Relay dashboard (#191)

* expose metrics for Prometheus

* added preconfigured configs for Prometheus and Grafana

* metrics-related cli args

* fix compilation

bridges/relays/ethereum/src/ethereum_sync_loop.rs

@@ -18,6 +18,7 @@
 
 use crate::ethereum_client::{EthereumConnectionParams, EthereumHighLevelRpc, EthereumRpcClient};
 use crate::ethereum_types::{EthereumHeaderId, EthereumHeadersSyncPipeline, Header, QueuedEthereumHeader, Receipt};
+use crate::metrics::MetricsParams;
 use crate::rpc::{EthereumRpc, SubstrateRpc};
 use crate::rpc_errors::RpcError;
 use crate::substrate_client::{
@@ -61,6 +62,8 @@ pub struct EthereumSyncParams {
 	pub sub_sign: SubstrateSigningParams,
 	/// Synchronization parameters.
 	pub sync_params: HeadersSyncParams,
+	/// Metrics parameters.
+	pub metrics_params: Option<MetricsParams>,
 }
 
 impl Default for EthereumSyncParams {
@@ -77,6 +80,7 @@ impl Default for EthereumSyncParams {
 				prune_depth: PRUNE_DEPTH,
 				target_tx_mode: TargetTransactionMode::Signed,
 			},
+			metrics_params: Some(Default::default()),
 		}
 	}
 }
@@ -204,6 +208,7 @@ pub fn run(params: EthereumSyncParams) -> Result<(), RpcError> {
 		target,
 		SUBSTRATE_TICK_INTERVAL,
 		params.sync_params,
+		params.metrics_params,
 		futures::future::pending(),
 	);