Description of the worker interaction

worker.rst

Workers are specialized as follows:

• OpenStack Ansible, consuming that endpoint - we may want to assume Docker here
• Generalized Docker-based commands, using docker-py to wrap

All workers have the following environment variables set:

• CRATON_URL - URL for the Craton API endpoint
• CRATON_TOKEN - time-limited, scoped token (inventory + keys) for working with the Craton service
• CRATON_TASK - the specific task ID being run here to support lookup of the task details
• CRATON_DEVICES - whitespace separated list of device IDs that the worker is responsible for (possibly empty)

Workers coordinate with the Craton service as follows:

.. seqdiag::

   seqdiag {
     service -> jobboard [label="setup tasks"];
     jobboard -> worker [label="run task using env vars"];
     worker -> service [label="get task config"];
     worker -> service [label="get ansible inventory on devices"];
     worker -> device [label="run playbook on devices"];
     device -> worker [label="results via callback API"];
     worker -> service [label="set variables in inventory"];
     worker -> jobboard [label="task completion"];
     jobboard -> worker [label="retry"];  # FIXME this needs to use the correct seq diag stuff here
   }