Let's say something like this is being returned when using the molecule CLI.

]$ molecule test
CRITICAL Failed to find driver docker. Please ensure that the driver is correctly installed.

The molecule drivers command can be used to determine if you have the driver installed. In this example, the docker driver is not listed.

]$ molecule drivers
default

And the pip list command can be used to see that the molecule package is installed but the TBD package is NOT installed.

]$ pip list
Package                   Version
------------------------- ---------
ansible-compat            25.1.5
ansible-core              2.18.4
attrs                     25.3.0
bracex                    2.5.post1
cffi                      1.17.1
click                     8.1.8
click-help-colors         0.9.4
cryptography              44.0.2
enrich                    1.2.7
Jinja2                    3.1.6
jsonschema                4.23.0
jsonschema-specifications 2024.10.1
markdown-it-py            3.0.0
MarkupSafe                3.0.2
mdurl                     0.1.2
molecule                  25.4.0
packaging                 24.2
pip                       25.0.1
pluggy                    1.5.0
pycparser                 2.22
Pygments                  2.19.1
PyYAML                    6.0.2
referencing               0.36.2
resolvelib                1.0.1
rich                      14.0.0
rpds-py                   0.24.0
subprocess-tee            0.4.2
typing_extensions         4.13.1
wcmatch                   10.0

Let's install the docker plugin.

pip install molecule-plugins[docker]

And now pip should install molecule-plugins and docker.

]$ pip list
Package                   Version
------------------------- ---------
ansible-compat            25.1.5
ansible-core              2.18.4
attrs                     25.3.0
bracex                    2.5.post1
certifi                   2025.1.31
cffi                      1.17.1
charset-normalizer        3.4.1
click                     8.1.8
click-help-colors         0.9.4
cryptography              44.0.2
distro                    1.9.0
docker                    7.1.0
enrich                    1.2.7
idna                      3.10
Jinja2                    3.1.6
jsonschema                4.23.0
jsonschema-specifications 2024.10.1
markdown-it-py            3.0.0
MarkupSafe                3.0.2
mdurl                     0.1.2
molecule                  25.4.0
molecule-plugins          23.7.0
packaging                 24.2
pip                       25.0.1
pluggy                    1.5.0
pycparser                 2.22
Pygments                  2.19.1
PyYAML                    6.0.2
referencing               0.36.2
requests                  2.32.3
resolvelib                1.0.1
rich                      14.0.0
rpds-py                   0.24.0
selinux                   0.3.0
subprocess-tee            0.4.2
typing_extensions         4.13.1
urllib3                   2.3.0
wcmatch                   10.0

And the molecule plugins should include docker and probably other plugins too.

]$ molecule drivers
openstack
gce
azure
default
ec2
containers
docker
podman
vagrant