[Ingest manager] Agent degraded status

[blakerouse]

Description

Currently agent knows about a status of Degraded, which means that Agent is running, but it's currently in a degraded state (at the moment it's just reported as Running). Agent sends the reason for degraded, that could be like "system/load metricset doesn't exist".

This would be great to show to the user in the Fleet UI, so its more obvious that the Agent is not perfectly healthy.

[elasticmachine]

Pinging @elastic/ingest-management (Team:Ingest Management)

[nchaulet]

@blakerouse on the fleet side how we can know an agent is in a degraded state?

[blakerouse]

@nchaulet Agent can send the status of Degraded to Fleet, and once it goes back to Healthy it will resend that status.

[nchaulet]

Sounds great we can add a new field to the checkin, do you think there is another info missing that you can send at the same time or it will just be inside events?

[blakerouse]

At the moment it will just be the message of what is degraded, so it should match the current UI for "Activity log". Which is the same as reporting failure.