Prometheus options in Substrate relay (#402)

bridges/relays/substrate/Cargo.toml

@@ -12,7 +12,6 @@ codec = { package = "parity-scale-codec", version = "1.3.4" }
 futures = "0.3.5"
 log = "0.4.11"
 paste = "1.0"
-sp-runtime = "2.0"
 structopt = "0.3"
 
 # Bridge dependencies
@@ -24,3 +23,7 @@ relay-millau-client = { path = "../millau-client" }
 relay-rialto-client = { path = "../rialto-client" }
 relay-substrate-client = { path = "../substrate-client" }
 relay-utils = { path = "../utils" }
+
+# Substrate dependencies
+
+sp-runtime = "2.0"

bridges/relays/substrate/src/cli.rs

@@ -27,6 +27,7 @@ pub fn parse_args() -> Command {
 #[derive(StructOpt)]
 #[structopt(about = "Substrate-to-Substrate relay")]
 pub enum Command {
+	/// Relay Millau headers to Rialto.
 	MillauHeadersToRialto {
 		#[structopt(flatten)]
 		millau: MillauConnectionParams,
@@ -34,9 +35,38 @@ pub enum Command {
 		rialto: RialtoConnectionParams,
 		#[structopt(flatten)]
 		rialto_sign: RialtoSigningParams,
+		#[structopt(flatten)]
+		prometheus_params: PrometheusParams,
 	},
 }
 
+/// Prometheus metrics params.
+#[derive(StructOpt)]
+pub struct PrometheusParams {
+	/// Do not expose a Prometheus metric endpoint.
+	#[structopt(long)]
+	pub no_prometheus: bool,
+	/// Expose Prometheus endpoint at given interface.
+	#[structopt(long, default_value = "127.0.0.1")]
+	pub prometheus_host: String,
+	/// Expose Prometheus endpoint at given port.
+	#[structopt(long, default_value = "9616")]
+	pub prometheus_port: u16,
+}
+
+impl From<PrometheusParams> for Option<relay_utils::metrics::MetricsParams> {
+	fn from(cli_params: PrometheusParams) -> Option<relay_utils::metrics::MetricsParams> {
+		if !cli_params.no_prometheus {
+			Some(relay_utils::metrics::MetricsParams {
+				host: cli_params.prometheus_host,
+				port: cli_params.prometheus_port,
+			})
+		} else {
+			None
+		}
+	}
+}
+
 macro_rules! declare_chain_options {
 	($chain:ident, $chain_prefix:ident) => {
 		paste::item! {

bridges/relays/substrate/src/main.rs

@@ -45,6 +45,7 @@ async fn run_command(command: cli::Command) -> Result<(), String> {
 			millau,
 			rialto,
 			rialto_sign,
+			prometheus_params,
 		} => {
 			let millau_client = MillauClient::new(ConnectionParams {
 				host: millau.millau_host,
@@ -61,7 +62,7 @@ async fn run_command(command: cli::Command) -> Result<(), String> {
 				rialto_sign.rialto_signer_password.as_deref(),
 			)
 			.map_err(|e| format!("Failed to parse rialto-signer: {:?}", e))?;
-			millau_headers_to_rialto::run(millau_client, rialto_client, rialto_sign);
+			millau_headers_to_rialto::run(millau_client, rialto_client, rialto_sign, prometheus_params.into());
 		}
 	}
 

bridges/relays/substrate/src/millau_headers_to_rialto.rs

@@ -97,7 +97,12 @@ impl TargetClient<MillauHeadersToRialto> for RialtoTargetClient {
 }
 
 /// Run Millau-to-Rialto headers sync.
-pub fn run(millau_client: MillauClient, rialto_client: RialtoClient, rialto_sign: RialtoSigningParams) {
+pub fn run(
+	millau_client: MillauClient,
+	rialto_client: RialtoClient,
+	rialto_sign: RialtoSigningParams,
+	metrics_params: Option<relay_utils::metrics::MetricsParams>,
+) {
 	let millau_tick = Duration::from_secs(5);
 	let rialto_tick = Duration::from_secs(5);
 	let sync_params = HeadersSyncParams {
@@ -108,7 +113,6 @@ pub fn run(millau_client: MillauClient, rialto_client: RialtoClient, rialto_sign
 		prune_depth: 256,
 		target_tx_mode: TargetTransactionMode::Signed,
 	};
-	let metrics_params = None;
 
 	headers_relay::sync_loop::run(
 		MillauSourceClient::new(millau_client),