refactor(report): Simplify low 2XX alarm creation

Loop over a list of alarm configurations to keep DRY.

Author: akash1810

cdk/bin/cdk.ts

@@ -1,5 +1,5 @@
 import 'source-map-support/register';
-import { App } from 'aws-cdk-lib';
+import { App, Duration } from 'aws-cdk-lib';
 import type { NotificationProps } from '../lib/notification';
 import { Notification } from '../lib/notification';
 import type { RegistrationProps } from '../lib/registration';
@@ -31,8 +31,10 @@ export const registrationCodeProps: RegistrationProps = {
 	env: { region: 'eu-west-1' },
 	instanceMetricGranularity: '5Minute',
 	minAsgSize: 0,
-	low2xxIn30MinutesThreshold: 0,
-	low2xxIn24HoursThreshold: 1,
+	low2xxAlarmConfiguration: [
+		{ period: Duration.minutes(30), threshold: 0 },
+		{ period: Duration.hours(24), threshold: 1 },
+	],
 	cloudFormationStackName: 'mobile-notifications-registration-CODE',
 };
 
@@ -44,8 +46,10 @@ export const registrationProdProps: RegistrationProps = {
 	instanceMetricGranularity: '1Minute',
 	maxAsgSize: 0,
 	minAsgSize: 0,
-	low2xxIn30MinutesThreshold: 1_000,
-	low2xxIn24HoursThreshold: 150_000,
+	low2xxAlarmConfiguration: [
+		{ period: Duration.minutes(30), threshold: 1_000 },
+		{ period: Duration.hours(24), threshold: 150_000 },
+	],
 	cloudFormationStackName: 'mobile-notifications-registration-PROD',
 };
 

cdk/lib/__snapshots__/registration.test.ts.snap

@@ -1122,7 +1122,7 @@ exports[`The Registration stack matches the snapshot for CODE 1`] = `
       },
       "Type": "AWS::ElasticLoadBalancing::LoadBalancer",
     },
-    "Low2XXIn24Hours04FC9138": {
+    "Low2XXIn1dayE630C03B": {
       "Properties": {
         "ActionsEnabled": false,
         "AlarmActions": [
@@ -1139,7 +1139,7 @@ exports[`The Registration stack matches the snapshot for CODE 1`] = `
             ],
           },
         ],
-        "AlarmDescription": "Triggers if load balancer in CODE does not have enough 200s in a whole day. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
+        "AlarmDescription": "Triggers if load balancer in CODE does not have enough 200s in 1 day. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
         "ComparisonOperator": "LessThanThreshold",
         "Dimensions": [
           {
@@ -1198,7 +1198,7 @@ exports[`The Registration stack matches the snapshot for CODE 1`] = `
       },
       "Type": "AWS::CloudWatch::Alarm",
     },
-    "Low2XXIn30Minutes4275AF7F": {
+    "Low2XXIn30minutesE2E53BDD": {
       "Properties": {
         "ActionsEnabled": false,
         "AlarmActions": [
@@ -1215,7 +1215,7 @@ exports[`The Registration stack matches the snapshot for CODE 1`] = `
             ],
           },
         ],
-        "AlarmDescription": "Triggers if load balancer in CODE does not have enough 200s in half an hour. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
+        "AlarmDescription": "Triggers if load balancer in CODE does not have enough 200s in 30 minutes. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
         "ComparisonOperator": "LessThanThreshold",
         "Dimensions": [
           {
@@ -3055,7 +3055,7 @@ exports[`The Registration stack matches the snapshot for PROD 1`] = `
       },
       "Type": "AWS::ElasticLoadBalancing::LoadBalancer",
     },
-    "Low2XXIn24Hours04FC9138": {
+    "Low2XXIn1dayE630C03B": {
       "Properties": {
         "ActionsEnabled": false,
         "AlarmActions": [
@@ -3072,7 +3072,7 @@ exports[`The Registration stack matches the snapshot for PROD 1`] = `
             ],
           },
         ],
-        "AlarmDescription": "Triggers if load balancer in PROD does not have enough 200s in a whole day. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
+        "AlarmDescription": "Triggers if load balancer in PROD does not have enough 200s in 1 day. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
         "ComparisonOperator": "LessThanThreshold",
         "Dimensions": [
           {
@@ -3131,7 +3131,7 @@ exports[`The Registration stack matches the snapshot for PROD 1`] = `
       },
       "Type": "AWS::CloudWatch::Alarm",
     },
-    "Low2XXIn30Minutes4275AF7F": {
+    "Low2XXIn30minutesE2E53BDD": {
       "Properties": {
         "ActionsEnabled": false,
         "AlarmActions": [
@@ -3148,7 +3148,7 @@ exports[`The Registration stack matches the snapshot for PROD 1`] = `
             ],
           },
         ],
-        "AlarmDescription": "Triggers if load balancer in PROD does not have enough 200s in half an hour. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
+        "AlarmDescription": "Triggers if load balancer in PROD does not have enough 200s in 30 minutes. <<<Runbook|https://docs.google.com/document/d/1aJMytnPGeWH8YLpD2_66doxqyr8dPvAVonYIOG-zmOA>>>",
         "ComparisonOperator": "LessThanThreshold",
         "Dimensions": [
           {

cdk/lib/registration.ts

@@ -4,7 +4,8 @@ import { AccessScope } from '@guardian/cdk/lib/constants';
 import type { GuStackProps } from '@guardian/cdk/lib/constructs/core';
 import { GuStack, GuStringParameter } from '@guardian/cdk/lib/constructs/core';
 import { GuAllowPolicy } from '@guardian/cdk/lib/constructs/iam';
-import { type App, Duration, Tags } from 'aws-cdk-lib';
+import type { Duration } from 'aws-cdk-lib';
+import { type App, Tags } from 'aws-cdk-lib';
 import {
 	ComparisonOperator,
 	TreatMissingData,
@@ -26,8 +27,7 @@ export interface RegistrationProps extends GuStackProps {
 	instanceMetricGranularity: '1Minute' | '5Minute';
 	minAsgSize: number;
 	maxAsgSize?: number;
-	low2xxIn30MinutesThreshold: number;
-	low2xxIn24HoursThreshold: number;
+	low2xxAlarmConfiguration: Array<{ period: Duration; threshold: number }>;
 }
 
 export class Registration extends GuStack {
@@ -51,8 +51,7 @@ export class Registration extends GuStack {
 			instanceMetricGranularity,
 			minAsgSize,
 			maxAsgSize,
-			low2xxIn30MinutesThreshold,
-			low2xxIn24HoursThreshold,
+			low2xxAlarmConfiguration,
 		} = props;
 
 		const { account, region } = this;
@@ -134,39 +133,25 @@ export class Registration extends GuStack {
 		);
 		const snsAction = new SnsAction(alarmTopic);
 
-		const low2xxIn30Minutes = loadBalancer.metrics
-			.httpCodeTarget(HttpCodeTarget.TARGET_2XX_COUNT, {
-				period: Duration.minutes(30),
-				statistic: 'Sum',
-			})
-			.createAlarm(this, 'Low2XXIn30Minutes', {
-				actionsEnabled: false,
-				alarmDescription: `Triggers if load balancer in ${stage} does not have enough 200s in half an hour. ${runbookCopy}`,
-				comparisonOperator: ComparisonOperator.LESS_THAN_THRESHOLD,
-				evaluationPeriods: 1,
-				threshold: low2xxIn30MinutesThreshold,
-				treatMissingData: TreatMissingData.BREACHING,
-			});
-
-		low2xxIn30Minutes.addAlarmAction(snsAction);
-		low2xxIn30Minutes.addOkAction(snsAction);
-
-		const low2xxIn24Hours = loadBalancer.metrics
-			.httpCodeTarget(HttpCodeTarget.TARGET_2XX_COUNT, {
-				period: Duration.hours(24),
-				statistic: 'Sum',
-			})
-			.createAlarm(this, 'Low2XXIn24Hours', {
-				actionsEnabled: false,
-				alarmDescription: `Triggers if load balancer in ${stage} does not have enough 200s in a whole day. ${runbookCopy}`,
-				comparisonOperator: ComparisonOperator.LESS_THAN_THRESHOLD,
-				evaluationPeriods: 1,
-				threshold: low2xxIn24HoursThreshold,
-				treatMissingData: TreatMissingData.BREACHING,
-			});
-
-		low2xxIn24Hours.addAlarmAction(snsAction);
-		low2xxIn24Hours.addOkAction(snsAction);
+		low2xxAlarmConfiguration.forEach(({ period, threshold }) => {
+			const humanPeriod = period.toHumanString();
+			const alarm = loadBalancer.metrics
+				.httpCodeTarget(HttpCodeTarget.TARGET_2XX_COUNT, {
+					period,
+					statistic: 'Sum',
+				})
+				.createAlarm(this, `Low2XXIn${humanPeriod}`, {
+					actionsEnabled: false,
+					alarmDescription: `Triggers if load balancer in ${stage} does not have enough 200s in ${humanPeriod}. ${runbookCopy}`,
+					comparisonOperator: ComparisonOperator.LESS_THAN_THRESHOLD,
+					evaluationPeriods: 1,
+					threshold,
+					treatMissingData: TreatMissingData.BREACHING,
+				});
+
+			alarm.addAlarmAction(snsAction);
+			alarm.addOkAction(snsAction);
+		});
 
 		adjustCloudformationParameters(this);
 	}