Skip to content

feat: Configure OK action for unhealthy instances alarm #1166

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
akash1810 merged 1 commit into from
Aug 25, 2026
+38 −2
Merged

feat: Configure OK action for unhealthy instances alarm #1166

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 14 additions & 0 deletions cdk/lib/__snapshots__/prism.test.ts.snap
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1011,6 +1011,20 @@ exports[`The PrismEc2App stack matches the snapshot 1`] = `
"EvaluationPeriods": 60,
"MetricName": "UnHealthyHostCount",
"Namespace": "AWS/ApplicationELB",
"OKActions": [
{
"Fn::Join": [
"",
[
"arn:aws:sns:eu-west-1:",
{
"Ref": "AWS::AccountId",
},
":devx-alerts",
],
],
},
],
"Period": 60,
"Statistic": "Maximum",
"Tags": [
Expand Down
26 changes: 24 additions & 2 deletions cdk/lib/prism.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
import { AccessScope } from '@guardian/cdk/lib/constants';
import { GuUnhealthyInstancesAlarm } from '@guardian/cdk/lib/constructs/cloudwatch';
import {
GuDistributionBucketParameter,
GuPrivateConfigBucketParameter,
Expand All @@ -18,6 +19,7 @@ import {
BlockDeviceVolume,
EbsDeviceVolumeType,
} from 'aws-cdk-lib/aws-autoscaling';
import { SnsAction } from 'aws-cdk-lib/aws-cloudwatch-actions';
import {
InstanceClass,
InstanceSize,
Expand All @@ -26,6 +28,7 @@ import {
UserData,
} from 'aws-cdk-lib/aws-ec2';
import { Bucket } from 'aws-cdk-lib/aws-s3';
import { Topic } from 'aws-cdk-lib/aws-sns';

interface PrismProps extends Omit<GuStackProps, 'description' | 'stack'> {
domainName: string;
Expand All @@ -51,7 +54,8 @@ export class Prism extends GuStack {
});

const { buildIdentifier, instanceMetricGranularity } = props;
const { stack, stage } = this;
const { stack, stage, region, account } = this;
const snsTopicName = 'devx-alerts';

const distBucket = Bucket.fromBucketName(
this,
Expand Down Expand Up @@ -98,7 +102,7 @@ export class Prism extends GuStack {
monitoringConfiguration:
this.stage === 'PROD'
? {
snsTopicName: 'devx-alerts',
snsTopicName,
http5xxAlarm: false,
unhealthyInstancesAlarm: true,
}
Expand Down Expand Up @@ -154,5 +158,23 @@ export class Prism extends GuStack {
const cfnAsg = pattern.autoScalingGroup.node
.defaultChild as CfnAutoScalingGroup;
cfnAsg.healthCheckGracePeriod = Duration.minutes(15).toSeconds();

// Configure OK action to receive a notification once alarm has resolved.
// TODO Set the OK action at the construct level within GuCDK
const maybeUnhealthyInstanceAlarm = this.node.children.filter(
(child): child is GuUnhealthyInstancesAlarm =>
child instanceof GuUnhealthyInstancesAlarm,
);
if (maybeUnhealthyInstanceAlarm.length > 0) {
const snsTopic = Topic.fromTopicArn(
this,
`SnsTopic`,
`arn:aws:sns:${region}:${account}:${snsTopicName}`,
);

maybeUnhealthyInstanceAlarm.forEach((alarm) => {
alarm.addOkAction(new SnsAction(snsTopic));
});
}
}
}