Check controller health

The health interface is defined as the following:

health(instance_id: str) -> event_id: str, error_codes: Dict[int, int]

The function returns an event_id and a dictionary mapping worker_id to error_code. A value of 0 indicates a healthy worker, while a non-zero value signals an error.

Example usage:

First, start the lmcache controller at port 9000 and the monitor at port 9001:

PYTHONHASHSEED=123 lmcache_controller --host localhost --port 9000 --monitor-port 9001

Then send a health check request:

curl -X POST http://localhost:9000/health \
  -H "Content-Type: application/json" \
  -d '{"instance_id": "lmcache_default_instance"}'

The controller responds with a message similar to the following:

{"event_id": "health47ce328d-f27e-48ae-ab0c-c2218aabce95", "error_codes": {"0": 0, "1": 0}}

Here error_codes lists each worker’s error_code. 0 represents a healthy worker, while non-zero values indicate an error.