Using-same-fork metric for finality and complex relay (paritytech#1327)

* using_same_fork metric in finality relay

* support `using_different_forks` in messages relay

* added dashboards and alerts

* lockfile

bridges/relays/client-substrate/src/sync_header.rs

@@ -44,7 +44,11 @@ impl<Header> From<Header> for SyncHeader<Header> {
 	}
 }
 
-impl<Header: HeaderT> FinalitySourceHeader<Header::Number> for SyncHeader<Header> {
+impl<Header: HeaderT> FinalitySourceHeader<Header::Hash, Header::Number> for SyncHeader<Header> {
+	fn hash(&self) -> Header::Hash {
+		self.0.hash()
+	}
+
 	fn number(&self) -> Header::Number {
 		*self.0.number()
 	}

bridges/relays/finality/src/finality_loop.rs

@@ -29,7 +29,7 @@ use futures::{select, Future, FutureExt, Stream, StreamExt};
 use num_traits::{One, Saturating};
 use relay_utils::{
 	metrics::MetricsParams, relay_loop::Client as RelayClient, retry_backoff, FailedClient,
-	MaybeConnectionError,
+	HeaderId, MaybeConnectionError,
 };
 use std::{
 	pin::Pin,
@@ -87,7 +87,9 @@ pub trait SourceClient<P: FinalitySyncPipeline>: RelayClient {
 #[async_trait]
 pub trait TargetClient<P: FinalitySyncPipeline>: RelayClient {
 	/// Get best finalized source block number.
-	async fn best_finalized_source_block_number(&self) -> Result<P::Number, Self::Error>;
+	async fn best_finalized_source_block_id(
+		&self,
+	) -> Result<HeaderId<P::Hash, P::Number>, Self::Error>;
 
 	/// Submit header finality proof.
 	async fn submit_finality_proof(
@@ -114,7 +116,11 @@ pub async fn run<P: FinalitySyncPipeline>(
 	let exit_signal = exit_signal.shared();
 	relay_utils::relay_loop(source_client, target_client)
 		.with_metrics(metrics_params)
-		.loop_metric(SyncLoopMetrics::new(Some(&metrics_prefix::<P>()))?)?
+		.loop_metric(SyncLoopMetrics::new(
+			Some(&metrics_prefix::<P>()),
+			"source",
+			"source_at_target",
+		)?)?
 		.expose()
 		.await?
 		.run(metrics_prefix::<P>(), move |source_client, target_client, metrics| {
@@ -169,7 +175,7 @@ where
 
 /// Information about transaction that we have submitted.
 #[derive(Debug, Clone)]
-struct Transaction<Number> {
+pub(crate) struct Transaction<Number> {
 	/// Time when we have submitted this transaction.
 	pub time: Instant,
 	/// The number of the header we have submitted.
@@ -181,7 +187,7 @@ pub(crate) struct RestartableFinalityProofsStream<S> {
 	/// Flag that the stream needs to be restarted.
 	pub(crate) needs_restart: bool,
 	/// The stream itself.
-	stream: Pin<Box<S>>,
+	pub(crate) stream: Pin<Box<S>>,
 }
 
 #[cfg(test)]
@@ -192,15 +198,16 @@ impl<S> From<S> for RestartableFinalityProofsStream<S> {
 }
 
 /// Finality synchronization loop state.
-struct FinalityLoopState<'a, P: FinalitySyncPipeline, FinalityProofsStream> {
+pub(crate) struct FinalityLoopState<'a, P: FinalitySyncPipeline, FinalityProofsStream> {
 	/// Synchronization loop progress.
-	progress: &'a mut (Instant, Option<P::Number>),
+	pub(crate) progress: &'a mut (Instant, Option<P::Number>),
 	/// Finality proofs stream.
-	finality_proofs_stream: &'a mut RestartableFinalityProofsStream<FinalityProofsStream>,
+	pub(crate) finality_proofs_stream:
+		&'a mut RestartableFinalityProofsStream<FinalityProofsStream>,
 	/// Recent finality proofs that we have read from the stream.
-	recent_finality_proofs: &'a mut FinalityProofs<P>,
+	pub(crate) recent_finality_proofs: &'a mut FinalityProofs<P>,
 	/// Last transaction that we have submitted to the target node.
-	last_transaction: Option<Transaction<P::Number>>,
+	pub(crate) last_transaction: Option<Transaction<P::Number>>,
 }
 
 async fn run_until_connection_lost<P: FinalitySyncPipeline>(
@@ -280,7 +287,7 @@ async fn run_until_connection_lost<P: FinalitySyncPipeline>(
 	}
 }
 
-async fn run_loop_iteration<P, SC, TC>(
+pub(crate) async fn run_loop_iteration<P, SC, TC>(
 	source_client: &SC,
 	target_client: &TC,
 	state: FinalityLoopState<'_, P, SC::FinalityProofsStream>,
@@ -295,13 +302,31 @@ where
 	// read best source headers ids from source and target nodes
 	let best_number_at_source =
 		source_client.best_finalized_block_number().await.map_err(Error::Source)?;
-	let best_number_at_target = target_client
-		.best_finalized_source_block_number()
+	let best_id_at_target =
+		target_client.best_finalized_source_block_id().await.map_err(Error::Target)?;
+	let best_number_at_target = best_id_at_target.0;
+
+	let different_hash_at_source = ensure_same_fork::<P, _>(&best_id_at_target, source_client)
 		.await
-		.map_err(Error::Target)?;
+		.map_err(Error::Source)?;
+	let using_same_fork = different_hash_at_source.is_none();
+	if let Some(ref different_hash_at_source) = different_hash_at_source {
+		log::error!(
+			target: "bridge",
+			"Source node ({}) and pallet at target node ({}) have different headers at the same height {:?}: \
+			at-source {:?} vs at-target {:?}",
+			P::SOURCE_NAME,
+			P::TARGET_NAME,
+			best_number_at_target,
+			different_hash_at_source,
+			best_id_at_target.1,
+		);
+	}
+
 	if let Some(ref metrics_sync) = *metrics_sync {
 		metrics_sync.update_best_block_at_source(best_number_at_source);
 		metrics_sync.update_best_block_at_target(best_number_at_target);
+		metrics_sync.update_using_same_fork(using_same_fork);
 	}
 	*state.progress =
 		print_sync_progress::<P>(*state.progress, best_number_at_source, best_number_at_target);
@@ -427,6 +452,22 @@ where
 	Ok(selected_finality_proof)
 }
 
+/// Ensures that both clients are on the same fork.
+///
+/// Returns `Some(_)` with header has at the source client if headers are different.
+async fn ensure_same_fork<P: FinalitySyncPipeline, SC: SourceClient<P>>(
+	best_id_at_target: &HeaderId<P::Hash, P::Number>,
+	source_client: &SC,
+) -> Result<Option<P::Hash>, SC::Error> {
+	let header_at_source = source_client.header_and_finality_proof(best_id_at_target.0).await?.0;
+	let header_hash_at_source = header_at_source.hash();
+	Ok(if best_id_at_target.1 == header_hash_at_source {
+		None
+	} else {
+		Some(header_hash_at_source)
+	})
+}
+
 /// Finality proof that has been selected by the `read_missing_headers` function.
 pub(crate) enum SelectedFinalityProof<Header, FinalityProof> {
 	/// Mandatory header and its proof has been selected. We shall submit proof for this header.