Use common metrics code and fix bug (#433)

* Use common metrics code and fix bug

* Fix tests

* Fix linting order

Author: stevebux

lambdas/update-letter-queue/src/__tests__/update-letter-queue.test.ts

@@ -5,12 +5,14 @@ import {
 } from "@internal/datastore";
 import { mockDeep } from "jest-mock-extended";
 import pino from "pino";
+import { MetricStatus } from "@internal/helpers";
 import {
   Context,
   DynamoDBRecord,
   KinesisStreamEvent,
   KinesisStreamRecordPayload,
 } from "aws-lambda";
+import { Unit } from "aws-embedded-metrics";
 import { Deps } from "../deps";
 import createHandler from "../update-letter-queue";
 import { EnvVars } from "../env";
@@ -301,13 +303,14 @@ function assertSuccessMetricLogged(count: number) {
           expect.objectContaining({
             Metrics: [
               expect.objectContaining({
-                Name: "letters queued successfully",
+                Name: MetricStatus.Success,
                 Value: count,
               }),
             ],
           }),
         ]),
       }),
+      success: count,
     }),
   );
 }
@@ -320,13 +323,15 @@ function assertFailureMetricLogged(count: number) {
           expect.objectContaining({
             Metrics: [
               expect.objectContaining({
-                Name: "letters queued failed",
+                Name: MetricStatus.Failure,
                 Value: count,
+                Unit: Unit.Count,
               }),
             ],
           }),
         ]),
       }),
+      failure: count,
     }),
   );
 }

lambdas/update-letter-queue/src/update-letter-queue.ts

@@ -6,6 +6,7 @@ import {
 } from "aws-lambda";
 import { unmarshall } from "@aws-sdk/util-dynamodb";
 import { Unit } from "aws-embedded-metrics";
+import { MetricStatus, buildEMFObject } from "@internal/helpers";
 import {
   InsertPendingLetter,
   Letter,
@@ -82,8 +83,8 @@ function recordProcessing(
     totalProcessed: successCount + failureCount,
   });
 
-  deps.logger.info(buildMetric("letters queued successfully", successCount));
-  deps.logger.info(buildMetric("letters queued failed", failureCount));
+  deps.logger.info(buildMetric(MetricStatus.Success, successCount));
+  deps.logger.info(buildMetric(MetricStatus.Failure, failureCount));
 }
 
 function isNewPendingLetter(record: DynamoDBRecord): boolean {
@@ -135,22 +136,14 @@ function mapLetterToPendingLetter(letter: Letter): InsertPendingLetter {
   };
 }
 
-function buildMetric(name: string, count: number) {
-  const namespace =
-    process.env.AWS_LAMBDA_FUNCTION_NAME || "update-letter-queue";
-  return {
-    LogGroup: namespace,
-    ServiceName: namespace,
-    _aws: {
-      Timestamp: Date.now(),
-      CloudWatchMetrics: [
-        {
-          Namespace: namespace,
-          Dimensions: [["ServiceName", "LogGroup"]],
-          Metrics: [{ Name: name, Value: count, Unit: Unit.Count }],
-        },
-      ],
+function buildMetric(status: MetricStatus, count: number) {
+  return buildEMFObject(
+    "update-letter-queue",
+    {},
+    {
+      key: status,
+      value: count,
+      unit: Unit.Count,
     },
-    "events published": count,
-  };
+  );
 }