Ansible Testing with Molecule Flashcards

In Molecule's molecule.yml, what does the 'platforms' section define?

Answer: The test instances (containers/VMs) to create, including their names, images, and configuration

The 'platforms' section specifies what test instances Molecule should create—their names, Docker images, OS versions, etc.

What is Molecule's 'idempotency' test and why is it important?

Answer: Molecule runs the converge playbook twice and fails if any task reports 'changed' on the second run, verifying that the role doesn't make unnecessary changes

The idempotency check enforces a core Ansible principle—a properly written role should only make changes when needed, not on every run.

How do you run Molecule tests for a specific scenario when multiple scenarios exist?

Answer: molecule test --scenario-name scenarioname

The '--scenario-name' flag (or '-s' shorthand) specifies which scenario to run when a role has multiple test scenarios.

What is the purpose of Molecule's 'prepare' phase?

Answer: It runs a prepare.yml playbook to configure test prerequisites on instances before the role under test is applied

The prepare phase runs before converge to set up any prerequisites that the role expects (users, directories, packages) without those prerequisites being part of the role itself.

How does Molecule integrate with CI/CD pipelines like GitHub Actions or GitLab CI?

Answer: Molecule runs as a standard CLI tool in pipeline jobs; Docker-in-Docker or Docker socket mounting is needed for the Docker driver

Molecule is a standard Python CLI tool that runs in any CI environment with Docker and Python available.

What is the 'delegated' Molecule driver used for?

Answer: It delegates instance management to custom playbooks (create.yml and destroy.yml), enabling Molecule to work with any infrastructure not supported by built-in drivers

The delegated driver allows complete customization of instance lifecycle—create and destroy playbooks handle infrastructure provisioning, enabling testing on any platform.