Add CloudWatch notifications and SNS subscriptions

cdk/lib/app-stack.ts

@@ -6,9 +6,12 @@ import type { Construct } from "constructs";
 import * as ecs from "aws-cdk-lib/aws-ecs";
 import * as ecsPatterns from "aws-cdk-lib/aws-ecs-patterns";
 import * as ecrAssets from "aws-cdk-lib/aws-ecr-assets";
+import * as cloudwatch from "aws-cdk-lib/aws-cloudwatch";
 import * as logs from "aws-cdk-lib/aws-logs";
 import * as ssm from "aws-cdk-lib/aws-ssm";
+import * as sns from "aws-cdk-lib/aws-sns";
 import * as iam from "aws-cdk-lib/aws-iam";
+import * as snsSubscriptions from "aws-cdk-lib/aws-sns-subscriptions";
 
 interface Props extends cdk.StackProps {
   bucket: cdk.aws_s3.Bucket;
@@ -202,5 +205,29 @@ export class AppStack extends cdk.Stack {
     );
 
     this.loadbalancer = fargateService.loadBalancer;
+
+    // Cloudwatch notifications
+    const alarm = new cloudwatch.Alarm(this, "FargateServiceDownAlarm", {
+      alarmName: "FargateServiceDownAlarm",
+      alarmDescription: "Triggered when Fargate service is down",
+      metric: fargateService.service.metricCpuUtilization(),
+      threshold: 10,
+      evaluationPeriods: 1,
+      comparisonOperator: cloudwatch.ComparisonOperator.LESS_THAN_THRESHOLD,
+      treatMissingData: cloudwatch.TreatMissingData.NOT_BREACHING,
+    });
+
+    const snsTopic = new sns.Topic(this, "FargateServiceAlertTopic");
+    alarm.addAlarmAction(new cdk.aws_cloudwatch_actions.SnsAction(snsTopic));
+
+    snsTopic.addSubscription(
+      new snsSubscriptions.EmailSubscription(
+        ssm.StringParameter.fromStringParameterName(
+          this,
+          "alertEmail",
+          "/env/alertEmail",
+        ).toString(),
+      ),
+    );
   }
 }