Introduce telemetry for observability

e2e-tests/src/lib.rs

@@ -140,6 +140,10 @@ max_client_to_self_delay = 1024
 min_payment_size_msat = 0
 max_payment_size_msat = 1000000000
 client_trusts_lsp = true
+
+[metrics]
+enabled = true
+poll_metrics_interval = 1
 "#,
 			storage_dir = storage_dir.display(),
 		);

e2e-tests/tests/e2e.rs

@@ -827,3 +827,95 @@ async fn test_hodl_invoice_fail() {
 		events_a.iter().map(|e| &e.event).collect::<Vec<_>>()
 	);
 }
+
+#[tokio::test]
+async fn test_metrics_endpoint() {
+	let bitcoind = TestBitcoind::new();
+
+	// Test with metrics enabled
+	let server_a = LdkServerHandle::start(&bitcoind).await;
+	let server_b = LdkServerHandle::start(&bitcoind).await;
+
+	let client = server_a.client();
+	let metrics_result = client.get_metrics().await;
+
+	assert!(metrics_result.is_ok(), "Expected metrics to succeed when enabled");
+	let metrics = metrics_result.unwrap();
+
+	// Verify initial state
+	assert!(metrics.contains("ldk_server_total_peers_count 0"));
+	assert!(metrics.contains("ldk_server_total_payments_count 0"));
+	assert!(metrics.contains("ldk_server_total_successful_payments_count 0"));
+	assert!(metrics.contains("ldk_server_total_pending_payments_count 0"));
+	assert!(metrics.contains("ldk_server_total_failed_payments_count 0"));
+	assert!(metrics.contains("ldk_server_total_channels_count 0"));
+	assert!(metrics.contains("ldk_server_total_public_channels_count 0"));
+	assert!(metrics.contains("ldk_server_total_private_channels_count 0"));
+	assert!(metrics.contains("ldk_server_total_onchain_balance_sats 0"));
+	assert!(metrics.contains("ldk_server_spendable_onchain_balance_sats 0"));
+	assert!(metrics.contains("ldk_server_total_anchor_channels_reserve_sats 0"));
+	assert!(metrics.contains("ldk_server_total_lightning_balance_sats 0"));
+
+	// Set up channel and make a payment to trigger metrics update
+	setup_funded_channel(&bitcoind, &server_a, &server_b, 100_000).await;
+
+	// Poll for channel, peer and balance metrics.
+	let timeout = Duration::from_secs(10);
+	let start = std::time::Instant::now();
+	loop {
+		let metrics = client.get_metrics().await.unwrap();
+		if metrics.contains("ldk_server_total_peers_count 1")
+			&& metrics.contains("ldk_server_total_channels_count 1")
+			&& metrics.contains("ldk_server_total_public_channels_count 1")
+			&& metrics.contains("ldk_server_total_payments_count 2")
+			&& !metrics.contains("ldk_server_total_lightning_balance_sats 0")
+			&& !metrics.contains("ldk_server_total_onchain_balance_sats 0")
+			&& !metrics.contains("ldk_server_spendable_onchain_balance_sats 0")
+			&& !metrics.contains("ldk_server_total_anchor_channels_reserve_sats 0")
+		{
+			break;
+		}
+
+		if start.elapsed() > timeout {
+			let current_metrics = client.get_metrics().await.unwrap();
+			panic!(
+				"Timed out waiting for channel, peer and balance metrics to update. Current metrics:\n{}",
+				current_metrics
+			);
+		}
+		tokio::time::sleep(Duration::from_secs(1)).await;
+	}
+
+	let invoice_resp = server_b
+		.client()
+		.bolt11_receive(Bolt11ReceiveRequest {
+			amount_msat: Some(10_000_000),
+			description: Some(Bolt11InvoiceDescription {
+				kind: Some(bolt11_invoice_description::Kind::Direct("metrics test".to_string())),
+			}),
+			expiry_secs: 3600,
+		})
+		.await
+		.unwrap();
+
+	run_cli(&server_a, &["bolt11-send", &invoice_resp.invoice]);
+
+	// Wait to receive the PaymentSuccessful event and update metrics
+	let timeout = Duration::from_secs(30);
+	let start = std::time::Instant::now();
+	loop {
+		let metrics = client.get_metrics().await.unwrap();
+		if metrics.contains("ldk_server_total_successful_payments_count 1")
+			&& !metrics.contains("ldk_server_total_lightning_balance_sats 0")
+			&& !metrics.contains("ldk_server_total_onchain_balance_sats 0")
+			&& !metrics.contains("ldk_server_spendable_onchain_balance_sats 0")
+			&& !metrics.contains("ldk_server_total_anchor_channels_reserve_sats 0")
+		{
+			break;
+		}
+		if start.elapsed() > timeout {
+			panic!("Timed out waiting for payment metrics to update");
+		}
+		tokio::time::sleep(Duration::from_millis(500)).await;
+	}
+}

ldk-server-client/src/client.rs

@@ -38,14 +38,15 @@ use ldk_server_protos::endpoints::{
 	BOLT11_RECEIVE_PATH, BOLT11_RECEIVE_VARIABLE_AMOUNT_VIA_JIT_CHANNEL_PATH,
 	BOLT11_RECEIVE_VIA_JIT_CHANNEL_PATH, BOLT11_SEND_PATH, BOLT12_RECEIVE_PATH, BOLT12_SEND_PATH,
 	CLOSE_CHANNEL_PATH, CONNECT_PEER_PATH, DISCONNECT_PEER_PATH, EXPORT_PATHFINDING_SCORES_PATH,
-	FORCE_CLOSE_CHANNEL_PATH, GET_BALANCES_PATH, GET_NODE_INFO_PATH, GET_PAYMENT_DETAILS_PATH,
-	GRAPH_GET_CHANNEL_PATH, GRAPH_GET_NODE_PATH, GRAPH_LIST_CHANNELS_PATH, GRAPH_LIST_NODES_PATH,
-	LIST_CHANNELS_PATH, LIST_FORWARDED_PAYMENTS_PATH, LIST_PAYMENTS_PATH, LIST_PEERS_PATH,
-	ONCHAIN_RECEIVE_PATH, ONCHAIN_SEND_PATH, OPEN_CHANNEL_PATH, SIGN_MESSAGE_PATH, SPLICE_IN_PATH,
-	SPLICE_OUT_PATH, SPONTANEOUS_SEND_PATH, UNIFIED_SEND_PATH, UPDATE_CHANNEL_CONFIG_PATH,
-	VERIFY_SIGNATURE_PATH,
+	FORCE_CLOSE_CHANNEL_PATH, GET_BALANCES_PATH, GET_METRICS_PATH, GET_NODE_INFO_PATH,
+	GET_PAYMENT_DETAILS_PATH, GRAPH_GET_CHANNEL_PATH, GRAPH_GET_NODE_PATH,
+	GRAPH_LIST_CHANNELS_PATH, GRAPH_LIST_NODES_PATH, LIST_CHANNELS_PATH,
+	LIST_FORWARDED_PAYMENTS_PATH, LIST_PAYMENTS_PATH, LIST_PEERS_PATH, ONCHAIN_RECEIVE_PATH,
+	ONCHAIN_SEND_PATH, OPEN_CHANNEL_PATH, SIGN_MESSAGE_PATH, SPLICE_IN_PATH, SPLICE_OUT_PATH,
+	SPONTANEOUS_SEND_PATH, UNIFIED_SEND_PATH, UPDATE_CHANNEL_CONFIG_PATH, VERIFY_SIGNATURE_PATH,
 };
 use ldk_server_protos::error::{ErrorCode, ErrorResponse};
+use prost::bytes::Bytes;
 use prost::Message;
 use reqwest::header::CONTENT_TYPE;
 use reqwest::{Certificate, Client};
@@ -69,6 +70,11 @@ pub struct LdkServerClient {
 	api_key: String,
 }
 
+enum RequestType {
+	Get,
+	Post,
+}
+
 impl LdkServerClient {
 	/// Constructs a [`LdkServerClient`] using `base_url` as the ldk-server endpoint.
 	///
@@ -114,6 +120,18 @@ impl LdkServerClient {
 		self.post_request(&request, &url).await
 	}
 
+	/// Retrieve the node metrics in Prometheus format.
+	pub async fn get_metrics(&self) -> Result<String, LdkServerError> {
+		let url = format!("https://{}/{GET_METRICS_PATH}", self.base_url);
+		let payload = self.make_request(&url, RequestType::Get, None, false).await?;
+		String::from_utf8(payload.to_vec()).map_err(|e| {
+			LdkServerError::new(
+				InternalError,
+				format!("Failed to decode metrics response as string: {}", e),
+			)
+		})
+	}
+
 	/// Retrieves an overview of all known balances.
 	/// For API contract/usage, refer to docs for [`GetBalancesRequest`] and [`GetBalancesResponse`].
 	pub async fn get_balances(
@@ -431,31 +449,45 @@ impl LdkServerClient {
 		&self, request: &Rq, url: &str,
 	) -> Result<Rs, LdkServerError> {
 		let request_body = request.encode_to_vec();
-		let auth_header = self.compute_auth_header(&request_body);
-		let response_raw = self
-			.client
-			.post(url)
-			.header(CONTENT_TYPE, APPLICATION_OCTET_STREAM)
-			.header("X-Auth", auth_header)
-			.body(request_body)
-			.send()
-			.await
-			.map_err(|e| {
-				LdkServerError::new(InternalError, format!("HTTP request failed: {}", e))
-			})?;
+		let payload = self.make_request(url, RequestType::Post, Some(request_body), true).await?;
+		Rs::decode(&payload[..]).map_err(|e| {
+			LdkServerError::new(InternalError, format!("Failed to decode success response: {}", e))
+		})
+	}
+
+	async fn make_request(
+		&self, url: &str, request_type: RequestType, body: Option<Vec<u8>>, authenticated: bool,
+	) -> Result<Bytes, LdkServerError> {
+		let builder = match request_type {
+			RequestType::Get => self.client.get(url),
+			RequestType::Post => self.client.post(url),
+		};
+
+		let builder = if authenticated {
+			let body_for_auth = body.as_deref().unwrap_or(&[]);
+			let auth_header = self.compute_auth_header(body_for_auth);
+			builder.header("X-Auth", auth_header)
+		} else {
+			builder
+		};
+
+		let builder = if let Some(body_content) = body {
+			builder.header(CONTENT_TYPE, APPLICATION_OCTET_STREAM).body(body_content)
+		} else {
+			builder
+		};
+
+		let response_raw = builder.send().await.map_err(|e| {
+			LdkServerError::new(InternalError, format!("HTTP request failed: {}", e))
+		})?;
 
 		let status = response_raw.status();
 		let payload = response_raw.bytes().await.map_err(|e| {
 			LdkServerError::new(InternalError, format!("Failed to read response body: {}", e))
 		})?;
 
 		if status.is_success() {
-			Ok(Rs::decode(&payload[..]).map_err(|e| {
-				LdkServerError::new(
-					InternalError,
-					format!("Failed to decode success response: {}", e),
-				)
-			})?)
+			Ok(payload)
 		} else {
 			let error_response = ErrorResponse::decode(&payload[..]).map_err(|e| {
 				LdkServerError::new(

ldk-server-protos/src/endpoints.rs

@@ -43,3 +43,4 @@ pub const GRAPH_LIST_CHANNELS_PATH: &str = "GraphListChannels";
 pub const GRAPH_GET_CHANNEL_PATH: &str = "GraphGetChannel";
 pub const GRAPH_LIST_NODES_PATH: &str = "GraphListNodes";
 pub const GRAPH_GET_NODE_PATH: &str = "GraphGetNode";
+pub const GET_METRICS_PATH: &str = "metrics";

ldk-server/ldk-server-config.toml

@@ -88,3 +88,8 @@ client_trusts_lsp = false
 ## A token we may require to be sent by the clients.
 ## If set, only requests matching this token will be accepted. (uncomment and set if required)
 # require_token = ""
+
+# Metrics settings
+[metrics]
+enabled = false
+poll_metrics_interval = 60       # The polling interval for metrics in seconds. Defaults to 60secs if unset and metrics enabled.

ldk-server/src/main.rs

@@ -16,7 +16,7 @@ use std::fs;
 use std::os::unix::fs::PermissionsExt;
 use std::path::{Path, PathBuf};
 use std::sync::Arc;
-use std::time::{SystemTime, UNIX_EPOCH};
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 use clap::Parser;
 use hex::DisplayHex;
@@ -50,6 +50,7 @@ use crate::io::persist::{
 use crate::service::NodeService;
 use crate::util::config::{load_config, ArgsConfig, ChainSource};
 use crate::util::logger::ServerLogger;
+use crate::util::metrics::Metrics;
 use crate::util::proto_adapter::{forwarded_payment_to_proto, payment_to_proto};
 use crate::util::systemd;
 use crate::util::tls::get_or_generate_tls_config;
@@ -273,6 +274,28 @@ fn main() {
 			}
 		};
 		let event_node = Arc::clone(&node);
+
+		let metrics: Option<Arc<Metrics>> = if config_file.metrics_enabled {
+			let poll_metrics_interval = Duration::from_secs(config_file.poll_metrics_interval.unwrap_or(60));
+			let metrics_node = Arc::clone(&node);
+			let mut interval = tokio::time::interval(poll_metrics_interval);
+			let metrics = Arc::new(Metrics::new());
+			let metrics_bg = Arc::clone(&metrics);
+
+			// Initialize metrics that are event-driven to ensure they start with correct values from persistence
+			metrics.initialize_payment_metrics(&metrics_node);
+
+			runtime.spawn(async move {
+				loop {
+					interval.tick().await;
+					metrics_bg.update_all_pollable_metrics(&metrics_node);
+				}
+			});
+			Some(metrics)
+		} else {
+			None
+		};
+
 		let rest_svc_listener = TcpListener::bind(config_file.rest_service_addr)
 			.await
 			.expect("Failed to bind listening port");
@@ -313,7 +336,24 @@ fn main() {
 							if let Err(e) = event_node.event_handled() {
 								error!("Failed to mark event as handled: {e}");
 							}
+
+							if let Some(metrics) = &metrics {
+								metrics.update_channels_count(false);
+							}
 						},
+						Event::ChannelClosed { channel_id, counterparty_node_id, .. } => {
+							info!(
+								"CHANNEL_CLOSED: {} from counterparty {:?}",
+								channel_id, counterparty_node_id
+							);
+							if let Err(e) = event_node.event_handled() {
+								error!("Failed to mark event as handled: {e}");
+							}
+
+							if let Some(metrics) = &metrics {
+								metrics.update_channels_count(true);
+							}
+						}
 						Event::PaymentReceived { payment_id, payment_hash, amount_msat, .. } => {
 							info!(
 								"PAYMENT_RECEIVED: with id {:?}, hash {}, amount_msat {}",
@@ -328,6 +368,10 @@ fn main() {
 								&event_node,
 								Arc::clone(&event_publisher),
 								Arc::clone(&paginated_store)).await;
+
+							if let Some(metrics) = &metrics {
+								metrics.update_all_balances(&event_node);
+							}
 						},
 						Event::PaymentSuccessful {payment_id, ..} => {
 							let payment_id = payment_id.expect("PaymentId expected for ldk-server >=0.1");
@@ -339,6 +383,11 @@ fn main() {
 								&event_node,
 								Arc::clone(&event_publisher),
 								Arc::clone(&paginated_store)).await;
+
+							if let Some(metrics) = &metrics {
+								metrics.update_payments_count(true);
+								metrics.update_all_balances(&event_node);
+							}
 						},
 						Event::PaymentFailed {payment_id, ..} => {
 							let payment_id = payment_id.expect("PaymentId expected for ldk-server >=0.1");
@@ -350,6 +399,10 @@ fn main() {
 								&event_node,
 								Arc::clone(&event_publisher),
 								Arc::clone(&paginated_store)).await;
+
+							if let Some(metrics) = &metrics {
+								metrics.update_payments_count(false);
+							}
 						},
 						Event::PaymentClaimable {payment_id, ..} => {
 							publish_event_and_upsert_payment(&payment_id,
@@ -435,7 +488,7 @@ fn main() {
 				res = rest_svc_listener.accept() => {
 					match res {
 						Ok((stream, _)) => {
-							let node_service = NodeService::new(Arc::clone(&node), Arc::clone(&paginated_store), api_key.clone());
+							let node_service = NodeService::new(Arc::clone(&node), Arc::clone(&paginated_store), api_key.clone(), metrics.clone());
 							let acceptor = tls_acceptor.clone();
 							runtime.spawn(async move {
 								match acceptor.accept(stream).await {