monitoring

CloudWatch Monitoring

Overview

Add CloudWatch Alarms for Lambda errors, throttles, duration, SQS queue depth, and DynamoDB throttles. Notify via SNS for critical failures. Use CDK to define alarms and optional dashboards.

Lambda Alarms

// cdk/lib/stacks/monitoring-stack.ts

import { Stack, StackProps, Duration } from "aws-cdk-lib";
import { Construct } from "constructs";
import {
  Alarm,
  ComparisonOperator,
  TreatMissingData,
  Stats,
} from "aws-cdk-lib/aws-cloudwatch";
import { SnsAction } from "aws-cdk-lib/aws-cloudwatch-actions";
import { Topic } from "aws-cdk-lib/aws-sns";
import { Function as LambdaFunction } from "aws-cdk-lib/aws-lambda";

interface MonitoringStackProps extends StackProps {
  lambdaFunctions: LambdaFunction[];
  alarmTopic?: Topic;
}

export class MonitoringStack extends Stack {
  constructor(scope: Construct, id: string, props: MonitoringStackProps) {
    super(scope, id, props);

    const alarmTopic =
      props.alarmTopic ??
      new Topic(this, "AlarmTopic", { displayName: "Real Estate Alarms" });

    for (const fn of props.lambdaFunctions) {
      new Alarm(this, `${fn.node.id}Errors`, {
        alarmName: `${fn.functionName}-errors`,
        metric: fn.metricErrors({ period: Duration.minutes(1) }),
        threshold: 5,
        evaluationPeriods: 1,
        comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
        treatMissingData: TreatMissingData.NOT_BREACHING,
      }).addAlarmAction(new SnsAction(alarmTopic));

      new Alarm(this, `${fn.node.id}Throttles`, {
        alarmName: `${fn.functionName}-throttles`,
        metric: fn.metricThrottles({ period: Duration.minutes(1) }),
        threshold: 1,
        evaluationPeriods: 1,
        comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
        treatMissingData: TreatMissingData.NOT_BREACHING,
      }).addAlarmAction(new SnsAction(alarmTopic));

      const timeoutMs = fn.timeout?.toMilliseconds() ?? 30000;
      new Alarm(this, `${fn.node.id}Duration`, {
        alarmName: `${fn.functionName}-duration`,
        metric: fn.metricDuration({ period: Duration.minutes(1), statistic: Stats.P99 }),
        threshold: timeoutMs * 0.8,
        evaluationPeriods: 2,
        comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
        treatMissingData: TreatMissingData.NOT_BREACHING,
      }).addAlarmAction(new SnsAction(alarmTopic));
    }
  }
}