Docker - Get started

Requirements

• Docker tools v18.09.3 or equivalent Docker desktop
• A virtual machine monitor compatible with docker-machine

Setup swarm

Before setting up the swarm, its recommended to create some docker hosts using the installed virtual machine manager. Using virtualbox for example, the hosts can be created by running:

docker-machine create --driver virtualbox <host_name>

The host managed by docker-machine can be listed with:

docker-machine ls

Setup swarm manager

For a machine to act as swarm manager, we need to init the swarm in it as follows:

docker-machine ssh <swarm_manager_host_name> "docker swarm init"

The output of this command will generate a default docker command that can be used to add machines to the swarm.

After this, we need to perfom an extra step so that the redis service can correctly persist data:

docker-machine ssh <swarm_manager_host_name> "mkdir ./data"

The state of the swarm can be checked by running:

docker node ls

Setup swarm nodes

Machines can be added to the swarm by using the output of docker swarm init by running:

docker-machine ssh <host_name> <swarm_init_output>

Start stack

In order to access local files when running docker commands on the swarm manager, we need to set the shell environment to talk to it.

First, run:

docker-machine env <swarm_manager_host_name>

This will output some env. variable values and a command on its last line that needs to be run in order to set the target of the shell environment.

After doing this, we can deploy the stack by running:

docker stack deploy -c docker-compose.yml <stack_name>

For subsequent changes on the composition of the services to be applied on the stack, just run:

docker stack deploy -c docker-compose.yml <stack_name>

To teardown the stack, run:

docker stack rm <stack_name>

Available services

• Redis
• Docker visualizer
• Flask web application