per-process-healthchecks

In many modern deployment frameworks there is an expectation that
an application can expose a health-check endpoint so that the binary
status can be monitored. Nova currently does not provide a way to
inspect the health of its binary which complicates cloud monitoring
and maintenance. This blueprint seeks to expose a local health-check
endpoint to address this feature gap.

readonly nova ptg link
https://etherpad.opendev.org/p/r.e70aa851abf8644c29c8abe4bce32b81#L415

    AGREED:

    support http and unix socket in a nova lib

    use cached data for health check

    using time stamp to detect deadlock instead of active probe

    api support /healthcheck, we will debate this in the spec but the http supprot might be enough for that use case

    also this need a spec which i will file, initial implementation will be in nova not a lib.

orginal text at https://etherpad.opendev.org/p/r.e70aa851abf8644c29c8abe4bce32b81#L455