Allow to specify multiple relay chain RPC urls for collator node (#1880)

* Allow specification of multiple urls for relay chain rpc nodes

* Add pooled RPC client basics

* Add list of clients to pooled client

* Improve

* Forward requests to dispatcher

* Switch clients on error

* Implement rotation logic

* Improve subscription handling

* Error handling cleanup

* Remove retry from rpc-client

* Improve naming

* Improve documentation

* Improve `ClientManager` abstraction

* Adjust zombienet test

* Add more comments

* fmt

* Apply reviewers comments

* Extract reconnection to extra method

* Add comment to reconnection method

* Clean up some dependencies

* Fix build

* fmt

* Provide alias for cli argument

* Apply review comments

* Rename P* to Relay*

* Improve zombienet test

* fmt

* Fix zombienet sleep

* Simplify zombienet test

* Reduce log clutter and fix starting position

* Do not distribute duplicated imported and finalized blocks

* fmt

* Apply code review suggestions

* Move building of relay chain interface to `cumulus-client-service`

* Refactoring to not push back into channel

* FMT

parachain-template/node/src/command.rs

@@ -288,7 +288,7 @@ pub fn run() -> Result<()> {
 				info!("Parachain genesis state: {}", genesis_state);
 				info!("Is collating: {}", if config.role.is_authority() { "yes" } else { "no" });
 
-				if collator_options.relay_chain_rpc_url.is_some() && cli.relay_chain_args.len() > 0 {
+				if !collator_options.relay_chain_rpc_urls.is_empty() && cli.relay_chain_args.len() > 0 {
 					warn!("Detected relay chain node arguments together with --relay-chain-rpc-url. This command starts a minimal Polkadot node that only uses a network-related subset of all relay chain CLI options.");
 				}
 

parachain-template/node/src/service.rs

@@ -14,12 +14,11 @@ use cumulus_client_consensus_common::{
 };
 use cumulus_client_network::BlockAnnounceValidator;
 use cumulus_client_service::{
-	prepare_node_config, start_collator, start_full_node, StartCollatorParams, StartFullNodeParams,
+	build_relay_chain_interface, prepare_node_config, start_collator, start_full_node,
+	StartCollatorParams, StartFullNodeParams,
 };
 use cumulus_primitives_core::ParaId;
-use cumulus_relay_chain_inprocess_interface::build_inprocess_relay_chain;
-use cumulus_relay_chain_interface::{RelayChainError, RelayChainInterface, RelayChainResult};
-use cumulus_relay_chain_minimal_node::build_minimal_relay_chain_node;
+use cumulus_relay_chain_interface::{RelayChainError, RelayChainInterface};
 
 // Substrate Imports
 use sc_consensus::ImportQueue;
@@ -31,8 +30,6 @@ use sc_telemetry::{Telemetry, TelemetryHandle, TelemetryWorker, TelemetryWorkerH
 use sp_keystore::SyncCryptoStorePtr;
 use substrate_prometheus_endpoint::Registry;
 
-use polkadot_service::CollatorPair;
-
 /// Native executor type.
 pub struct ParachainNativeExecutor;
 
@@ -136,27 +133,6 @@ pub fn new_partial(
 	})
 }
 
-async fn build_relay_chain_interface(
-	polkadot_config: Configuration,
-	parachain_config: &Configuration,
-	telemetry_worker_handle: Option<TelemetryWorkerHandle>,
-	task_manager: &mut TaskManager,
-	collator_options: CollatorOptions,
-	hwbench: Option<sc_sysinfo::HwBench>,
-) -> RelayChainResult<(Arc<(dyn RelayChainInterface + 'static)>, Option<CollatorPair>)> {
-	match collator_options.relay_chain_rpc_url {
-		Some(relay_chain_url) =>
-			build_minimal_relay_chain_node(polkadot_config, task_manager, relay_chain_url).await,
-		None => build_inprocess_relay_chain(
-			polkadot_config,
-			parachain_config,
-			telemetry_worker_handle,
-			task_manager,
-			hwbench,
-		),
-	}
-}
-
 /// Start a node with the given parachain `Configuration` and relay chain `Configuration`.
 ///
 /// This is the actual implementation that is abstract over the executor and the runtime api.