Metrics

Raft exports metrics on its internal state via Raft::metrics() -> watch::Receiver<RaftMetrics>.

RaftMetrics contains useful information such as:

• role of this raft node,
• the current leader,
• last, committed, applied log.
• replication state, if this node is a Leader,
• snapshot state,

Metrics can be used as a trigger of application events, as a monitoring data source, etc.

Metrics is not a stream thus it only guarantees to provide the latest state but not every change of the state. Because internally, watch::channel() only stores one state.