Backend: Agent activity event for configuration changes

Proposal

Any time an agent loads new configuration, KAS should send an activity event (table, model), including

• The agent ID
• Optional: The agent pod
• Optional: The agent pod namespace
• Optional: The configuration project ID (not technically needed because we can retrieve via agent ID)
• The configuration commit SHA
• The time of the event
• The level, kind and details of the event:
  • level=info, kind=get_configuration_success, details="": Means that configuration loaded successfully. No need for details
  • level=warn, kind=get_configuration_with_warnings, details=<warning message>: Means the configuration loaded but there were warnings
  • level=error, kind=get_configuration_errors, details=<error message>: The configuration failed to load.

KAS may send the same (id, sha) twice if the agent has more than one pod.

Rails:

• is not required to persist the pod and namespace for now
• if rails receives the receives the same (agent_id, kind, sha) a second time, a new event should not be generated.

Background

• Design issue #277323 (closed)
• Split out of #350269 (closed)