Backend5xxAlarm.ts

Backend5xxAlarm.ts

import { GuAlarm, GuStack } from '@guardian/cdk';
import { Metric, ComparisonOperator } from '@aws-cdk/aws-cloudwatch';

const Backend5XXAlarmThreshold = 100;
const Backend5XXAlarmPeriod = 1;
const Backend5XXConsecutivePeriod = 5;

const criticalAlertsTopic = sns.Topic.fromTopicArn(this, 'CriticalAlertsTopic', 'arn:aws:sns:<region>:<account-id>:Frontend-PROD-CriticalAlerts'); // modify to CODE in the meantime? I don't think we have one for CODE, so we may need to set this up

const alarm = new GuAlarm(stack, 'Backend5xxAlarm', {
  app: 'rendering',
  stack: 'frontend',
  stage: stack.stage,
  metric: new Metric({
    namespace: 'AWS/ELB',
    metricName: 'HTTPCode_Backend_5XX',
    dimensions: { LoadBalancerName: lb.InternalLoadBalancer },
    statistic: 'Sum',
    period: cdk.Duration.minutes(Backend5XXAlarmPeriod),
  }),
  alarmDescription: `Alarm if 5XX backend errors are greater than ${Backend5XXAlarmThreshold} over last ${Backend5XXAlarmPeriod} seconds`,
  threshold: Backend5XXAlarmThreshold,
  evaluationPeriods: Backend5XXConsecutivePeriod,
  comparisonOperator: ComparisonOperator.GREATER_THAN_THRESHOLD,
  alarmActions: [criticalAlertsTopic.topicArn], // Placeholder - default is set to '', but in AWS, it shows SNS topic
  okActions: [criticalAlertsTopic.topicArn], // Placeholder - default is set to '', but in AWS, it shows SNS topic
});