feat(ccip-gateway): Improve Reliability of the CCIP Gateway

packages/linea-ccip-gateway/.env.example

@@ -1,6 +1,8 @@
 PORT=8081
 
-L1_PROVIDER_URL=http://127.0.0.1:8545
+L1_PROVIDER_URL=https://ethereum-sepolia-rpc.publicnode.com
+L1_PROVIDER_URL_FALLBACK=https://sepolia.gateway.tenderly.co
 L2_PROVIDER_URL=https://rpc.sepolia.linea.build/
+L2_PROVIDER_URL_FALLBACK=https://linea-sepolia-rpc.publicnode.com
 L1_ROLLUP_ADDRESS=0xB218f8A4Bc926cF1cA7b3423c154a0D627Bdb7E5
 L2_CHAIN_ID=59141

packages/linea-ccip-gateway/src/L2ProofService.ts

@@ -3,7 +3,7 @@ import {
   AddressLike,
   Contract,
   ethers,
-  JsonRpcProvider,
+  FallbackProvider,
 } from 'ethers';
 import { EVMProofHelper, IProofService, StateProof } from './evm-gateway';
 import { logDebug, logError } from './utils';
@@ -23,12 +23,11 @@ export class L2ProofService implements IProofService<L2ProvableBlock> {
   private readonly helper: EVMProofHelper;
 
   constructor(
-    providerL1: JsonRpcProvider,
-    providerL2: JsonRpcProvider,
+    providerL1: FallbackProvider,
+    providerL2: FallbackProvider,
     rollupAddress: string,
-    shomeiNode?: JsonRpcProvider,
   ) {
-    this.helper = new EVMProofHelper(providerL2, shomeiNode);
+    this.helper = new EVMProofHelper(providerL2);
     const currentL2BlockNumberIface = new ethers.Interface([
       currentL2BlockNumberSig,
     ]);

packages/linea-ccip-gateway/src/evm-gateway/EVMProofHelper.ts

@@ -1,4 +1,9 @@
-import { AddressLike, ethers, JsonRpcProvider, toBeHex } from 'ethers';
+import {
+  AddressLike,
+  FallbackProvider,
+  JsonRpcProvider,
+  toBeHex,
+} from 'ethers';
 import { logDebug, logInfo } from '../utils';
 
 interface ProofStruct {
@@ -26,13 +31,10 @@ export interface StateProof {
  *
  */
 export class EVMProofHelper {
-  private readonly providerL2: JsonRpcProvider;
-  private readonly shomeiNode: JsonRpcProvider;
+  private readonly providerL2: FallbackProvider;
 
-  constructor(providerL2: JsonRpcProvider, shomeiNode?: JsonRpcProvider) {
+  constructor(providerL2: FallbackProvider) {
     this.providerL2 = providerL2;
-    // shomeiNode optional since an rpc infura nodes can support both eth_getStorageAt and linea_getProof
-    this.shomeiNode = shomeiNode ? shomeiNode : providerL2;
   }
 
   /**
@@ -63,29 +65,43 @@ export class EVMProofHelper {
     address: AddressLike,
     slots: bigint[],
   ): Promise<StateProof> {
-    const args = [
+    const args: (AddressLike | string[])[] = [
       address,
       slots.map(slot => toBeHex(slot, 32)),
       '0x' + blockNo.toString(16),
     ];
 
     logInfo('Calling linea_getProof with args', args);
 
-    // We have to reinitilize the provider L2 because of an issue when multiple
+    // We have to reinitialize the provider L2 because of an issue when multiple
     // requests are sent at the same time, the provider becomes not aware of
     // the linea_getProof method
-    const providerUrl = this.shomeiNode._getConnection().url;
-    const providerChainId = this.shomeiNode._network.chainId;
-    const providerL2 = new ethers.JsonRpcProvider(
-      providerUrl,
-      providerChainId,
-      {
-        staticNetwork: true,
-      },
-    );
-    logDebug('Calling linea_getProof with L2 provider', providerUrl);
-    const proofs: StateProof = await providerL2.send('linea_getProof', args);
-    logDebug('Proof result', proofs);
-    return proofs;
+
+    const providerConfigs = this.providerL2.providerConfigs;
+
+    for (const config of providerConfigs) {
+      const provider = config.provider;
+
+      if (provider instanceof JsonRpcProvider) {
+        try {
+          logDebug(
+            `Trying provider with URL: ${provider._getConnection().url}`,
+          );
+          const proofs: StateProof = await provider.send(
+            'linea_getProof',
+            args,
+          );
+
+          logDebug('Proof result from provider:', proofs);
+          return proofs;
+        } catch (error) {
+          logInfo(`Provider failed: ${provider._getConnection().url}`, error);
+        }
+      } else {
+        logInfo('Skipped non-JsonRpcProvider provider in fallback');
+      }
+    }
+
+    throw new Error('All providers failed to fetch linea_getProof');
   }
 }

packages/linea-ccip-gateway/src/index.ts

@@ -1,17 +1,16 @@
 import { EVMGateway } from './evm-gateway';
-import { JsonRpcProvider } from 'ethers';
+import { FallbackProvider } from 'ethers';
 import { L2ProofService, L2ProvableBlock } from './L2ProofService';
 
 export type L1Gateway = EVMGateway<L2ProvableBlock>;
 
 export function makeL2Gateway(
-  providerL1: JsonRpcProvider,
-  providerL2: JsonRpcProvider,
+  providerL1: FallbackProvider,
+  providerL2: FallbackProvider,
   rollupAddress: string,
-  shomeiNode?: JsonRpcProvider,
 ): L1Gateway {
   return new EVMGateway(
-    new L2ProofService(providerL1, providerL2, rollupAddress, shomeiNode),
+    new L2ProofService(providerL1, providerL2, rollupAddress),
   );
 }
 

packages/linea-ccip-gateway/src/server.ts

@@ -1,24 +1,33 @@
 import { Request, Response } from 'express';
 import { EVMGateway } from './evm-gateway';
-import { ethers } from 'ethers';
+import { FallbackProvider, JsonRpcProvider } from 'ethers';
 import { L2ProofService } from './L2ProofService';
 import 'dotenv/config';
 import { Server } from '@chainlink/ccip-read-server';
 import { logError } from './utils';
 
 const l1ProviderUrl = process.env.L1_PROVIDER_URL;
+const l1ProviderUrlFallback = process.env.L1_PROVIDER_URL_FALLBACK;
 const l2ProviderUrl = process.env.L2_PROVIDER_URL;
+const l2ProviderUrlFallback = process.env.L2_PROVIDER_URL_FALLBACK;
 const l2ChainId = parseInt(process.env.L2_CHAIN_ID ?? '59141');
 const rollupAddress =
   process.env.L1_ROLLUP_ADDRESS ?? '0xB218f8A4Bc926cF1cA7b3423c154a0D627Bdb7E5';
 const port = process.env.PORT || 3000;
 const nodeEnv = process.env.NODE_ENV || 'test';
 
 try {
-  const providerL1 = new ethers.JsonRpcProvider(l1ProviderUrl);
-  const providerL2 = new ethers.JsonRpcProvider(l2ProviderUrl, l2ChainId, {
-    staticNetwork: true,
-  });
+  const providerL1 = new FallbackProvider([
+    new JsonRpcProvider(l1ProviderUrl),
+    new JsonRpcProvider(l1ProviderUrlFallback),
+  ]);
+  const providerL2 = new FallbackProvider(
+    [
+      new JsonRpcProvider(l2ProviderUrl),
+      new JsonRpcProvider(l2ProviderUrlFallback),
+    ],
+    l2ChainId,
+  );
 
   const gateway = new EVMGateway(
     new L2ProofService(providerL1, providerL2, rollupAddress),

packages/linea-ccip-gateway/test/constants.ts

@@ -1,5 +1,5 @@
-export const L1_RPC_URL = 'https://gateway.tenderly.co/public/sepolia';
-export const L2_RPC_URL = 'https://rpc.sepolia.linea.build/';
+export const L1_RPC_URL = 'https://ethereum-sepolia-rpc.publicnode.com';
+export const L2_RPC_URL = 'https://rpc.sepolia.linea.build';
 export const L2_TEST_CONTRACT_ADDRESS =
   '0x09a434561f4b40067F71444d7042fd110013F879';
 export const ROLLUP_SEPOLIA_ADDRESS =

packages/linea-ccip-gateway/test/testVerifier.spec.ts

@@ -7,6 +7,7 @@ import {
   BrowserProvider,
   Contract,
   ethers,
+  FallbackProvider,
   FetchRequest,
   JsonRpcProvider,
   Signer,
@@ -75,8 +76,8 @@ describe('L1Verifier', () => {
     const rollup = await Rollup.deploy(currentL2BlockNumber, stateRootHash);
 
     const gateway = makeL2Gateway(
-      (l1Provider as unknown) as JsonRpcProvider,
-      l2Provider,
+      new FallbackProvider([(l1Provider as unknown) as JsonRpcProvider]),
+      new FallbackProvider([l2Provider]),
       await rollup.getAddress(),
     );
     const server = new Server();