Impossible to use a custom driver

[gciavarrini]

Issue Type

• Bug report

Molecule and Ansible details

ansible --version && molecule --version

ansible [core 2.12.10]
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/gloria/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.10/site-packages/ansible
  ansible collection location = /home/gloria/.ansible/collections:/usr/share/ansible/collections
  executable location = /usr/bin/ansible
  python version = 3.10.8 (main, Nov 14 2022, 00:00:00) [GCC 12.2.1 20220819 (Red Hat 12.2.1-2)]
  jinja version = 3.1.2
  libyaml = True
molecule 4.0.0 using python 3.10 
    ansible:2.12.10
    delegated:4.0.0 from molecule
    custom-driver-name:0.0.4 from custom_driver_name

Molecule installation method (one of):

• pip

Ansible installation method (one of):

• pip

Detail any linters or test runners used:

Desired Behavior

We are developing a custom molecule driver.
Unfortunately, at the moment, it seems no possible to use it.

The reasons that pushed us to create a custom driver are:

• It is possible to import a driver in multiple project (no code duplication)
• The delegated driver needs to be re-implemented every time
• If the custom driver needs to be modified, all the modifications will be available in all the projects that use it.

Actual Behaviour

First, we install the custom driver:

pip install custom_driver_name

Then, we check that it is listed among the molecule drivers

>> molecule drivers
╶───────────────────────────────────────────────────────── 
delegated 
custom_driver_name                                                                                                                                                                                                                                                                                                                   

But then, when we try to use it from molecule <command> -d custom_driver_name the following error is shown:

Error: Invalid value for '--driver-name' / '-d': 'custom_driver_name is not one of 'delegated', 'docker', 'podman'.

This is error is due to a validation fail

Possible solution

A possible solution is to define a prefix (e.g. custom-) or a set of prefix (e.g. custom-, molecule-, ... ) that make possible the validation. This will make the validation more flexible while maintaining the guarantee that the user is not misspelling standard driver names.

[apatard]

Looks like a duplicate of #3689. Look at #3765 which tries to improve things [ I hoped to find time to look at this PR but still -ENOTIME ].

[gciavarrini]

@apatard Thank you for pointing out #3689: I missed it!

Since the proposed solution in #3765 is still under development, and it seems a bit complex, I'd like to propose to the community my idea of allowing driver name with prefixes molecule or custom.
I created a draft PR #3795 to demonstrate and, hopefully, discuss the idea.

Feel free to close this issue if you think it's best :)

[gciavarrini]

Resolved by PR #3795.