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RedHat - Ansible

Molecule

Molecule is a framework to run automated tests for Ansible playbooks/roles.

Here I will go into how to set it up and use it. (basically)

Install

Install testing tools:

pip3 install molecule molecule-docker

Running

cd PATH/TO/ROLE  # p.e. "cd /home/guy/ansible/roles/infra_wireguard"

# to run build the test instances, run the tests and clean up afterwards
molecule test
# for troubleshooting
molecule create
# now we can run the actual playbook as many times as we need/want
molecule converge
# test it
molecule verify
# clean it up when we finished troubleshooting
molecule destroy

AnsibleGuy Roles

AnsibleGuy Roles use Docker as testing-platform.

These steps have to be performed before running the tests:

  1. You need to install molecule version '4.0.1' python3 -m pip install molecule==4.0.1!

    Why?

    I use YAML-anchors to keep my molecule configuration to a minimum - the current version of molecule does not allow those to be defined. See: molecule issue 3689

  2. Add the 'molecule-docker.local' DNS-Record to your '/etc/hosts' file and point it to your docker-server to use.

  3. You will have to add the 'DOCKER_HOST' environmental variable:

export DOCKER_HOST="tcp://molecule-docker.local:2375"

Troubleshooting

Run in debug mode and enable command-logging:

MOLECULE_NO_LOG=false molecule --debug create

Platform

Molecule dynamically creates VMs or Containers that are used as target for you Ansible playbook to test.

There are some options to choose from:

There are some usage differences between those platforms.

I'll only go into the details of platforms I've experience with.

Docker

You need a docker server/instance to deploy the test-servers to.

Install

Install docker as described here

sudo apt-get update
sudo apt-get -y install ca-certificates curl gnupg lsb-release

Add the repository

# ubuntu
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
# debian
curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update

Configure

Either way - the docker server must have the following setting configured in '/etc/docker/daemon.json':

{"cgroup-parent": "docker.slice"}

Restart docker after adding that setting. This allows systemd to work inside the container without mapping cgroup manually.

For further information see: serverfault.com

Locally

This is only recommended if you have powerful hardware and/or very simple role-tests.

Some of my roles use 10+ containers and therefor use a good amount of RAM/CPU at peak times.

You will have to set-up docker as described here.

Switch the docker_host to your local one. (${role}/molecule/default/molecule.yml)

docker_host: 'unix://var/run/docker.sock'  # localhost

Remote

Installation

sudo apt-get -y install docker-ce-cli

As mentioned before/above - we recommend running the testing on a server.

You might want to consider using the docker role to provision a docker server as a vm.

You will have to configure the ip-address to your docker-server. (${role}/molecule/default/molecule.yml)

docker_host: 'tcp://IP:PORT'  # p.e. tcp://172.17.0.50:2375

But it seems like the docker module does not get the molecule config. (Still connecting to localhost)

Therefore, you will have to set this environmental variable in addition:

export DOCKER_HOST='tcp://IP:PORT'