Expose GRANDPA RPC API from Millau node (#408)

* expose GRANDPA RPC API from Millau node

* fmt

bridges/bin/millau/node/Cargo.toml

@@ -28,6 +28,7 @@ sc-consensus = "0.8"
 sc-consensus-aura = "0.8"
 sc-executor = "0.8"
 sc-finality-grandpa = "0.8"
+sc-finality-grandpa-rpc = "0.8"
 sc-service = "0.8"
 sc-rpc = "2.0"
 sc-transaction-pool = "2.0"

bridges/bin/millau/node/src/service.rs

@@ -33,6 +33,7 @@ use sc_client_api::{ExecutorProvider, RemoteBackend};
 use sc_executor::native_executor_instance;
 pub use sc_executor::NativeExecutor;
 use sc_finality_grandpa::{FinalityProofProvider as GrandpaFinalityProofProvider, SharedVoterState};
+use sc_finality_grandpa_rpc::GrandpaRpcHandler;
 use sc_service::{error::Error as ServiceError, Configuration, TaskManager};
 use sp_consensus_aura::sr25519::AuthorityPair as AuraPair;
 use sp_inherents::InherentDataProviders;
@@ -160,19 +161,33 @@ pub fn new_full(config: Configuration) -> Result<TaskManager, ServiceError> {
 	let telemetry_connection_sinks = sc_service::TelemetryConnectionSinks::default();
 
 	let rpc_extensions_builder = {
+		use sc_finality_grandpa_rpc::GrandpaApi;
 		use sc_rpc::DenyUnsafe;
 		use substrate_frame_rpc_system::{FullSystem, SystemApi};
 
 		let client = client.clone();
 		let pool = transaction_pool.clone();
 
-		Box::new(move |_, _| {
+		let justification_stream = grandpa_link.justification_stream();
+		let shared_authority_set = grandpa_link.shared_authority_set().clone();
+		let finality_proof_provider = GrandpaFinalityProofProvider::new_for_service(backend.clone(), client.clone());
+
+		Box::new(move |_, subscription_executor| {
+			let shared_voter_state = SharedVoterState::empty();
+
 			let mut io = jsonrpc_core::IoHandler::default();
 			io.extend_with(SystemApi::to_delegate(FullSystem::new(
 				client.clone(),
 				pool.clone(),
 				DenyUnsafe::No,
 			)));
+			io.extend_with(GrandpaApi::to_delegate(GrandpaRpcHandler::new(
+				shared_authority_set.clone(),
+				shared_voter_state,
+				justification_stream.clone(),
+				subscription_executor,
+				finality_proof_provider.clone(),
+			)));
 
 			io
 		})