[Feature Request] Provide worker status

[cretz]

Describe the solution you'd like

Users need to get worker status to at least check worker health and programmatically react to information we often only make available via logs/metrics. This should be a common design applied to all SDKs. What should be made available (all subject to discussion):

• Current activity slots in use
• Current workflow slots in use (debatable since this comes and goes so quick)
• Current workflow cache size (in SDKs that aren't using global caches)
• Current status per worker type - e.g. "polling", "full", or "failure backoff"
  • Make sure failure backoff includes the error
  • Consider way to notify user programmatically upon status change
• Server reachable (i.e. that client doesn't have any server errors)

Per-SDK Tickets

• Go - TODO
• Java - TODO
• Core - TODO
• TypeScript - TODO
• Python - TODO
• .NET - TODO
• Ruby - TODO
• PHP - TODO
• Temporal CLI - TODO

[dannymcerlean1]

+1. This would be really helpful for monitoring.

[yuandrew]

Created a separate, related issue for worker heartbeating, #696, and reverting the changes I recently made for this issue. I didn't realize this issue was specifically regarding getting the status from the worker directly, whereas worker heartbeating queries server on the workers its aware of.

[m1hawkgsm]

Hi, I see that Typescript has this now via the docs, any plans for Python? Also I get the sense the above list is not up to date (seems like TS isn't in TODO, right?), curious to know where we're at.

[cretz]

That is a unique TypeScript feature that has been around far before this issue, but doesn't fully represent what we may want to build. No timeline at this time on when the full feature will be in other SDKs (or the full form in the TypeScript SDK).