feat: add prometheus support (#474)

bin/reth/Cargo.toml

@@ -38,3 +38,5 @@ serde = "1.0"
 serde_json = "1.0"
 walkdir = "2.3"
 futures = "0.3.25"
+metrics-exporter-prometheus = { version = "0.11.0", features = ["http-listener"] }
+metrics-util = "0.14.0"

bin/reth/src/cli.rs

@@ -1,6 +1,8 @@
 //! CLI definition and entrypoint to executable
 
 use clap::{ArgAction, Parser, Subcommand};
+use metrics_exporter_prometheus::PrometheusBuilder;
+use metrics_util::layers::{PrefixLayer, Stack};
 use tracing_subscriber::util::SubscriberInitExt;
 
 use crate::{
@@ -16,6 +18,16 @@ pub async fn run() -> eyre::Result<()> {
 
     reth_tracing::build_subscriber(tracing).init();
 
+    if opt.metrics {
+        let (recorder, exporter) =
+            PrometheusBuilder::new().build().expect("couldn't build Prometheus");
+        tokio::task::spawn(exporter);
+        Stack::new(recorder)
+            .push(PrefixLayer::new("reth"))
+            .install()
+            .expect("couldn't install metrics recorder");
+    }
+
     match opt.command {
         Commands::Node(command) => command.execute().await,
         Commands::TestEthChain(command) => command.execute().await,
@@ -51,4 +63,7 @@ struct Cli {
     /// Silence all output
     #[clap(long, global = true)]
     silent: bool,
+
+    #[clap(long, global = true)]
+    metrics: bool,
 }

crates/net/eth-wire/Cargo.toml

@@ -27,6 +27,7 @@ pin-project = "1.0"
 tracing = "0.1.37"
 snap = "1.0.5"
 smol_str = { version = "0.1", features = ["serde"] }
+metrics = "0.20.1"
 
 [dev-dependencies]
 test-fuzz = "3.0.4"

crates/net/eth-wire/src/p2pstream.rs

@@ -7,6 +7,7 @@ use crate::{
 };
 use bytes::{Buf, Bytes, BytesMut};
 use futures::{Sink, SinkExt, StreamExt};
+use metrics::counter;
 use pin_project::pin_project;
 use reth_rlp::{Decodable, DecodeError, Encodable, EMPTY_STRING_CODE};
 use serde::{Deserialize, Serialize};
@@ -119,6 +120,7 @@ where
                 let reason = DisconnectReason::try_from(disconnect_id)?;
 
                 tracing::error!("Disconnected by peer during handshake: {}", reason);
+                counter!("p2pstream.disconnected_errors", 1);
                 return Err(P2PStreamError::HandshakeError(P2PHandshakeError::Disconnected(reason)))
             }
             id => {