chore: Log when validator enters commitee (#10615)

Entering the committee on a new epoch is logged as INFO, new epoch where
validator is not selected is VERBOSE.

```
[10:46:11.603] DEBUG: epoch-cache Initialized EpochCache with constants and validators {"l1constants":{"epochDuration":4,"ethereumSlotDuration":4,"l1GenesisTime":1733923582,"l1StartBlock":33,"slotDuration":8},"initialValidators":["0x3c44cdddb6a900fa2b585dd299e03d12fa4293bc","0x976ea74026e726554db657fa54763abd0c3a0aa9","0x70997970c51812dc3a010c7d01b50e0d17dc79c8"]}
[10:46:11.627] VERBOSE: validator Initialized validator with address 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266
[10:46:11.634] INFO: validator Started validator with address 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266
[10:46:38.639] DEBUG: epoch-cache Updating validator set for new epoch 38 {"epoch":38,"previousEpoch":37}
[10:46:38.646] DEBUG: epoch-cache Updated validator set for epoch 38 {"commitee":["0x3c44cdddb6a900fa2b585dd299e03d12fa4293bc","0x90f79bf6eb2c4f870365e785982e1f101e93b906","0x9965507d1a55bcc2695c58ba16fb37d819b0a4dc"]}
[10:46:38.646] VERBOSE: validator Validator 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266 not on the validator committee for epoch 38
[10:47:10.653] DEBUG: epoch-cache Updating validator set for new epoch 39 {"epoch":39,"previousEpoch":38}
[10:47:10.656] DEBUG: epoch-cache Updated validator set for epoch 39 {"commitee":["0x15d34aaf54267db7d7c367839aaf71a00a2c6a65","0x90f79bf6eb2c4f870365e785982e1f101e93b906","0x9965507d1a55bcc2695c58ba16fb37d819b0a4dc"]}
[10:47:10.656] VERBOSE: validator Validator 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266 not on the validator committee for epoch 39
[10:47:42.659] DEBUG: epoch-cache Updating validator set for new epoch 40 {"epoch":40,"previousEpoch":39}
[10:47:42.661] DEBUG: epoch-cache Updated validator set for epoch 40 {"commitee":["0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266","0x976ea74026e726554db657fa54763abd0c3a0aa9","0x15d34aaf54267db7d7c367839aaf71a00a2c6a65"]}
[10:47:42.661] INFO: validator Validator 0xf39fd6e51aad88f6f4ce6ab8827279cfffb92266 is on the validator committee for epoch 40
```

Fixes #10337

yarn-project/epoch-cache/src/epoch_cache.test.ts

@@ -102,7 +102,7 @@ describe('EpochCache', () => {
     expect(nextNextProposer).toEqual(testCommittee[0]);
   });
 
-  it('Should request to update the validator set when on the epoch boundary', async () => {
+  it('should request to update the validator set when on the epoch boundary', async () => {
     // Set initial time to a known slot
     const initialTime = Number(l1GenesisTime) * 1000; // Convert to milliseconds
     jest.setSystemTime(initialTime);

yarn-project/epoch-cache/src/epoch_cache.ts

@@ -8,6 +8,7 @@ import { RollupContract, createEthereumChain } from '@aztec/ethereum';
 import { EthAddress } from '@aztec/foundation/eth-address';
 import { type Logger, createLogger } from '@aztec/foundation/log';
 
+import { EventEmitter } from 'node:events';
 import { createPublicClient, encodeAbiParameters, http, keccak256 } from 'viem';
 
 import { type EpochCacheConfig, getEpochCacheConfigEnvVars } from './config.js';
@@ -28,7 +29,7 @@ type EpochAndSlot = {
  *
  * Note: This class is very dependent on the system clock being in sync.
  */
-export class EpochCache {
+export class EpochCache extends EventEmitter<{ committeeChanged: [EthAddress[], bigint] }> {
   private committee: EthAddress[];
   private cachedEpoch: bigint;
   private cachedSampleSeed: bigint;
@@ -40,6 +41,7 @@ export class EpochCache {
     initialSampleSeed: bigint = 0n,
     private readonly l1constants: L1RollupConstants = EmptyL1RollupConstants,
   ) {
+    super();
     this.committee = initialValidators;
     this.cachedSampleSeed = initialSampleSeed;
 
@@ -111,14 +113,19 @@ export class EpochCache {
     const { epoch: calculatedEpoch, ts } = nextSlot ? this.getEpochAndSlotInNextSlot() : this.getEpochAndSlotNow();
 
     if (calculatedEpoch !== this.cachedEpoch) {
-      this.log.debug(`Epoch changed, updating validator set`, { calculatedEpoch, cachedEpoch: this.cachedEpoch });
-      this.cachedEpoch = calculatedEpoch;
+      this.log.debug(`Updating validator set for new epoch ${calculatedEpoch}`, {
+        epoch: calculatedEpoch,
+        previousEpoch: this.cachedEpoch,
+      });
       const [committeeAtTs, sampleSeedAtTs] = await Promise.all([
         this.rollup.getCommitteeAt(ts),
         this.rollup.getSampleSeedAt(ts),
       ]);
       this.committee = committeeAtTs.map((v: `0x${string}`) => EthAddress.fromString(v));
+      this.cachedEpoch = calculatedEpoch;
       this.cachedSampleSeed = sampleSeedAtTs;
+      this.log.debug(`Updated validator set for epoch ${calculatedEpoch}`, { commitee: this.committee });
+      this.emit('committeeChanged', this.committee, calculatedEpoch);
     }
 
     return this.committee;

yarn-project/sequencer-client/src/client/sequencer-client.ts

@@ -81,7 +81,7 @@ export class SequencerClient {
       telemetryClient,
       config,
     );
-
+    await validatorClient?.start();
     await sequencer.start();
     return new SequencerClient(sequencer);
   }

yarn-project/sequencer-client/src/sequencer/sequencer.ts

@@ -204,6 +204,7 @@ export class Sequencer {
    */
   public async stop(): Promise<void> {
     this.log.debug(`Stopping sequencer`);
+    await this.validatorClient?.stop();
     await this.runningPromise?.stop();
     this.publisher.interrupt();
     this.setState(SequencerState.STOPPED, 0n, true /** force */);

yarn-project/validator-client/src/validator.ts

@@ -11,6 +11,7 @@ import { type EpochCache } from '@aztec/epoch-cache';
 import { Buffer32 } from '@aztec/foundation/buffer';
 import { type Fr } from '@aztec/foundation/fields';
 import { createLogger } from '@aztec/foundation/log';
+import { RunningPromise } from '@aztec/foundation/running-promise';
 import { sleep } from '@aztec/foundation/sleep';
 import { type Timer } from '@aztec/foundation/timer';
 import { type P2P } from '@aztec/p2p';
@@ -68,6 +69,8 @@ export class ValidatorClient extends WithTracer implements Validator {
   // Callback registered to: sequencer.buildBlock
   private blockBuilder?: BlockBuilderCallback = undefined;
 
+  private epochCacheUpdateLoop: RunningPromise;
+
   constructor(
     private keyStore: ValidatorKeyStore,
     private epochCache: EpochCache,
@@ -81,7 +84,23 @@ export class ValidatorClient extends WithTracer implements Validator {
     this.metrics = new ValidatorMetrics(telemetry);
 
     this.validationService = new ValidationService(keyStore);
-    this.log.verbose('Initialized validator');
+
+    // Refresh epoch cache every second to trigger commiteeChanged event
+    this.epochCacheUpdateLoop = new RunningPromise(async () => {
+      await this.epochCache.getCommittee().catch(err => log.error('Error updating validator committee', err));
+    }, 1000);
+
+    // Listen to commiteeChanged event to alert operator when their validator has entered the committee
+    this.epochCache.on('committeeChanged', (newCommittee, epochNumber) => {
+      const me = this.keyStore.getAddress();
+      if (newCommittee.some(addr => addr.equals(me))) {
+        this.log.info(`Validator ${me.toString()} is on the validator committee for epoch ${epochNumber}`);
+      } else {
+        this.log.verbose(`Validator ${me.toString()} not on the validator committee for epoch ${epochNumber}`);
+      }
+    });
+
+    this.log.verbose(`Initialized validator with address ${this.keyStore.getAddress().toString()}`);
   }
 
   static new(
@@ -102,14 +121,25 @@ export class ValidatorClient extends WithTracer implements Validator {
     return validator;
   }
 
-  public start() {
+  public async start() {
     // Sync the committee from the smart contract
     // https://github.com/AztecProtocol/aztec-packages/issues/7962
 
-    this.log.info('Validator started');
+    const me = this.keyStore.getAddress();
+    const inCommittee = await this.epochCache.isInCommittee(me);
+    if (inCommittee) {
+      this.log.info(`Started validator with address ${me.toString()} in current validator committee`);
+    } else {
+      this.log.info(`Started validator with address ${me.toString()}`);
+    }
+    this.epochCacheUpdateLoop.start();
     return Promise.resolve();
   }
 
+  public async stop() {
+    await this.epochCacheUpdateLoop.stop();
+  }
+
   public registerBlockProposalHandler() {
     const handler = (block: BlockProposal): Promise<BlockAttestation | undefined> => {
       return this.attestToProposal(block);