GitLab CI: docker: ansible: No config file found; using defaults

$ ansible-playbook -v --private-key $SSH_PRIVATE_KEY playbooks/letsencrypt.yml
[WARNING]: Ansible is being run in a world writable directory
(/builds/devops/letsencrypt), ignoring it as an ansible.cfg source. For more
information see
https://docs.ansible.com/ansible/devel/reference_appendices/config.html#cfg-in-world-writable-dir
No config file found; using defaults
[WARNING]: No inventory was parsed, only implicit localhost is available
[WARNING]: provided hosts list is empty, only localhost is available. Note that
the implicit localhost does not match 'all'
ERROR! the role 'letsencrypt' was not found in /builds/devops/letsencrypt/playbooks/roles:/root/.ansible/roles:/usr/share/ansible/roles:/etc/ansible/roles:/builds/devops/letsencrypt/playbooks

The error appears to be in '/builds/devops/letsencrypt/playbooks/letsencrypt.yml': line 6, column 7, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  roles:
    - { role: letsencrypt }
      ^ here
section_end:1657096760:step_script