Allow integrated relay chain light client (#2270)

* Add embedded light client to cli

* Prepare for light-client-worker

* First working version

* Clean up

* Remove unwanted logs

* Simplify subscription code

* Let jsonrpsee handle rpc management

* Simplify implementation

* Reorganize crate structure

* Use relay chain arg chainspec for light-client

* Clean up command line

* Add light client worker file

* Use smoldot master to avoid wasmtime conflict

* Remove sleep

* Improve naming of cli option

* Remove conflict with `validator`

* Improve docs

* Update smoldot, remove unwanted change

* Apply suggestions from code review

Co-authored-by: Dmitry Markin <dmitry@markin.tech>

* Disable collation

* Reviewer comments

* Update smoldot and tokio-platform

* Update smoldot

* Update smoldot

* Adjust to new version

* Patch substrate

* Use constants

* Add readme entry, improve zombienet tests

* Apply suggestions from code review

Co-authored-by: Michal Kucharczyk <1728078+michalkucharczyk@users.noreply.github.com>

* Make execution mode an enum

* Update smoldot, remove substrate patch

* Update client/relay-chain-rpc-interface/src/rpc_client.rs

Co-authored-by: Michal Kucharczyk <1728078+michalkucharczyk@users.noreply.github.com>

* Reduce duplicate code

* Update smoldot

* Update smoldot

* Fix build

* Update smoldot

* Make platform compile

* Clean up dependencies

* Use crates.io instead of github for smoldot

* Apply suggestions from code review

Co-authored-by: Davide Galassi <davxy@datawok.net>

* Docs

* Improve docs

* Remove `RpcFrontend`

---------

Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: Michal Kucharczyk <1728078+michalkucharczyk@users.noreply.github.com>
Co-authored-by: Davide Galassi <davxy@datawok.net>

cumulus/client/service/src/lib.rs

@@ -25,7 +25,9 @@ use cumulus_client_pov_recovery::{PoVRecovery, RecoveryDelayRange, RecoveryHandl
 use cumulus_primitives_core::{CollectCollationInfo, ParaId};
 use cumulus_relay_chain_inprocess_interface::build_inprocess_relay_chain;
 use cumulus_relay_chain_interface::{RelayChainInterface, RelayChainResult};
-use cumulus_relay_chain_minimal_node::build_minimal_relay_chain_node;
+use cumulus_relay_chain_minimal_node::{
+	build_minimal_relay_chain_node_light_client, build_minimal_relay_chain_node_with_rpc,
+};
 use futures::{
 	channel::{mpsc, oneshot},
 	FutureExt, StreamExt,
@@ -342,28 +344,30 @@ pub fn prepare_node_config(mut parachain_config: Configuration) -> Configuration
 /// Will return a minimal relay chain node with RPC
 /// client or an inprocess node, based on the [`CollatorOptions`] passed in.
 pub async fn build_relay_chain_interface(
-	polkadot_config: Configuration,
+	relay_chain_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>)> {
-	if !collator_options.relay_chain_rpc_urls.is_empty() {
-		build_minimal_relay_chain_node(
-			polkadot_config,
-			task_manager,
-			collator_options.relay_chain_rpc_urls,
-		)
-		.await
-	} else {
-		build_inprocess_relay_chain(
-			polkadot_config,
+	match collator_options.relay_chain_mode {
+		cumulus_client_cli::RelayChainMode::Embedded => build_inprocess_relay_chain(
+			relay_chain_config,
 			parachain_config,
 			telemetry_worker_handle,
 			task_manager,
 			hwbench,
-		)
+		),
+		cumulus_client_cli::RelayChainMode::ExternalRpc(rpc_target_urls) =>
+			build_minimal_relay_chain_node_with_rpc(
+				relay_chain_config,
+				task_manager,
+				rpc_target_urls,
+			)
+			.await,
+		cumulus_client_cli::RelayChainMode::LightClient =>
+			build_minimal_relay_chain_node_light_client(relay_chain_config, task_manager).await,
 	}
 }