omni-node: add metadata checks for runtime/parachain compatibility

cumulus/polkadot-omni-node/lib/Cargo.toml

@@ -13,6 +13,7 @@ workspace = true
 path = "src/lib.rs"
 
 [dependencies]
+anyhow = { workspace = true }
 async-trait = { workspace = true }
 clap = { features = ["derive"], workspace = true }
 codec = { workspace = true, default-features = true }
@@ -26,6 +27,9 @@ docify = { workspace = true }
 # Local
 jsonrpsee = { features = ["server"], workspace = true }
 parachains-common = { workspace = true, default-features = true }
+frame-metadata = { workspace = true, default-features = true, features = [
+	"decode",
+] }
 
 # Substrate
 frame-benchmarking = { optional = true, workspace = true, default-features = true }
@@ -94,12 +98,8 @@ wait-timeout = { workspace = true }
 
 [features]
 default = []
-rococo-native = [
-	"polkadot-cli/rococo-native",
-]
-westend-native = [
-	"polkadot-cli/westend-native",
-]
+rococo-native = ["polkadot-cli/rococo-native"]
+westend-native = ["polkadot-cli/westend-native"]
 runtime-benchmarks = [
 	"cumulus-primitives-core/runtime-benchmarks",
 	"frame-benchmarking-cli/runtime-benchmarks",

cumulus/polkadot-omni-node/lib/src/common/runtime.rs

@@ -66,3 +66,28 @@ impl RuntimeResolver for DefaultRuntimeResolver {
 		Ok(Runtime::Omni(BlockNumber::U32, Consensus::Aura(AuraConsensusId::Sr25519)))
 	}
 }
+
+/// Logic that inspects runtime's metadata for Omni Node compatibility.
+pub mod metadata {
+	use frame_metadata::{RuntimeMetadata, RuntimeMetadataPrefixed};
+	use sp_core::Decode;
+
+	/// Checks if pallet exists in runtime's metadata.
+	///
+	/// Metadata (as plain byte array) is decoded with `sp_core::Decode` and
+	/// pallets existance is checked by looking for pallets with certain names.
+	pub fn pallet_exists<'a>(
+		mut metadata: &'a [u8],
+		name: &str,
+	) -> Result<bool, sc_service::error::Error> {
+		let decoded_metadata = RuntimeMetadataPrefixed::decode(&mut metadata)
+			.map_err(|e| sc_service::error::Error::Application(Box::new(e) as Box<_>))?;
+		match decoded_metadata.1 {
+			RuntimeMetadata::V14(inner) => Ok(inner.pallets.iter().any(|p| p.name == name)),
+			RuntimeMetadata::V15(inner) => Ok(inner.pallets.iter().any(|p| p.name == name)),
+			_ => Err(sc_service::error::Error::Application(
+				anyhow::anyhow!("Metadata version lower than 14 not supported.").into(),
+			)),
+		}
+	}
+}

cumulus/polkadot-omni-node/lib/src/common/spec.rs

@@ -14,14 +14,17 @@
 // You should have received a copy of the GNU General Public License
 // along with Cumulus.  If not, see <http://www.gnu.org/licenses/>.
 
-use crate::common::{
-	command::NodeCommandRunner,
-	rpc::BuildRpcExtensions,
-	types::{
-		ParachainBackend, ParachainBlockImport, ParachainClient, ParachainHostFunctions,
-		ParachainService,
+use crate::{
+	common::{
+		command::NodeCommandRunner,
+		rpc::BuildRpcExtensions,
+		types::{
+			ParachainBackend, ParachainBlockImport, ParachainClient, ParachainHostFunctions,
+			ParachainService,
+		},
+		ConstructNodeRuntimeApi, NodeBlock, NodeExtraArgs,
 	},
-	ConstructNodeRuntimeApi, NodeBlock, NodeExtraArgs,
+	runtime::metadata::pallet_exists,
 };
 use cumulus_client_cli::CollatorOptions;
 use cumulus_client_service::{
@@ -41,9 +44,12 @@ use sc_sysinfo::HwBench;
 use sc_telemetry::{TelemetryHandle, TelemetryWorker};
 use sc_tracing::tracing::Instrument;
 use sc_transaction_pool::TransactionPoolHandle;
+use sp_api::{Metadata, ProvideRuntimeApi};
 use sp_keystore::KeystorePtr;
 use std::{future::Future, pin::Pin, sync::Arc, time::Duration};
 
+const DEFAULT_PARACHAIN_SYSTEM_PALLET_NAME: &str = "ParachainSystem";
+
 pub(crate) trait BuildImportQueue<Block: BlockT, RuntimeApi> {
 	fn build_import_queue(
 		client: Arc<ParachainClient<Block, RuntimeApi>>,
@@ -214,10 +220,33 @@ pub(crate) trait NodeSpec: BaseNodeSpec {
 
 				let params = Self::new_partial(&parachain_config)?;
 				let (block_import, mut telemetry, telemetry_worker_handle) = params.other;
-
 				let client = params.client.clone();
-				let backend = params.backend.clone();
 
+				// Best effort check of parachain-system pallet by pallet name.
+				let best_block = client.chain_info().finalized_hash;
+				// The `Metadata::metadata()` API returns only metadata according
+				// to V14 schema. It would be great to return the latest stable
+				// version in the future. There is an alternative to pick the latest
+				// by going through `metadata_versions` and then pick the maximum
+				// with `metadata_at_version`, but that's more code for no real benefit.
+				// The following code is fine with whichever metadata version
+				// contains pallet information, includding their names.
+				let metadata = client
+					.runtime_api()
+					.metadata(best_block)
+					.map_err(|e| sc_service::Error::Application(Box::new(e) as Box<_>))?;
+
+				if !pallet_exists(metadata.as_slice(), DEFAULT_PARACHAIN_SYSTEM_PALLET_NAME)? {
+					log::warn!(
+						r#"⚠️ The parachain system pallet (https://docs.rs/crate/cumulus-pallet-parachain-system/latest) is
+			missing from the runtime’s metadata. Omni Node requires this pallet to be defined as `ParachainSystem`
+			in your runtime. If your setup uses a different name for the `cumulus_parachain_system_pallet`, Omni Node
+			might still work, but it's recommended to name it `ParachainSystem`. Not following this naming convention
+			could cause issues, as future development expects the type to be named `ParachainSystem`."#,
+					);
+				}
+
+				let backend = params.backend.clone();
 				let mut task_manager = params.task_manager;
 				let (relay_chain_interface, collator_key) = build_relay_chain_interface(
 					polkadot_config,