How to manage list of currently active raft-nodes?

[iMashtak]

I am building system that requires to understand which nodes of Raft-cluster is currently down. It doesn't mean I want to remove unreachable nodes from membership, I just want to have some state which will have a list of currently active nodes. It is appropriate that "unreachable" actually would mean "unreachable from leader node" or something like that.

How may I implement this state? I didn't find any callbacks in processing and also didn't find a way to access Raft instance inside RaftNetwork implementation.

[drmingdrmer]

Get RaftMetrics via Raft::metrics() on the leader node.

With OpenRaft 0.9:
In RaftMetrics:
https://docs.rs/openraft/0.9.21/openraft/metrics/struct.RaftMetrics.html

If pub replication: Option<BTreeMap<NID, Option<LogId<NID>>>> lags significantly behind pub last_log_index: Option<u64>, it means replication to this node has issues and the node may be down.

With OpenRaft 0.10, there is another way:
In RaftMetrics:

openraft/openraft/src/metrics/raft_metrics.rs

Lines 107 to 108 in 8cbc7c2

	pub heartbeat: Option<HeartbeatMetrics<C>>,

type HeartbeatMetrics = BTreeMap<NodeIdOf<C>, Option<SerdeInstantOf<C>>> stores the timestamp of the last acknowledgment from a node. If this timestamp is significantly behind the current time, it indicates the node is unreachable.