refactor: configure rest sync

- Adds set_chain_source_bitcoind_rest to configure REST synchronization.
- Update docs to reflect the configuration order if REST sync is preferred.
- Simplify the configuration object to capture only REST-related fields.

Author: enigbe

bindings/ldk_node.udl

@@ -34,12 +34,6 @@ dictionary ElectrumSyncConfig {
 	BackgroundSyncConfig? background_sync_config;
 };
 
-[Enum]
-interface BitcoindSyncClientConfig {
-	Rpc();
-	Rest(string rest_host, u16 rest_port);
-};
-
 dictionary LSPS2ServiceConfig {
 	string? require_token;
 	boolean advertise_service;
@@ -83,7 +77,8 @@ interface Builder {
 	void set_entropy_bip39_mnemonic(Mnemonic mnemonic, string? passphrase);
 	void set_chain_source_esplora(string server_url, EsploraSyncConfig? config);
 	void set_chain_source_electrum(string server_url, ElectrumSyncConfig? config);
-	void set_chain_source_bitcoind(string rpc_host, u16 rpc_port, string rpc_user, string rpc_password, BitcoindSyncClientConfig? sync_client_config);
+	void set_chain_source_bitcoind_rpc(string rpc_host, u16 rpc_port, string rpc_user, string rpc_password);
+	void set_chain_source_bitcoind_rest(string rest_host, u16 rest_port);
 	void set_gossip_source_p2p();
 	void set_gossip_source_rgs(string rgs_server_url);
 	void set_liquidity_source_lsps1(PublicKey node_id, SocketAddress address, string? token);

src/builder.rs

@@ -7,7 +7,7 @@
 
 use crate::chain::{ChainSource, DEFAULT_ESPLORA_SERVER_URL};
 use crate::config::{
-	default_user_config, may_announce_channel, AnnounceError, BitcoindSyncClientConfig, Config,
+	default_user_config, may_announce_channel, AnnounceError, BitcoindRestSyncClientConfig, Config,
 	ElectrumSyncConfig, EsploraSyncConfig, DEFAULT_LOG_FILENAME, DEFAULT_LOG_LEVEL,
 	WALLET_KEYS_SEED_LEN,
 };
@@ -96,7 +96,7 @@ enum ChainDataSourceConfig {
 		rpc_port: u16,
 		rpc_user: String,
 		rpc_password: String,
-		sync_client_config: BitcoindSyncClientConfig,
+		sync_client_config: Option<BitcoindRestSyncClientConfig>,
 	},
 }
 
@@ -310,29 +310,70 @@ impl NodeBuilder {
 		self
 	}
 
-	/// Configures the [`Node`] instance to synchronize its chain data from the given Bitcoin Core RPC
-	/// endpoint.
+	/// Configures the [`Node`] instance to connect to a Bitcoin Core node via RPC.
 	///
-	/// This method configures an RPC connection for essential operations, with options for
-	/// synchronization via either RPC (default) or REST.
+	/// This method establishes an RPC connection that enables all essential chain operations including
+	/// transaction broadcasting and chain data synchronization. RPC is the minimum required configuration
+	/// for Bitcoin Core chain interaction and must be set up before any other Bitcoin Core connection options.
 	///
-	/// # Parameters:
-	/// * `rpc_host`, `rpc_port`, `rpc_user`, `rpc_password` - Required parameters for the Bitcoin Core RPC connection
-	/// * `sync_client_config` - Optional synchronization client configuration; defaults to using RPC for sync
-	pub fn set_chain_source_bitcoind(
+	/// ## Parameters:
+	/// * `rpc_host`, `rpc_port`, `rpc_user`, `rpc_password` - Required parameters for the Bitcoin Core RPC
+	///   connection.
+	pub fn set_chain_source_bitcoind_rpc(
 		&mut self, rpc_host: String, rpc_port: u16, rpc_user: String, rpc_password: String,
-		sync_client_config: Option<BitcoindSyncClientConfig>,
 	) -> &mut Self {
 		self.chain_data_source_config = Some(ChainDataSourceConfig::Bitcoind {
 			rpc_host,
 			rpc_port,
 			rpc_user,
 			rpc_password,
-			sync_client_config: sync_client_config.unwrap_or(BitcoindSyncClientConfig::Rpc),
+			sync_client_config: None,
 		});
 		self
 	}
 
+	/// Configures the [`Node`] instance to synchronize chain data from a Bitcoin Core REST endpoint.
+	///
+	/// This method enables chain data synchronization via Bitcoin Core's REST interface.
+	/// It must be called after [`Self::set_chain_source_bitcoind_rpc`] because REST is used only for chain
+	/// synchronization, while RPC is still required for other essential operations like transaction
+	/// broadcasting.
+	///
+	/// ## Parameters:
+	/// * `rest_host`, `rest_port` - Required parameters for the Bitcoin Core REST connection.
+	pub fn set_chain_source_bitcoind_rest(
+		&mut self, rest_host: String, rest_port: u16,
+	) -> &mut Self {
+		let rest_client_config = BitcoindRestSyncClientConfig { rest_host, rest_port };
+
+		match &mut self.chain_data_source_config {
+			Some(ChainDataSourceConfig::Bitcoind {
+				rpc_host,
+				rpc_port,
+				rpc_user,
+				rpc_password,
+				sync_client_config,
+			}) => {
+				if rpc_host.is_empty()
+					|| *rpc_port == 0
+					|| rpc_user.is_empty()
+					|| rpc_password.is_empty()
+				{
+					panic!("RPC configuration is incomplete. Must fully configure via RPC first.");
+				}
+
+				*sync_client_config = Some(rest_client_config);
+			},
+			Some(cs) => {
+				panic!("This option is only valid for ChainSource::Bitcoind. Current chain source config: {cs:?}")
+			},
+			None => {
+				panic!("Must configure via RPC first.")
+			},
+		}
+
+		self
+	}
 	/// Configures the [`Node`] instance to source its gossip data from the Lightning peer-to-peer
 	/// network.
 	pub fn set_gossip_source_p2p(&mut self) -> &mut Self {
@@ -740,21 +781,39 @@ impl ArcedNodeBuilder {
 		self.inner.write().unwrap().set_chain_source_electrum(server_url, sync_config);
 	}
 
-	/// Configures the [`Node`] instance to source its chain data from the given Bitcoin Core RPC
-	/// endpoint.
-	pub fn set_chain_source_bitcoind(
+	/// Configures the [`Node`] instance to connect to a Bitcoin Core node via RPC.
+	///
+	/// This method establishes an RPC connection that enables all essential chain operations including
+	/// transaction broadcasting and chain data synchronization. RPC is the minimum required configuration
+	/// for Bitcoin Core chain interactions and must be set up before any other Bitcoin Core connection options.
+	///
+	/// ## Parameters:
+	/// * `rpc_host`, `rpc_port`, `rpc_user`, `rpc_password` - Required parameters for the Bitcoin Core RPC
+	///   connection.
+	pub fn set_chain_source_bitcoind_rpc(
 		&self, rpc_host: String, rpc_port: u16, rpc_user: String, rpc_password: String,
-		sync_client_config: Option<BitcoindSyncClientConfig>,
 	) {
-		self.inner.write().unwrap().set_chain_source_bitcoind(
+		self.inner.write().unwrap().set_chain_source_bitcoind_rpc(
 			rpc_host,
 			rpc_port,
 			rpc_user,
 			rpc_password,
-			sync_client_config,
 		);
 	}
 
+	/// Configures the [`Node`] instance to synchronize chain data from a Bitcoin Core REST endpoint.
+	///
+	/// This method enables chain data synchronization via Bitcoin Core's REST interface.
+	/// It must be called after [`set_chain_source_bitcoind_rpc`] because REST is used only for chain
+	/// synchronization, while RPC is still required for other essential operations like transaction
+	/// broadcasting.
+	///
+	/// ## Parameters:
+	/// * `rest_host`, `rest_port` - Required parameters for the Bitcoin Core REST connection.
+	pub fn set_chain_source_bitcoind_rest(&self, rest_host: String, rest_port: u16) {
+		self.inner.write().unwrap().set_chain_source_bitcoind_rest(rest_host, rest_port);
+	}
+
 	/// Configures the [`Node`] instance to source its gossip data from the Lightning peer-to-peer
 	/// network.
 	pub fn set_gossip_source_p2p(&self) {

src/chain/mod.rs

@@ -13,8 +13,8 @@ use crate::chain::bitcoind_rpc::{
 };
 use crate::chain::electrum::ElectrumRuntimeClient;
 use crate::config::{
-	BackgroundSyncConfig, BitcoindSyncClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig,
-	BDK_CLIENT_CONCURRENCY, BDK_CLIENT_STOP_GAP, BDK_WALLET_SYNC_TIMEOUT_SECS,
+	BackgroundSyncConfig, BitcoindRestSyncClientConfig, Config, ElectrumSyncConfig,
+	EsploraSyncConfig, BDK_CLIENT_CONCURRENCY, BDK_CLIENT_STOP_GAP, BDK_WALLET_SYNC_TIMEOUT_SECS,
 	FEE_RATE_CACHE_UPDATE_TIMEOUT_SECS, LDK_WALLET_SYNC_TIMEOUT_SECS,
 	RESOLVED_CHANNEL_MONITOR_ARCHIVAL_INTERVAL, TX_BROADCAST_TIMEOUT_SECS,
 	WALLET_SYNC_INTERVAL_MINIMUM_SECS,
@@ -340,7 +340,7 @@ impl ChainSource {
 		host: String, port: u16, rpc_user: String, rpc_password: String,
 		onchain_wallet: Arc<Wallet>, fee_estimator: Arc<OnchainFeeEstimator>,
 		tx_broadcaster: Arc<Broadcaster>, kv_store: Arc<DynStore>, config: Arc<Config>,
-		sync_client_config: BitcoindSyncClientConfig, logger: Arc<Logger>,
+		sync_client_config: Option<BitcoindRestSyncClientConfig>, logger: Arc<Logger>,
 		node_metrics: Arc<RwLock<NodeMetrics>>,
 	) -> Self {
 		let bitcoind_rpc_client = Arc::new(BitcoindRpcClient::new(
@@ -350,15 +350,15 @@ impl ChainSource {
 			rpc_password.clone(),
 		));
 		let bitcoind_sync_client = match sync_client_config {
-			BitcoindSyncClientConfig::Rpc => Arc::new(BitcoindSyncClient::Rpc(RpcClient::new(
-				&rpc_credentials(rpc_user, rpc_password),
-				endpoint(host, port),
-			))),
-			BitcoindSyncClientConfig::Rest { rest_host, rest_port } => {
+			Some(BitcoindRestSyncClientConfig { rest_host, rest_port }) => {
 				Arc::new(BitcoindSyncClient::Rest(RestClient::new(
 					endpoint(rest_host, rest_port).with_path("/rest".to_string()),
 				)))
 			},
+			None => Arc::new(BitcoindSyncClient::Rpc(RpcClient::new(
+				&rpc_credentials(rpc_user, rpc_password),
+				endpoint(host, port),
+			))),
 		};
 
 		let header_cache = tokio::sync::Mutex::new(BoundedHeaderCache::new());

src/config.rs

@@ -397,18 +397,13 @@ impl Default for ElectrumSyncConfig {
 	}
 }
 
-/// Configuration for syncing with Bitcoin Core backend.
+/// Configuration for syncing with Bitcoin Core backend via REST.
 #[derive(Debug, Clone)]
-pub enum BitcoindSyncClientConfig {
-	/// Syncs via RPC.
-	Rpc,
-	/// Syncs via REST.
-	Rest {
-		/// Host URL.
-		rest_host: String,
-		/// Host port.
-		rest_port: u16,
-	},
+pub struct BitcoindRestSyncClientConfig {
+	/// Host URL.
+	pub rest_host: String,
+	/// Host port.
+	pub rest_port: u16,
 }
 
 /// Options which apply on a per-channel basis and may change at runtime or based on negotiation

src/uniffi_types.rs

@@ -11,8 +11,8 @@
 // Make sure to add any re-exported items that need to be used in uniffi below.
 
 pub use crate::config::{
-	default_config, AnchorChannelsConfig, BackgroundSyncConfig, BitcoindSyncClientConfig,
-	ElectrumSyncConfig, EsploraSyncConfig, MaxDustHTLCExposure,
+	default_config, AnchorChannelsConfig, BackgroundSyncConfig, ElectrumSyncConfig,
+	EsploraSyncConfig, MaxDustHTLCExposure,
 };
 pub use crate::graph::{ChannelInfo, ChannelUpdateInfo, NodeAnnouncementInfo, NodeInfo};
 pub use crate::liquidity::{LSPS1OrderStatus, LSPS2ServiceConfig, OnchainPaymentInfo, PaymentInfo};

tests/common/mod.rs

@@ -12,7 +12,7 @@ pub(crate) mod logging;
 
 use logging::TestLogWriter;
 
-use ldk_node::config::{BitcoindSyncClientConfig, Config, ElectrumSyncConfig, EsploraSyncConfig};
+use ldk_node::config::{Config, ElectrumSyncConfig, EsploraSyncConfig};
 use ldk_node::io::sqlite_store::SqliteStore;
 use ldk_node::payment::{PaymentDirection, PaymentKind, PaymentStatus};
 use ldk_node::{
@@ -325,23 +325,19 @@ pub(crate) fn setup_node(
 			let values = bitcoind.params.get_cookie_values().unwrap().unwrap();
 			let rpc_user = values.user;
 			let rpc_password = values.password;
-			builder.set_chain_source_bitcoind(rpc_host, rpc_port, rpc_user, rpc_password, None);
+			builder.set_chain_source_bitcoind_rpc(rpc_host, rpc_port, rpc_user, rpc_password);
 		},
 		TestChainSource::BitcoindRestSync(bitcoind) => {
 			let rpc_host = bitcoind.params.rpc_socket.ip().to_string();
 			let rpc_port = bitcoind.params.rpc_socket.port();
 			let values = bitcoind.params.get_cookie_values().unwrap().unwrap();
 			let rpc_user = values.user;
 			let rpc_password = values.password;
-			let sync_client_config =
-				BitcoindSyncClientConfig::Rest { rest_host: rpc_host.clone(), rest_port: rpc_port };
-			builder.set_chain_source_bitcoind(
-				rpc_host,
-				rpc_port,
-				rpc_user,
-				rpc_password,
-				Some(sync_client_config),
-			);
+			let rest_host = bitcoind.params.rpc_socket.ip().to_string();
+			let rest_port = bitcoind.params.rpc_socket.port();
+			builder
+				.set_chain_source_bitcoind_rpc(rpc_host, rpc_port, rpc_user, rpc_password)
+				.set_chain_source_bitcoind_rest(rest_host, rest_port);
 		},
 	}