add my first EMF metrics to upsert letter lambda

Author: Vlasis-Perdikidis

lambdas/upsert-letter/package.json

@@ -7,6 +7,7 @@
     "@nhsdigital/nhs-notify-event-schemas-letter-rendering-v1": "npm:@nhsdigital/nhs-notify-event-schemas-letter-rendering@^1.1.5",
     "@nhsdigital/nhs-notify-event-schemas-supplier-api": "^1.0.8",
     "@types/aws-lambda": "^8.10.148",
+    "aws-embedded-metrics": "^4.2.1",
     "aws-lambda": "^1.0.7",
     "esbuild": "^0.27.2",
     "pino": "^9.7.0",

lambdas/upsert-letter/src/handler/upsert-handler.ts

@@ -19,6 +19,7 @@ import {
   LetterRequestPreparedEventV2,
 } from "@nhsdigital/nhs-notify-event-schemas-letter-rendering";
 import z from "zod";
+import { metricScope, Unit } from "aws-embedded-metrics";
 import { Deps } from "../config/deps";
 
 type SupplierSpec = { supplierId: string; specId: string };
@@ -153,33 +154,50 @@ async function runUpsert(
 }
 
 export default function createUpsertLetterHandler(deps: Deps): SQSHandler {
-  return async (event: SQSEvent) => {
-    const batchItemFailures: SQSBatchItemFailure[] = [];
-
-    const tasks = event.Records.map(async (record) => {
-      try {
-        const message: string = parseSNSNotification(record);
-
-        const snsEvent = JSON.parse(message);
-
-        const letterEvent: unknown = removeEventBridgeWrapper(snsEvent);
-
-        const type = getType(letterEvent);
-
-        const operation = getOperationFromType(type);
-
-        await runUpsert(operation, letterEvent, deps);
-      } catch (error) {
-        deps.logger.error(
-          { err: error, message: record.body },
-          `Error processing upsert of record ${record.messageId}`,
-        );
-        batchItemFailures.push({ itemIdentifier: record.messageId });
-      }
-    });
-
-    await Promise.all(tasks);
-
-    return { batchItemFailures };
-  };
+  return metricScope(async (metrics) => {
+    return async (event: SQSEvent) => {
+      const batchItemFailures: SQSBatchItemFailure[] = [];
+
+      const tasks = event.Records.map(async (record) => {
+        try {
+          const message: string = parseSNSNotification(record);
+
+          const snsEvent = JSON.parse(message);
+
+          const letterEvent: unknown = removeEventBridgeWrapper(snsEvent);
+
+          const type = getType(letterEvent);
+
+          const operation = getOperationFromType(type);
+
+          await runUpsert(operation, letterEvent, deps);
+          metrics.putDimensions({
+            FunctionName: "upsertLambda",
+            // eslint-disable-next-line sonarjs/pseudo-random
+            OddOrEven: `${Math.floor(Math.random() * 10) % 2}`,
+            OperationType: operation.name,
+          });
+          metrics.setProperty("operation", operation.name);
+          metrics.putMetric("MessagesProcessed", 1, Unit.Count);
+        } catch (error) {
+          deps.logger.error(
+            { err: error, message: record.body },
+            `Error processing upsert of record ${record.messageId}`,
+          );
+          metrics.putDimensions({
+            FunctionName: "upsertLambda",
+            // eslint-disable-next-line sonarjs/pseudo-random
+            OddOrEven: `${Math.floor(Math.random() * 10) % 2}`,
+          });
+          metrics.setProperty("operation", operation.name);
+          metrics.putMetric("MessageFailed", 1, Unit.Count);
+          batchItemFailures.push({ itemIdentifier: record.messageId });
+        }
+      });
+
+      await Promise.all(tasks);
+
+      return { batchItemFailures };
+    };
+  });
 }