stratus_consensus_is_ready metric is sending both leader and follower labels for leader and primary-follower

[carneiro-cw]

this is probably related to the leadership change

[Thiago316316]

Hi @carneiro-cw ! I'd like to work on this issue.

I dug into the cause: node_mode is read fresh on every metrics call (see the label injection in the gauge/counter/etc. arms of the metrics_impl_fn_inc! macro in metrics_macros.rs), so a role change produces a brand new Prometheus series under the new node_mode label rather than updating the existing one. Since the exporter is built without an idle_timeout in init_metrics_exporter (metrics_config.rs), the old series is never expired — it just sits frozen at its last value, so after a leader/follower swap you end up with both node_mode="leader" and node_mode="follower" reporting simultaneously.

I was able to reproduce this locally by promoting a follower and demoting the previous leader via the stratus_changeToLeader/stratus_changeToFollower admin RPCs and watching /metrics retain both series.

Can I get assigned to this one? I'll open a PR with a proposed fix.