Add node authority status metric

node/network/gossip-support/src/lib.rs

@@ -57,6 +57,10 @@ use polkadot_primitives::v1::{AuthorityDiscoveryId, Hash, SessionIndex};
 #[cfg(test)]
 mod tests;
 
+mod metrics;
+
+use metrics::Metrics;
+
 const LOG_TARGET: &str = "parachain::gossip-support";
 // How much time should we wait to reissue a connection request
 // since the last authority discovery resolution failure.
@@ -104,14 +108,20 @@ pub struct GossipSupport<AD> {
 	connected_authorities_by_peer_id: HashMap<PeerId, HashSet<AuthorityDiscoveryId>>,
 	/// Authority discovery service.
 	authority_discovery: AD,
+
+	/// Subsystem metrics.
+	metrics: Metrics,
 }
 
 impl<AD> GossipSupport<AD>
 where
 	AD: AuthorityDiscovery,
 {
 	/// Create a new instance of the [`GossipSupport`] subsystem.
-	pub fn new(keystore: SyncCryptoStorePtr, authority_discovery: AD) -> Self {
+	pub fn new(keystore: SyncCryptoStorePtr, authority_discovery: AD, metrics: Metrics) -> Self {
+		// Initialize the `polkadot_node_is_authority` metric.
+		metrics.on_is_not_authority();
+
 		Self {
 			keystore,
 			last_session_index: None,
@@ -121,6 +131,7 @@ where
 			connected_authorities: HashMap::new(),
 			connected_authorities_by_peer_id: HashMap::new(),
 			authority_discovery,
+			metrics,
 		}
 	}
 
@@ -212,7 +223,14 @@ where
 				}
 
 				let all_authorities = determine_relevant_authorities(ctx, relay_parent).await?;
-				let our_index = ensure_i_am_an_authority(&self.keystore, &all_authorities).await?;
+				let our_index = ensure_i_am_an_authority(&self.keystore, &all_authorities)
+					.await
+					.map_err(|e| {
+						self.metrics.on_is_not_authority();
+						e
+					})?;
+				self.metrics.on_is_authority();
+
 				let other_authorities = {
 					let mut authorities = all_authorities.clone();
 					authorities.swap_remove(our_index);

node/network/gossip-support/src/metrics.rs

@@ -0,0 +1,67 @@
+// Copyright 2021 Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+use polkadot_node_subsystem_util::{
+	metrics,
+	metrics::{
+		prometheus,
+		prometheus::{Gauge, PrometheusError, Registry, U64},
+	},
+};
+
+/// Dispute Distribution metrics.
+#[derive(Clone, Default)]
+pub struct Metrics(Option<MetricsInner>);
+
+#[derive(Clone)]
+struct MetricsInner {
+	/// Tracks authority status.
+	is_authority: Gauge<U64>,
+}
+
+impl Metrics {
+	#[cfg(test)]
+	/// Dummy constructor for testing.
+	pub fn new_dummy() -> Self {
+		Self(None)
+	}
+
+	/// Set the authority flag.
+	pub fn on_is_authority(&self) {
+		if let Some(metrics) = &self.0 {
+			metrics.is_authority.set(1);
+		}
+	}
+
+	/// Unset the authority flag.
+	pub fn on_is_not_authority(&self) {
+		if let Some(metrics) = &self.0 {
+			metrics.is_authority.set(0);
+		}
+	}
+}
+
+impl metrics::Metrics for Metrics {
+	fn try_register(registry: &Registry) -> Result<Self, PrometheusError> {
+		let metrics = MetricsInner {
+			is_authority: prometheus::register(
+				Gauge::new("polkadot_node_is_authority", "Tracks the node authority status.")?,
+				registry,
+			)?,
+		};
+		Ok(Metrics(Some(metrics)))
+	}
+}

node/network/gossip-support/src/tests.rs

@@ -126,7 +126,11 @@ async fn get_other_authorities_addrs_map() -> HashMap<AuthorityDiscoveryId, Hash
 }
 
 fn make_subsystem() -> GossipSupport<MockAuthorityDiscovery> {
-	GossipSupport::new(make_ferdie_keystore(), MOCK_AUTHORITY_DISCOVERY.clone())
+	GossipSupport::new(
+		make_ferdie_keystore(),
+		MOCK_AUTHORITY_DISCOVERY.clone(),
+		Metrics::new_dummy(),
+	)
 }
 
 fn test_harness<T: Future<Output = VirtualOverseer>, AD: AuthorityDiscovery>(

node/service/src/overseer.rs

@@ -264,6 +264,7 @@ where
 		.gossip_support(GossipSupportSubsystem::new(
 			keystore.clone(),
 			authority_discovery_service.clone(),
+			Metrics::register(registry)?,
 		))
 		.dispute_coordinator(if disputes_enabled {
 			DisputeCoordinatorSubsystem::new(