fix: add data fetcher debug logs (#165)

# What ❔

Add more Data Fetcher debug logs.

## Why ❔

For easier troubleshooting.

## Checklist

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<!-- For draft PRs check the boxes as you complete them. -->

- [X] PR title corresponds to the body of PR (we generate changelog
entries from PRs).
- [X] Tests for the changes have been added / updated.

packages/data-fetcher/src/block/block.service.ts

@@ -46,7 +46,7 @@ export class BlockService {
   public async getData(blockNumber: number): Promise<BlockData | null> {
     const stopDurationMeasuring = this.processingDurationMetric.startTimer();
 
-    this.logger.debug({ message: "Getting block from the blockchain", blockNumber });
+    this.logger.debug({ message: "Getting block data from the blockchain", blockNumber });
     const stopGetBlockInfoDurationMetric = this.getBlockInfoDurationMetric.startTimer();
     const [block, blockDetails] = await Promise.all([
       this.blockchainService.getBlock(blockNumber),
@@ -90,6 +90,7 @@ export class BlockService {
       stopDurationMeasuring({ status: blockProcessingStatus, action: "get" });
     }
 
+    this.logger.debug({ message: "Successfully generated block data", blockNumber });
     return {
       block,
       blockDetails,

packages/data-fetcher/src/health/health.controller.spec.ts

@@ -81,4 +81,11 @@ describe("HealthController", () => {
       });
     });
   });
+
+  describe("onApplicationShutdown", () => {
+    it("defined and returns void", async () => {
+      const result = healthController.onApplicationShutdown();
+      expect(result).toBeUndefined();
+    });
+  });
 });

packages/data-fetcher/src/health/health.controller.ts

@@ -1,9 +1,9 @@
-import { Logger, Controller, Get } from "@nestjs/common";
+import { Logger, Controller, Get, OnApplicationShutdown } from "@nestjs/common";
 import { HealthCheckService, HealthCheck, HealthCheckResult } from "@nestjs/terminus";
 import { JsonRpcHealthIndicator } from "./jsonRpcProvider.health";
 
 @Controller(["health", "ready"])
-export class HealthController {
+export class HealthController implements OnApplicationShutdown {
   private readonly logger: Logger;
 
   constructor(
@@ -17,10 +17,18 @@ export class HealthController {
   @HealthCheck()
   public async check(): Promise<HealthCheckResult> {
     try {
-      return await this.healthCheckService.check([() => this.jsonRpcHealthIndicator.isHealthy("jsonRpcProvider")]);
+      const healthCheckResult = await this.healthCheckService.check([
+        () => this.jsonRpcHealthIndicator.isHealthy("jsonRpcProvider"),
+      ]);
+      this.logger.debug({ message: "Health check result", ...healthCheckResult });
+      return healthCheckResult;
     } catch (error) {
       this.logger.error({ message: error.message, response: error.getResponse() }, error.stack);
       throw error;
     }
   }
+
+  onApplicationShutdown(signal?: string): void {
+    this.logger.debug({ message: "Received a signal", signal });
+  }
 }