Health Check Service

[bbengfort]

Implement a health check service that routinely loops through verified VASPs and performs a health check if the VASP implements the TRISAHealth Service. Note that mTLS may be required to connect to the status endpoint and also note that the status endpoint is optional, so expect or handle Unavailable or NotImplemented codes.

When sending health checks, the directory service should be polite, and notify the node the number of failed attempts prior to this check and the last time the check occurred. The node may return rate limiting/accelerating information using not before and not after, which the directory service should also respect.

The health check service should store the last known service state with the VASP and any health check metadata (e.g. next time to check, number of attempts in the GDSExtra protocol buffer).

No historical or timeseries data is required, in the future, this information will be posted to Prometheus.