Broker metrics don't have anything to indicate the health of the broker (to indicate if the broker is active). In Prometheus broker metrics which are used for monitoring, it will be useful if metrics also show the broker health. This way, Prometheus can automatically scrape the broker state and can be used for monitoring purposes. So we need such a metric to capture broker health.
PR: https://github.com/apache/pulsar/issues/20389 Link to discussion: https://lists.apache.org/thread/dmmqo3bnhtr42vt25yph30nxf6cz57pf
