ECS Scaling at 20% CPU usage.

Author: connoromalleyatwork

dotcom-rendering/cdk/bin/cdk.ts

@@ -1,4 +1,4 @@
-import { App } from 'aws-cdk-lib';
+import { App, Duration } from 'aws-cdk-lib';
 import { InstanceClass, InstanceSize, InstanceType } from 'aws-cdk-lib/aws-ec2';
 import type { RenderingCDKStackProps } from '../lib/renderingStack';
 import { RenderingCDKStack } from '../lib/renderingStack';
@@ -115,6 +115,15 @@ export const TagPageRenderingPropsCODE: RenderingCDKStackProps = {
 		imageIdentifier: getImageIdentifier(),
 		taskCpu: 1024,
 		taskMemoryLimitMiB: 2048,
+		scaling: {
+			minimumTasks: 1,
+			maximumTasks: 9,
+			cpuScaling: {
+				targetValue: 20,
+				scaleInCooldown: Duration.seconds(60),
+				scaleOutCooldown: Duration.seconds(60),
+			},
+		},
 	},
 };
 
@@ -158,6 +167,17 @@ export const TagPageRenderingPropsPROD: RenderingCDKStackProps = {
 		imageIdentifier: getImageIdentifier(),
 		taskCpu: 2048,
 		taskMemoryLimitMiB: 4096,
+		scaling: {
+			minimumTasks: 9,
+			maximumTasks: 90,
+			cpuScaling: {
+				targetValue: 20,
+				// TODO: Tune cooldown values.
+				// https://docs.aws.amazon.com/autoscaling/application/userguide/target-tracking-scaling-policy-overview.html#target-tracking-cooldown
+				scaleInCooldown: Duration.seconds(60),
+				scaleOutCooldown: Duration.seconds(60),
+			},
+		},
 	},
 };
 

dotcom-rendering/cdk/lib/__snapshots__/renderingStack.test.ts.snap

@@ -2109,7 +2109,7 @@ exports[`The RenderingCDKStack matches the snapshot for Tag Page Rendering CODE
         "EcsTaskDefinitionTaskRoleB7B6D8DD",
       ],
       "Properties": {
-        "MaxCapacity": 2,
+        "MaxCapacity": 9,
         "MinCapacity": 1,
         "ResourceId": {
           "Fn::Join": [
@@ -3667,6 +3667,24 @@ systemctl start tag-page-rendering",
       },
       "Type": "AWS::IAM::InstanceProfile",
     },
+    "tagpagerenderingCpuScaling1742C101": {
+      "Properties": {
+        "PolicyName": "TagPageRenderingCODEtagpagerenderingCpuScalingAFEBC723",
+        "PolicyType": "TargetTrackingScaling",
+        "ScalingTargetId": {
+          "Ref": "EcsServiceTaskCountTarget02FCCE22",
+        },
+        "TargetTrackingScalingPolicyConfiguration": {
+          "PredefinedMetricSpecification": {
+            "PredefinedMetricType": "ECSServiceAverageCPUUtilizationHighResolution",
+          },
+          "ScaleInCooldown": 60,
+          "ScaleOutCooldown": 60,
+          "TargetValue": 20,
+        },
+      },
+      "Type": "AWS::ApplicationAutoScaling::ScalingPolicy",
+    },
     "tagpagerenderingEcsClusterE7696595": {
       "Properties": {
         "ClusterSettings": [
@@ -4260,8 +4278,8 @@ exports[`The RenderingCDKStack matches the snapshot for Tag Page Rendering PROD
         "EcsTaskDefinitionTaskRoleB7B6D8DD",
       ],
       "Properties": {
-        "MaxCapacity": 2,
-        "MinCapacity": 1,
+        "MaxCapacity": 90,
+        "MinCapacity": 9,
         "ResourceId": {
           "Fn::Join": [
             "",
@@ -6261,6 +6279,24 @@ systemctl start tag-page-rendering",
       },
       "Type": "AWS::IAM::InstanceProfile",
     },
+    "tagpagerenderingCpuScaling1742C101": {
+      "Properties": {
+        "PolicyName": "TagPageRenderingPRODtagpagerenderingCpuScaling4582D272",
+        "PolicyType": "TargetTrackingScaling",
+        "ScalingTargetId": {
+          "Ref": "EcsServiceTaskCountTarget02FCCE22",
+        },
+        "TargetTrackingScalingPolicyConfiguration": {
+          "PredefinedMetricSpecification": {
+            "PredefinedMetricType": "ECSServiceAverageCPUUtilizationHighResolution",
+          },
+          "ScaleInCooldown": 60,
+          "ScaleOutCooldown": 60,
+          "TargetValue": 20,
+        },
+      },
+      "Type": "AWS::ApplicationAutoScaling::ScalingPolicy",
+    },
     "tagpagerenderingEcsClusterE7696595": {
       "Properties": {
         "ClusterSettings": [

dotcom-rendering/cdk/lib/renderingStack.ts

@@ -8,6 +8,7 @@ import {
 } from '@guardian/cdk/lib/constructs/core';
 import { GuCname } from '@guardian/cdk/lib/constructs/dns/dns-records';
 import { GuAllowPolicy } from '@guardian/cdk/lib/constructs/iam';
+import type { GuLoadBalancedAppExperimentalProps } from '@guardian/cdk/lib/experimental/patterns/gu-load-balanced-app';
 import { GuLoadBalancedAppExperimental } from '@guardian/cdk/lib/experimental/patterns/gu-load-balanced-app';
 import type { GuAsgCapacity } from '@guardian/cdk/lib/types';
 import { aws_cloudwatch, type App as CDKApp, Duration } from 'aws-cdk-lib';
@@ -67,6 +68,10 @@ export interface RenderingCDKStackProps extends Omit<GuStackProps, 'stack'> {
 		 * Memory in MB for ECS task
 		 */
 		taskMemoryLimitMiB: number;
+
+		scaling: NonNullable<
+			GuLoadBalancedAppExperimentalProps['ecsProps']
+		>['scaling'];
 	};
 }
 
@@ -296,10 +301,7 @@ export class RenderingCDKStack extends CDKStack {
 
 							memoryLimitMiB: ecsProps.taskMemoryLimitMiB,
 							cpu: ecsProps.taskCpu,
-							scaling: {
-								minimumTasks: 1,
-								maximumTasks: 2,
-							},
+							scaling: ecsProps.scaling,
 						},
 
 						// Route all traffic to EC2
@@ -312,7 +314,6 @@ export class RenderingCDKStack extends CDKStack {
 
 		if (app.ecsService) {
 			const { taskDefinition } = app.ecsService;
-
 			const ecsEnvVars: Record<string, string> = {
 				// Custom environment variables needed by the application
 				NODE_ENV: 'production',