feat: upgrade secrets metric publisher Lambda to Node.js 18 (#417)

Closes #393

Upgrades the second of the two Lambda handlers we have. Manually verified in a test account by manually invoking the Lambda with a valid event (e.g. `{"secretId": "test-secret"}`) and verifying that the metrics were emitted to CloudWatch.

---

_By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license_

assets/SecretsManagerMetricsPublisher/index.js

@@ -1,19 +1,16 @@
-const aws = require("aws-sdk");
+const { CloudWatchClient, PutMetricDataCommand } = require('@aws-sdk/client-cloudwatch');
+const { SecretsManagerClient, DescribeSecretCommand } = require('@aws-sdk/client-secrets-manager');
 
 const region = process.env.AWS_REGION;
 const millisPerDay = 1000 * 60 * 60 * 24;
 
 const clientOptions = {
-    region,
-    maxRetries: 5,
-    httpOptions: {
-        connectTimeout: 3 * 1000,
-        timeout: 3 * 1000,
-    },
+    signingRegion: region,
+    retryMode: 'standard',
 };
 
-const cloudwatch = new aws.CloudWatch(clientOptions);
-const sm = new aws.SecretsManager(clientOptions);
+const cloudwatchClient = new CloudWatchClient(clientOptions);
+const secretsManagerClient = new SecretsManagerClient(clientOptions);
 
 function daysSince(date, now = Date.now()) {
     const millis = now - date.getTime();
@@ -22,19 +19,18 @@ function daysSince(date, now = Date.now()) {
 }
 
 exports.handler = async (event, context) => {
-    console.debug("event:", JSON.stringify(event));
-    console.debug("context:", JSON.stringify(context));
+    console.info(`Retrieving secret for event ${JSON.stringify(event)}`);
+    console.debug(`context: ${JSON.stringify(context)}`);
 
-    console.info(`retrieving secret: ${event.secretId}`);
-    const secret = await sm
-        .describeSecret({
+    const secret = await secretsManagerClient.send(
+        new DescribeSecretCommand({
             SecretId: event.secretId,
         })
-        .promise();
+    );
 
-    console.debug("found secret: ", JSON.stringify(secret));
+    console.debug(`Found secret: ${JSON.stringify(secret)}`);
     if (!secret.Name || !secret.CreatedDate) {
-        throw new Error("invalid secret response");
+        throw new Error("Invalid secret response");
     }
 
     // use retrieved secret name in case secretId was an arn
@@ -43,40 +39,37 @@ exports.handler = async (event, context) => {
     const lastRotatedDate = secret.LastRotatedDate ?? secret.CreatedDate;
     const now = Date.now();
 
-    const metricData = [
-        {
-            MetricName: "DaysSinceLastChange",
-            Dimensions: [
-                {
-                    Name: "SecretName",
-                    Value: secretName,
-                },
-            ],
-            Unit: "Count",
-            Value: daysSince(lastChangedDate, now),
-        },
-        {
-            MetricName: "DaysSinceLastRotation",
-            Dimensions: [
-                {
-                    Name: "SecretName",
-                    Value: secretName,
-                },
-            ],
-            Unit: "Count",
-            Value: daysSince(lastRotatedDate, now),
-        },
-    ];
-
     const params = {
         Namespace: "SecretsManager",
-        MetricData: metricData,
+        MetricData: [
+            {
+                MetricName: "DaysSinceLastChange",
+                Dimensions: [
+                    {
+                        Name: "SecretName",
+                        Value: secretName,
+                    },
+                ],
+                Unit: "Count",
+                Value: daysSince(lastChangedDate, now),
+            },
+            {
+                MetricName: "DaysSinceLastRotation",
+                Dimensions: [
+                    {
+                        Name: "SecretName",
+                        Value: secretName,
+                    },
+                ],
+                Unit: "Count",
+                Value: daysSince(lastRotatedDate, now),
+            },
+        ],
     };
-
-    console.debug("putMetricData params: ", JSON.stringify(params));
-
-    console.info(`publishing metrics for secret: ${event.secretId}`);
-    await cloudwatch.putMetricData(params).promise();
+    console.debug(`putMetricData params: ${JSON.stringify(params)}`);
+    console.info(`Publishing metrics for secret "${event.secretId}"`);
+    const command = new PutMetricDataCommand(params);
+    await cloudwatchClient.send(command);
 
     return Promise.resolve();
 };

lib/monitoring/aws-secretsmanager/SecretsManagerMetricsPublisher.ts

@@ -34,7 +34,7 @@ export class SecretsManagerMetricsPublisher extends Construct {
         "Custom metrics publisher for SecretsManager Secrets (MonitoringCDKConstructs)",
       handler: "index.handler",
       memorySize: 128,
-      runtime: Runtime.NODEJS_14_X,
+      runtime: Runtime.NODEJS_18_X,
       timeout: Duration.seconds(60),
       logRetention: RetentionDays.ONE_DAY,
     });