FIX APIM cert expiry metric

lambdas/authorizer/src/__tests__/index.test.ts

@@ -4,11 +4,30 @@
   Callback,
   Context,
 } from "aws-lambda";
+import { metricScope } from "aws-embedded-metrics";
 import pino from "pino";
 import { Deps } from "../deps";
 import { EnvVars } from "../env";
 import createAuthorizerHandler from "../authorizer";
 
+jest.mock("aws-embedded-metrics", () => {
+  const metricsMock = {
+    setNamespace: jest.fn(),
+    putMetric: jest.fn(),
+  };
+
+  return {
+    metricScope: jest.fn((handler: (metrics: typeof metricsMock) => unknown) => {
+      const wrapped = handler(metricsMock);
+      if (typeof wrapped === "function") {
+        return wrapped();
+      }
+      return undefined;
+    }),
+    __metricsMock: metricsMock,
+  };
+});
+
 const mockedDeps: jest.Mocked<Deps> = {
   logger: {
     info: jest.fn(),
@@ -60,6 +79,17 @@
       jest
         .useFakeTimers({ doNotFake: ["nextTick"] })
         .setSystemTime(new Date("2025-11-03T14:19:00Z"));
+      (metricScope as jest.Mock).mockClear();
+      const metricsMock = (jest.requireMock(
+        "aws-embedded-metrics",
+      ) as {
+        __metricsMock: {
+          setNamespace: jest.Mock;
+          putMetric: jest.Mock;
+        };
+      }).__metricsMock;
+      metricsMock.setNamespace.mockClear();
+      metricsMock.putMetric.mockClear();
     });
 
     afterEach(() => {
@@ -73,10 +103,7 @@
       handler(mockEvent, mockContext, mockCallback);
       await new Promise(process.nextTick);
 
-      const mockedInfo = mockedDeps.logger.info as jest.Mock;
-      expect(mockedInfo.mock.calls).not.toContainEqual(
-        expect.stringContaining("CloudWatchMetrics"),
-      );
+      expect(metricScope).not.toHaveBeenCalled();
     });
 
     it("Should log CloudWatch metric when the certificate expiry threshold is reached", async () => {
@@ -88,29 +115,19 @@
       handler(mockEvent, mockContext, mockCallback);
       await new Promise(process.nextTick);
 
-      const mockedInfo = mockedDeps.logger.info as jest.Mock;
-      expect(mockedInfo.mock.calls.map((call) => call[0])).toContain(
-        JSON.stringify({
-          _aws: {
-            Timestamp: 1_762_179_540_000,
-            CloudWatchMetrics: [
-              {
-                Namespace: "cloudwatch-namespace",
-                Dimensions: ["SUBJECT_DN", "NOT_AFTER"],
-                Metrics: [
-                  {
-                    Name: "apim-client-certificate-near-expiry",
-                    Unit: "Count",
-                    Value: 1,
-                  },
-                ],
-              },
-            ],
-          },
-          SUBJECT_DN: "CN=test-subject",
-          NOT_AFTER: "2025-11-17T14:19:00Z",
-          "apim-client-certificate-near-expiry": 1,
-        }),
+      const metricsMock = (jest.requireMock("aws-embedded-metrics") as {
+        __metricsMock: {
+          setNamespace: jest.Mock;
+          putMetric: jest.Mock;
+        };
+      }).__metricsMock;
+
+      expect(metricScope).toHaveBeenCalledTimes(1);
+      expect(metricsMock.setNamespace).toHaveBeenCalledWith("authorizer");
+      expect(metricsMock.putMetric).toHaveBeenCalledWith(
+        "apim-client-certificate-near-expiry",
+        14,
+        "Count",
       );
     });
 
@@ -123,10 +140,7 @@
       handler(mockEvent, mockContext, mockCallback);
       await new Promise(process.nextTick);
 
-      const mockedInfo = mockedDeps.logger.info as jest.Mock;
-      expect(mockedInfo.mock.calls).not.toContainEqual(
-        expect.stringContaining("CloudWatchMetrics"),
-      );
+      expect(metricScope).not.toHaveBeenCalled();
     });
   });
 

lambdas/authorizer/src/authorizer.ts

@@ -6,7 +6,8 @@ import {
   APIGatewayRequestAuthorizerHandler,
   Callback,
   Context,
-} from "aws-lambda";
+} from "aws-lambda"
+import { MetricsLogger, metricScope } from "aws-embedded-metrics";
 import { Supplier } from "@internal/datastore";
 import { Deps } from "./deps";
 
@@ -100,33 +101,6 @@ function getCertificateExpiryInDays(
   return (expiry - now) / (1000 * 60 * 60 * 24);
 }
 
-function buildCloudWatchMetric(
-  namespace: string,
-  certificate: APIGatewayEventClientCertificate,
-) {
-  return {
-    _aws: {
-      Timestamp: Date.now(),
-      CloudWatchMetrics: [
-        {
-          Namespace: namespace,
-          Dimensions: ["SUBJECT_DN", "NOT_AFTER"],
-          Metrics: [
-            {
-              Name: "apim-client-certificate-near-expiry",
-              Unit: "Count",
-              Value: 1,
-            },
-          ],
-        },
-      ],
-    },
-    SUBJECT_DN: certificate.subjectDN,
-    NOT_AFTER: certificate.validity.notAfter,
-    "apim-client-certificate-near-expiry": 1,
-  };
-}
-
 async function checkCertificateExpiry(
   certificate: APIGatewayEventClientCertificate | null,
   deps: Deps,
@@ -146,10 +120,11 @@ async function checkCertificateExpiry(
   const expiry = getCertificateExpiryInDays(certificate);
 
   if (expiry <= deps.env.CLIENT_CERTIFICATE_EXPIRATION_ALERT_DAYS) {
-    deps.logger.info(
-      JSON.stringify(
-        buildCloudWatchMetric(deps.env.CLOUDWATCH_NAMESPACE, certificate),
-      ),
-    );
-  }
+    metricScope(
+      (metrics: MetricsLogger) => async () => {
+      deps.logger.warn(`APIM Certificated expiry in ${expiry} days`);
+      metrics.setNamespace(process.env.AWS_LAMBDA_FUNCTION_NAME || 'authorizer');
+      metrics.putMetric("apim-client-certificate-near-expiry", expiry, "Count");
+    });
+  };
 }