Setting up saltstack locally with docker

Docker Compose setup to spin up a salt master and minion.

Requirements:

• docker (18.09.2+)
• docker-compose (1.23.2+)

(*Tested Versions)

Setup

Before firing docker-compose, first build the base image used by it:

./bin/build-base-image.sh

This will create a centos7 base image with enabled systemd (System and Service Manager), to run multiple services within the same container. (FYI: Have in mind that Docker was designed to run container per service, that's why enabling systemd is considered dangerous and has maltitude of consequences).

To use the new image to build salt-master and salt-minion images run:

docker-compose build

To start master and minion run:

./bin/start.sh

Console output from instances is redirected to ./docker-compose.log file.

To log in into master or minion run:

./bin/login-{master,minion}.sh with suffix matching specific instance.

To validate the installation run one of below commands from master:

salt-key

or

salt '*' test.ping

Result should contain two minions:

• salt-master (as his own minion)
• salt-minion (as a minion only)

Cluster configuration

To change cluster configuration first take a look at setup of ./config folders.

To define roles which should be installed by minions (or any other extra static information), grains can be used. Keep in mind that those roles have to be correctly structured in base, pillar, overrides. Example of such roles are available under master/srv/base/samples. Roles can be used to define for example services or packages that should be installed on a minion.

All minions are by default configured to install yum repositories defined in master/srv/pillar/core/repositories in case you need some specific ones. In case you cannot reach some repository to install required packages you can copy them directly into master/srv/base/pillar/overrides structure or create a yum artifact and copy it into master/tmp/extras

Simplifications

Master has a few aliases built in to make working with it easier:

alias base='cd /srv/salt/base

alias pillar='cd /srv/salt/pillar

alias overrides='cd /srv/salt/pillar/overrides

alias saltlogs='cd /var/log/salt

Built in editing tools: less, vim.

Creating image from salt-minion

In case you want to create reusable image from salt-minion, you can run:

./bin/generate-image-from-salt-minion.sh

Have in mind that everything related to salt itself will be removed in the process to leave a clean container with salt configuration applied.

Learning

You may take a look at this Official Tutorial.

Troubleshooting

FYI: you will see log messages like : "Could not determine init system from command line" - those are just because salt is running in the foreground and not from an auto-startup.

The salt-master is set up to accept all minions that try to connect. Since the network that the salt-master sees is only the docker-compose network, this means that only minions within this docker-compose service network will be able to connect (and not random other minions external to docker).