allow config NextFreeParaId in genesis (#3781)

* allow config NextFreeParaId in genesis

* update westend chain spec

node/service/src/chain_spec.rs

@@ -534,6 +534,9 @@ fn westend_staging_testnet_config_genesis(wasm_binary: &[u8]) -> westend::Genesi
 			config: default_parachains_host_configuration(),
 		},
 		paras: Default::default(),
+		registrar: westend_runtime::RegistrarConfig {
+			next_free_para_id: polkadot_primitives::v1::LOWEST_PUBLIC_ID,
+		},
 	}
 }
 
@@ -1027,6 +1030,9 @@ fn rococo_staging_testnet_config_genesis(wasm_binary: &[u8]) -> rococo_runtime::
 		configuration: rococo_runtime::ConfigurationConfig {
 			config: default_parachains_host_configuration(),
 		},
+		registrar: rococo_runtime::RegistrarConfig {
+			next_free_para_id: polkadot_primitives::v1::LOWEST_PUBLIC_ID,
+		},
 		// bridge_rococo_grandpa: rococo_runtime::BridgeRococoGrandpaConfig {
 		// 	owner: Some(endowed_accounts[0].clone()),
 		// 	..Default::default()
@@ -1456,6 +1462,9 @@ pub fn westend_testnet_genesis(
 			config: default_parachains_host_configuration(),
 		},
 		paras: Default::default(),
+		registrar: westend_runtime::RegistrarConfig {
+			next_free_para_id: polkadot_primitives::v1::LOWEST_PUBLIC_ID,
+		},
 	}
 }
 
@@ -1526,6 +1535,9 @@ pub fn rococo_testnet_genesis(
 		},
 		hrmp: Default::default(),
 		paras: rococo_runtime::ParasConfig { paras: vec![] },
+		registrar: rococo_runtime::RegistrarConfig {
+			next_free_para_id: polkadot_primitives::v1::LOWEST_PUBLIC_ID,
+		},
 		// bridge_rococo_grandpa: rococo_runtime::BridgeRococoGrandpaConfig {
 		// 	owner: Some(root_key.clone()),
 		// 	..Default::default()

runtime/common/src/paras_registrar.rs

@@ -175,6 +175,25 @@ pub mod pallet {
 	#[pallet::storage]
 	pub type NextFreeParaId<T> = StorageValue<_, ParaId, ValueQuery>;
 
+	#[pallet::genesis_config]
+	pub struct GenesisConfig {
+		pub next_free_para_id: ParaId,
+	}
+
+	#[cfg(feature = "std")]
+	impl Default for GenesisConfig {
+		fn default() -> Self {
+			GenesisConfig { next_free_para_id: LOWEST_PUBLIC_ID }
+		}
+	}
+
+	#[pallet::genesis_build]
+	impl<T: Config> GenesisBuild<T> for GenesisConfig {
+		fn build(&self) {
+			NextFreeParaId::<T>::put(self.next_free_para_id);
+		}
+	}
+
 	#[pallet::hooks]
 	impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {}
 

runtime/rococo/src/lib.rs

@@ -226,7 +226,7 @@ construct_runtime! {
 		ParasDisputes: parachains_disputes::{Pallet, Storage, Event<T>},
 
 		// Parachain Onboarding Pallets
-		Registrar: paras_registrar::{Pallet, Call, Storage, Event<T>},
+		Registrar: paras_registrar::{Pallet, Call, Storage, Event<T>, Config},
 		Auctions: auctions::{Pallet, Call, Storage, Event<T>},
 		Crowdloan: crowdloan::{Pallet, Call, Storage, Event<T>},
 		Slots: slots::{Pallet, Call, Storage, Event<T>},

runtime/westend/src/lib.rs

@@ -1047,7 +1047,7 @@ construct_runtime! {
 		ParaSessionInfo: parachains_session_info::{Pallet, Storage} = 52,
 
 		// Parachain Onboarding Pallets. Start indices at 60 to leave room.
-		Registrar: paras_registrar::{Pallet, Call, Storage, Event<T>} = 60,
+		Registrar: paras_registrar::{Pallet, Call, Storage, Event<T>, Config} = 60,
 		Slots: slots::{Pallet, Call, Storage, Event<T>} = 61,
 		ParasSudoWrapper: paras_sudo_wrapper::{Pallet, Call} = 62,
 		Auctions: auctions::{Pallet, Call, Storage, Event<T>} = 63,