Test Docker-related Ansible roles with Travis and Molecule

Sunday. September 03, 2017 - 2 mins

ansible docker deployment molecule devops travis ci

Problem

Molecule is probably the most simple and effective way to test Ansible roles. By default it uses Docker containers to provide hosts for test environments, but things get complicated if your role manipulates with Docker containers. If using Docker driver, you’ll end up with Docker-in-docker setup, which isn’t stable, complicated and won’t work in many cases.

Recently, 2.0 version of Molecule was released. It introduced new driver, called delegated. With that driver, Molecule skips provisioning/deprovisioning steps, allowing you to manage instances manually. Also, you need to provide configuration, describing how to connect to those instances. This will allow you to test against remote hosts or to use local connection.

Configure Molecule

Travis provisions a new virtual machine for each run, so you don’t need to care about provisioning. To make Molecule run tests into provisioned Travis VM, we need to modify molecule.yml to use delegated driver and local method to connect.

driver:
  name: delegated
  options:
    ansible_connection_options:
      connection: local
platforms:
  - name: delegated-travis-instance

But that’s not enough, cause Ansible will still try to connect via SSH, to change that behaviour, you need to set ansible_connection to local for Travis VM.

provisioner:
  name: ansible
  inventory:
    host_vars:
      delegated-travis-instance:
        ansible_connection: local

Travis configuration

Here’s an example of .travis.yml

---
dist: trusty
sudo: required

language: python
python:
  - "2.7"

services:
  - docker

before_install:
  - deactivate
  - |
    sudo apt-key adv --recv-keys \
      --keyserver keyserver.ubuntu.com 3B4FE6ACC0B21F32 40976EAF437D05B5
  - sudo apt-get update -qq
  - sudo apt-get install -y -o Dpkg::Options::="--force-confnew" docker-ce

install:
  - sudo pip install ansible ansible-lint docker-py molecule
  - ansible --version
  - molecule --version

script:
  - molecule test

Working example

Working example of setup I’ve described above, you can find here.

Roman Komkov

Creating and maintaining modern solid infrastructures