improve(relayer): Permit per-chain external listener customisation (#…

…1843)

This can be used to test a viem-based or non-evm-based external
listener.

src/relayer/RelayerClientHelper.ts

@@ -96,6 +96,7 @@ export async function constructRelayerClients(
         const opts = {
           lookback: config.maxRelayerLookBack,
           blockRange: config.maxBlockLookBack[chainId],
+          path: config.listenerPath[chainId],
         };
         return [chainId, await indexedSpokePoolClient(baseSigner, hubPoolClient, chainId, opts)];
       })

src/relayer/RelayerConfig.ts

@@ -28,7 +28,7 @@ type DepositConfirmationConfig = {
 
 export class RelayerConfig extends CommonConfig {
   readonly externalIndexer: boolean;
-  readonly indexerPath: string;
+  readonly listenerPath: { [chainId: number]: string } = {};
   readonly inventoryConfig: InventoryConfig;
   readonly debugProfitability: boolean;
   readonly sendingRelaysEnabled: boolean;
@@ -88,7 +88,6 @@ export class RelayerConfig extends CommonConfig {
       MIN_DEPOSIT_CONFIRMATIONS,
       RELAYER_IGNORE_LIMITS,
       RELAYER_EXTERNAL_INDEXER,
-      RELAYER_SPOKEPOOL_INDEXER_PATH,
       RELAYER_TRY_MULTICALL_CHAINS,
       RELAYER_USE_GENERIC_ADAPTER,
       RELAYER_LOGGING_INTERVAL = "30",
@@ -100,7 +99,6 @@ export class RelayerConfig extends CommonConfig {
 
     // External indexing is dependent on looping mode being configured.
     this.externalIndexer = this.pollingDelay > 0 && RELAYER_EXTERNAL_INDEXER === "true";
-    this.indexerPath = RELAYER_SPOKEPOOL_INDEXER_PATH ?? Constants.RELAYER_DEFAULT_SPOKEPOOL_INDEXER;
 
     // Empty means all chains.
     this.relayerOriginChains = JSON.parse(RELAYER_ORIGIN_CHAINS ?? "[]");
@@ -326,7 +324,7 @@ export class RelayerConfig extends CommonConfig {
    * @param logger Optional logger object.
    */
   override validate(chainIds: number[], logger: winston.Logger): void {
-    const { relayerOriginChains, relayerDestinationChains } = this;
+    const { listenerPath, minFillTime, relayerOriginChains, relayerDestinationChains } = this;
     const relayerChainIds =
       relayerOriginChains.length > 0 && relayerDestinationChains.length > 0
         ? dedupArray([...relayerOriginChains, ...relayerDestinationChains])
@@ -343,9 +341,13 @@ export class RelayerConfig extends CommonConfig {
       });
     }
 
-    chainIds.forEach(
-      (chainId) => (this.minFillTime[chainId] = Number(process.env[`RELAYER_MIN_FILL_TIME_${chainId}`] ?? 0))
-    );
+    const { RELAYER_SPOKEPOOL_INDEXER_PATH = Constants.RELAYER_DEFAULT_SPOKEPOOL_INDEXER } = process.env;
+
+    chainIds.forEach((chainId) => {
+      minFillTime[chainId] = Number(process.env[`RELAYER_MIN_FILL_TIME_${chainId}`] ?? 0);
+      listenerPath[chainId] =
+        process.env[`RELAYER_SPOKEPOOL_INDEXER_PATH_${chainId}`] ?? RELAYER_SPOKEPOOL_INDEXER_PATH;
+    });
 
     // Only validate config for chains that the relayer cares about.
     super.validate(relayerChainIds, logger);