Notes on Molecule

Notes to self...

• Including Ansible variables from the python test file won't interpolate variables that are defined in the same file.  

  For example, this won't work:

  wp_deploy_dir: "/root/wordpress"
  wp_install_dir: "{{ wp_deploy_dir }}/wordpress/web"

  While this does work:

  wp_deploy_dir: "/root/wordpress"
  wp_install_dir: "/root/wordpress/web"

• ansible_env doesn't change with become.  However, the resulting shell environment variables do change, such as $HOME.
• For faster development, it's possible to skip the dependency phase in converge by setting custom converge_sequence in molecule.yml.
• It's possible to debug the tests by:
  1. Run molecule --debug verify to get the exact pytest command that was run and the value for MOLECULE_INVENTORY_FILE.
  2. Go into the scenario directory.
  3. Run the pytest command that you got from step 1, but preface it with a statement that sets MOLECULE_INVENTORY_FILE.
• TravisCI has multiple time limits:
  • Overall build time limit (50 minutes for public repos).
  • Timeout due to no output.
• Molecule docker containers on MacOS are created with the default docker setup.  With Docker Desktop for Mac, this means that Docker—and therefore the molecule container—are running inside a hyperkit virtual machine.
  • To "log in" to the VM running the container, use the screen command to attach to an existing terminal session inside the machine:
    

    $ screen ~/Library/Containers/com.docker.docker/Data/vms/0/tty

     

• host.run() actually runs commands with the Ansible command module.  Variable interpolation does happen at this point, but the variables must be in the global Ansible runner namespace.