feat(relay): Add fallback node structure

beacon-light-client/solidity/tasks/deploy.ts

@@ -22,7 +22,7 @@ task('deploy', 'Deploy the beacon light client contract')
     console.log('Deploying contracts with the account:', deployer.address);
     console.log('Account balance:', (await deployer.getBalance()).toString());
 
-    const beaconApi = new BeaconApi(currentConfig.BEACON_REST_API);
+    const beaconApi = new BeaconApi([currentConfig.BEACON_REST_API]);
 
     const beaconLightClient = await (
       await ethers.getContractFactory('BeaconLightClient')

beacon-light-client/solidity/tasks/start-publishing.ts

@@ -81,7 +81,7 @@ task('start-publishing', 'Run relayer')
     }
 
     const redis = new Redis(config.REDIS_HOST!, config.REDIS_PORT);
-    const beaconApi = new BeaconApi(currentConfig.BEACON_REST_API);
+    const beaconApi = new BeaconApi([currentConfig.BEACON_REST_API]);
     const contract = new SolidityContract(
       lightClientContract,
       (network.config as any).url,

beacon-light-client/solidity/tasks/verify-contracts.ts

@@ -17,7 +17,7 @@ task('verify-contracts', 'Verify')
 
     const currentConfig = networkConfig[args.follownetwork] as Config;
 
-    const beaconApi = new BeaconApi(currentConfig.BEACON_REST_API!);
+    const beaconApi = new BeaconApi([currentConfig.BEACON_REST_API!]);
 
     await run('verify:verify', {
       address: args.lightclient,

relay/implementations/beacon-api.ts

@@ -13,10 +13,12 @@ import { computeSyncCommitteePeriodAt } from '../../libs/typescript/ts-utils/ssz
 import path from 'path';
 
 export class BeaconApi implements IBeaconApi {
-  private beaconRestApi: string;
+  private beaconRestApis: string[];
+  private currentApiIndex: number;
 
-  constructor(beaconRestApi: string) {
-    this.beaconRestApi = beaconRestApi;
+  constructor(beaconRestApis: string[]) {
+    this.beaconRestApis = beaconRestApis;
+    this.currentApiIndex = 0;
   }
 
   async getHashiAdapterInfo(slot: number): Promise<{
@@ -26,7 +28,9 @@ export class BeaconApi implements IBeaconApi {
     blockHashProof: string[];
   }> {
     const currentBlock = await (
-      await fetch(this.concatUrl(`/eth/v2/beacon/blocks/${slot}`))
+      await this.fetchWithFallback(
+        this.concatUrl(`/eth/v2/beacon/blocks/${slot}`),
+      )
     ).json();
 
     const { ssz } = await import('@lodestar/types');
@@ -78,15 +82,19 @@ export class BeaconApi implements IBeaconApi {
 
   async getCurrentHeadSlot(): Promise<number> {
     const currentHead = await (
-      await fetch(this.concatUrl('/eth/v1/beacon/headers/head'))
+      await this.fetchWithFallback(
+        this.concatUrl('/eth/v1/beacon/headers/head'),
+      )
     ).json();
 
     return Number(currentHead.data.header.message.slot);
   }
 
   async getBlockSlot(blockHash: string): Promise<number> {
     const headResult = await (
-      await fetch(this.concatUrl(`/eth/v1/beacon/headers/${blockHash}`))
+      await this.fetchWithFallback(
+        this.concatUrl(`/eth/v1/beacon/headers/${blockHash}`),
+      )
     ).json();
 
     return Number(headResult.data.header.message.slot);
@@ -104,7 +112,9 @@ export class BeaconApi implements IBeaconApi {
     const { ssz } = await import('@lodestar/types');
 
     const headResult = await (
-      await fetch(this.concatUrl(`/eth/v1/beacon/headers/${slot}`))
+      await this.fetchWithFallback(
+        this.concatUrl(`/eth/v1/beacon/headers/${slot}`),
+      )
     ).json();
 
     return ssz.phase0.BeaconBlockHeader.fromJson(
@@ -130,7 +140,9 @@ export class BeaconApi implements IBeaconApi {
 
     while (slot <= limitSlot) {
       blockHeaderResult = await (
-        await fetch(this.concatUrl(`/eth/v1/beacon/headers/${slot}`))
+        await this.fetchWithFallback(
+          this.concatUrl(`/eth/v1/beacon/headers/${slot}`),
+        )
       ).json();
 
       if (blockHeaderResult.code !== 404) {
@@ -155,7 +167,9 @@ export class BeaconApi implements IBeaconApi {
 
     while (slot <= limitSlot) {
       blockHeaderBodyResult = await (
-        await fetch(this.concatUrl(`/eth/v2/beacon/blocks/${slot}`))
+        await this.fetchWithFallback(
+          this.concatUrl(`/eth/v2/beacon/blocks/${slot}`),
+        )
       ).json();
 
       if (blockHeaderBodyResult.code !== 404) {
@@ -195,7 +209,7 @@ export class BeaconApi implements IBeaconApi {
       await this.getBeaconState(prevSlot);
 
     const prevFinalizedHeaderResult = await (
-      await fetch(
+      await this.fetchWithFallback(
         this.concatUrl(
           `/eth/v1/beacon/headers/${
             '0x' + bytesToHex(prevBeaconSate.finalizedCheckpoint.root)
@@ -275,7 +289,7 @@ export class BeaconApi implements IBeaconApi {
     const { beaconState, stateTree } = await this.getBeaconState(slot);
 
     const finalizedHeaderResult = await (
-      await fetch(
+      await this.fetchWithFallback(
         this.concatUrl(
           `/eth/v1/beacon/headers/${
             '0x' + bytesToHex(beaconState.finalizedCheckpoint.root)
@@ -305,7 +319,9 @@ export class BeaconApi implements IBeaconApi {
     const { ssz } = await import('@lodestar/types');
 
     const finalizedBlockBodyResult = await (
-      await fetch(this.concatUrl(`/eth/v2/beacon/blocks/${slot}`))
+      await this.fetchWithFallback(
+        this.concatUrl(`/eth/v2/beacon/blocks/${slot}`),
+      )
     ).json();
 
     const finalizedBlockBody = ssz.capella.BeaconBlockBody.fromJson(
@@ -345,13 +361,13 @@ export class BeaconApi implements IBeaconApi {
     const { ssz } = await import('@lodestar/types');
 
     const finality_checkpoints = await (
-      await fetch(
+      await this.fetchWithFallback(
         this.concatUrl(`/eth/v1/beacon/states/${slot}/finality_checkpoints`),
       )
     ).json();
 
     const finalizedHeadResult = await (
-      await fetch(
+      await this.fetchWithFallback(
         this.concatUrl(
           `/eth/v1/beacon/headers/${finality_checkpoints.data.finalized.root}`,
         ),
@@ -365,7 +381,9 @@ export class BeaconApi implements IBeaconApi {
 
   async getExecutionStateRoot(slot: number): Promise<string> {
     const block = await (
-      await fetch(this.concatUrl(`/eth/v2/beacon/blocks/${slot}`))
+      await this.fetchWithFallback(
+        this.concatUrl(`/eth/v2/beacon/blocks/${slot}`),
+      )
     ).json();
 
     return block.data.message.body.execution_payload.state_root;
@@ -374,7 +392,7 @@ export class BeaconApi implements IBeaconApi {
   private async getBeaconState(slot: number) {
     const { ssz } = await import('@lodestar/types');
 
-    const beaconStateSZZ = await fetch(
+    const beaconStateSZZ = await this.fetchWithFallback(
       this.concatUrl(`/eth/v2/debug/beacon/states/${slot}`),
       {
         headers: {
@@ -392,8 +410,37 @@ export class BeaconApi implements IBeaconApi {
     return { beaconState, stateTree };
   }
 
+  private nextApi(): void {
+    this.currentApiIndex =
+      (this.currentApiIndex + 1) % this.beaconRestApis.length;
+  }
+
+  private getCurrentApi(): string {
+    return this.beaconRestApis[this.currentApiIndex];
+  }
+
+  private async fetchWithFallback(
+    input: RequestInfo | URL,
+    init?: RequestInit,
+  ): Promise<Response> {
+    let retries = 0;
+    while (true) {
+      try {
+        return await fetch(input, init);
+      } catch (error) {
+        if (retries >= this.beaconRestApis.length) {
+          throw error;
+        }
+
+        retries++;
+
+        this.nextApi();
+      }
+    }
+  }
+
   private concatUrl(urlPath: string): string {
-    const url = new URL(this.beaconRestApi);
+    const url = new URL(this.getCurrentApi());
     url.pathname = path.join(url.pathname, urlPath);
 
     return url.href;

relay/workers/poll-updates/poll-updates-worker.ts

@@ -53,7 +53,7 @@ import { checkConfig } from '../../../libs/typescript/ts-utils/common-utils';
 
       doUpdate(
         redis,
-        new BeaconApi(job.data.beaconRestApi),
+        new BeaconApi([job.data.beaconRestApi]),
         proofGenertorQueue,
         job.data.lastDownloadedUpdateKey,
         job.data.slotsJump,