Deploy Consul server agent on Docker

This topic provides an overview for deploying a Consul server when running Consul on Docker containers.

Prerequisites

Docker

You will need a local install of Docker running on your machine for this tutorial. You can find the instructions for installing Docker on your specific operating system here.

Consul (Optional)

If you would like to interact with your containerized Consul agents using a local install of Consul, follow the instructions here and install the binary somewhere on your PATH.

Get the Docker image

First, pull the latest image. You will use Consul's official Docker image in this tutorial.

$ docker pull consul

Check the image was downloaded by listing Docker images that match consul.

$ docker images -f 'reference=consul'

REPOSITORY     TAG      IMAGE ID        CREATED             SIZE
consul       latest    8b6c5f52aa82   18 hours ago   149MB

Configure and run a Consul server

Next, you will use Docker command-line flags to start the agent as a server, configure networking, and bootstrap the datacenter when one server is up.

$ docker run \
    -d \
    -p 8500:8500 \
    -p 8600:8600/udp \
    --name=badger \
    consul agent -server -ui -node=server-1 -bootstrap-expect=1 -client=0.0.0.0

Since you started the container in detached mode, -d, the process will run in the background. You also set port mapping to your local machine as well as binding the client interface of our agent to 0.0.0.0. This allows you to work directly with the Consul datacenter from your local machine and to access Consul's UI and DNS over localhost. Finally, you are using Docker's default bridge network.

Note, the Consul Docker image sets up the Consul configuration directory at /consul/config by default. The agent will load any configuration files placed in that directory.

To avoid mounting volumes or copying files to the container, you can also save configuration JSON to that directory via the environment variable CONSUL_LOCAL_CONFIG, which will be covered later in the tutorial.

Discover the server IP address

You can find the IP address of the Consul server by executing the consul members command inside of the badger container.

$  docker exec badger consul members

Node      Address          Status  Type    Build   Protocol  DC   Partition  Segment
server-1  172.17.0.2:8301  alive   server  1.13.3  2         dc1  default    <all>