernelversion=4.1.13-boot2docker, operatingsystem=Boot2Docker 1.9.1 (TCL 6.4.1); master : cef800b - Fri Nov 20 19:33:59 UTC 2015, provider=virtualbox, storagedriver=aufs
CPUs: 1
Total Memory: 1.021 GiB
Name: swarm-master

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https://docs.docker.com/v1.10/swarm/provision-with-machine/