feat: Feat/add on rpc server started hook (#4947)

Co-authored-by: Matthias Seitz <matthias.seitz@outlook.de>

bin/reth/Cargo.toml

@@ -37,7 +37,7 @@ reth-rpc-builder = { path = "../../crates/rpc/rpc-builder" }
 reth-rpc = { path = "../../crates/rpc/rpc" }
 reth-rpc-types = { path = "../../crates/rpc/rpc-types" }
 reth-rpc-types-compat = { path = "../../crates/rpc/rpc-types-compat" }
-reth-rpc-api = { path = "../../crates/rpc/rpc-api" }
+reth-rpc-api = { path = "../../crates/rpc/rpc-api", features = ["client"] }
 reth-network = { path = "../../crates/net/network", features = ["serde"] }
 reth-network-api.workspace = true
 reth-downloaders = { path = "../../crates/net/downloaders", features = ["test-utils"] }

bin/reth/src/args/rpc_server_args.rs

@@ -3,7 +3,7 @@
 use crate::{
     args::GasPriceOracleArgs,
     cli::{
-        components::{RethNodeComponents, RethRpcComponents},
+        components::{RethNodeComponents, RethRpcComponents, RethRpcServerHandles},
         config::RethRpcConfig,
         ext::RethNodeCommandConfig,
     },
@@ -184,7 +184,7 @@ impl RpcServerArgs {
         engine_api: Engine,
         jwt_secret: JwtSecret,
         conf: &mut Conf,
-    ) -> eyre::Result<(RpcServerHandle, AuthServerHandle)>
+    ) -> eyre::Result<RethRpcServerHandles>
     where
         Reth: RethNodeComponents,
         Engine: EngineApiServer,
@@ -202,12 +202,13 @@ impl RpcServerArgs {
             .with_events(components.events())
             .with_executor(components.task_executor())
             .build_with_auth_server(module_config, engine_api);
-        let node_modules = RethRpcComponents { registry: &mut registry, modules: &mut modules };
+
+        let rpc_components = RethRpcComponents { registry: &mut registry, modules: &mut modules };
         // apply configured customization
-        conf.extend_rpc_modules(self, components, node_modules)?;
+        conf.extend_rpc_modules(self, components, rpc_components)?;
 
         let server_config = self.rpc_server_config();
-        let launch_rpc = modules.start_server(server_config).map_ok(|handle| {
+        let launch_rpc = modules.clone().start_server(server_config).map_ok(|handle| {
             if let Some(url) = handle.ipc_endpoint() {
                 info!(target: "reth::cli", url=%url, "RPC IPC server started");
             }
@@ -227,7 +228,14 @@ impl RpcServerArgs {
         });
 
         // launch servers concurrently
-        Ok(futures::future::try_join(launch_rpc, launch_auth).await?)
+        let (rpc, auth) = futures::future::try_join(launch_rpc, launch_auth).await?;
+        let handles = RethRpcServerHandles { rpc, auth };
+
+        // call hook
+        let rpc_components = RethRpcComponents { registry: &mut registry, modules: &mut modules };
+        conf.on_rpc_server_started(self, components, rpc_components, handles.clone())?;
+
+        Ok(handles)
     }
 
     /// Convenience function for starting a rpc server with configs which extracted from cli args.

bin/reth/src/cli/components.rs

@@ -6,7 +6,9 @@ use reth_provider::{
     AccountReader, BlockReaderIdExt, CanonStateSubscriptions, ChainSpecProvider, ChangeSetReader,
     EvmEnvProvider, StateProviderFactory,
 };
-use reth_rpc_builder::{RethModuleRegistry, TransportRpcModules};
+use reth_rpc_builder::{
+    auth::AuthServerHandle, RethModuleRegistry, RpcServerHandle, TransportRpcModules,
+};
 use reth_tasks::TaskSpawner;
 use reth_transaction_pool::TransactionPool;
 use std::sync::Arc;
@@ -143,3 +145,25 @@ where
         self.events.clone()
     }
 }
+
+/// Contains the handles to the spawned RPC servers.
+///
+/// This can be used to access the endpoints of the servers.
+///
+/// # Example
+///
+/// ```rust
+/// use reth::cli::components::RethRpcServerHandles;
+/// use reth::rpc::api::EthApiClient;
+/// # async fn t(handles: RethRpcServerHandles) {
+///    let client = handles.rpc.http_client().expect("http server not started");
+///    let block_number = client.block_number().await.unwrap();
+/// # }
+/// ```
+#[derive(Debug, Clone)]
+pub struct RethRpcServerHandles {
+    /// The regular RPC server handle.
+    pub rpc: RpcServerHandle,
+    /// The handle to the auth server (engine API)
+    pub auth: AuthServerHandle,
+}

bin/reth/src/cli/ext.rs

@@ -10,6 +10,8 @@ use reth_payload_builder::{PayloadBuilderHandle, PayloadBuilderService};
 use reth_tasks::TaskSpawner;
 use std::{fmt, marker::PhantomData};
 
+use crate::cli::components::RethRpcServerHandles;
+
 /// A trait that allows for extending parts of the CLI with additional functionality.
 ///
 /// This is intended as a way to allow to _extend_ the node command. For example, to register
@@ -46,6 +48,25 @@ pub trait RethNodeCommandConfig: fmt::Debug {
         Ok(())
     }
 
+    /// Event hook called once the rpc servers has been started.
+    fn on_rpc_server_started<Conf, Reth>(
+        &mut self,
+        config: &Conf,
+        components: &Reth,
+        rpc_components: RethRpcComponents<'_, Reth>,
+        handles: RethRpcServerHandles,
+    ) -> eyre::Result<()>
+    where
+        Conf: RethRpcConfig,
+        Reth: RethNodeComponents,
+    {
+        let _ = config;
+        let _ = components;
+        let _ = rpc_components;
+        let _ = handles;
+        Ok(())
+    }
+
     /// Allows for registering additional RPC modules for the transports.
     ///
     /// This is expected to call the merge functions of [reth_rpc_builder::TransportRpcModules], for
@@ -190,6 +211,24 @@ impl<T: RethNodeCommandConfig> RethNodeCommandConfig for NoArgs<T> {
         }
     }
 
+    fn on_rpc_server_started<Conf, Reth>(
+        &mut self,
+        config: &Conf,
+        components: &Reth,
+        rpc_components: RethRpcComponents<'_, Reth>,
+        handles: RethRpcServerHandles,
+    ) -> eyre::Result<()>
+    where
+        Conf: RethRpcConfig,
+        Reth: RethNodeComponents,
+    {
+        if let Some(conf) = self.inner_mut() {
+            conf.on_rpc_server_started(config, components, rpc_components, handles)
+        } else {
+            Ok(())
+        }
+    }
+
     fn extend_rpc_modules<Conf, Reth>(
         &mut self,
         config: &Conf,

bin/reth/src/node/mod.rs

@@ -533,7 +533,7 @@ impl<Ext: RethCliExt> NodeCommand<Ext> {
         self.adjust_instance_ports();
 
         // Start RPC servers
-        let (_rpc_server, _auth_server) =
+        let _rpc_server_handles =
             self.rpc.start_servers(&components, engine_api, jwt_secret, &mut self.ext).await?;
 
         // Run consensus engine to completion

crates/rpc/rpc-builder/src/lib.rs

@@ -1478,7 +1478,7 @@ impl TransportRpcModuleConfig {
 }
 
 /// Holds installed modules per transport type.
-#[derive(Debug, Default)]
+#[derive(Debug, Clone, Default)]
 pub struct TransportRpcModules<Context = ()> {
     /// The original config
     config: TransportRpcModuleConfig,