fix(eks): impossible to define multiple spot capacities

Install only a single instance of the spot termination handler helm chart, even if there are multiple capacities or ASGs the use spot instances.

Fixes #7136
Fixes #7524

packages/@aws-cdk/aws-eks/lib/cluster.ts

@@ -342,6 +342,8 @@ export class Cluster extends Resource implements ICluster {
    */
   private _awsAuth?: AwsAuth;
 
+  private _spotInterruptHandler?: HelmChart;
+
   private readonly version: string | undefined;
 
   /**
@@ -596,15 +598,7 @@ export class Cluster extends Resource implements ICluster {
 
     // if this is an ASG with spot instances, install the spot interrupt handler (only if kubectl is enabled).
     if (autoScalingGroup.spotPrice && this.kubectlEnabled) {
-      this.addChart('spot-interrupt-handler', {
-        chart: 'aws-node-termination-handler',
-        version: '0.7.3',
-        repository: 'https://aws.github.io/eks-charts',
-        namespace: 'kube-system',
-        values: {
-          'nodeSelector.lifecycle': LifecycleLabel.SPOT,
-        },
-      });
+      this.addSpotInterruptHandler();
     }
   }
 
@@ -692,6 +686,26 @@ export class Cluster extends Resource implements ICluster {
     return this.stack.node.tryFindChild(uid) as KubectlProvider || new KubectlProvider(this.stack, uid);
   }
 
+  /**
+   * Installs the AWS spot instance interrupt handler on the cluster if it's not
+   * already added.
+   */
+  private addSpotInterruptHandler() {
+    if (!this._spotInterruptHandler) {
+      this._spotInterruptHandler = this.addChart('spot-interrupt-handler', {
+        chart: 'aws-node-termination-handler',
+        version: '0.7.3',
+        repository: 'https://aws.github.io/eks-charts',
+        namespace: 'kube-system',
+        values: {
+          'nodeSelector.lifecycle': LifecycleLabel.SPOT,
+        },
+      });
+    }
+
+    return this._spotInterruptHandler;
+  }
+
   /**
    * Opportunistically tag subnets with the required tags.
    *

packages/@aws-cdk/aws-eks/test/test.cluster.ts

@@ -1,4 +1,4 @@
-import { expect, haveResource, haveResourceLike, not } from '@aws-cdk/assert';
+import { countResources, expect, haveResource, haveResourceLike, not } from '@aws-cdk/assert';
 import * as ec2 from '@aws-cdk/aws-ec2';
 import * as iam from '@aws-cdk/aws-iam';
 import * as cdk from '@aws-cdk/core';
@@ -665,13 +665,13 @@ export = {
         },
 
         'if kubectl is enabled, the interrupt handler is added'(test: Test) {
-        // GIVEN
+          // GIVEN
           const { stack } = testFixtureNoVpc();
           const cluster = new eks.Cluster(stack, 'Cluster', { defaultCapacity: 0 });
 
           // WHEN
           cluster.addCapacity('MyCapcity', {
-            instanceType: new ec2.InstanceType('m3.xlargs'),
+            instanceType: new ec2.InstanceType('m3.xlarge'),
             spotPrice: '0.01',
           });
 
@@ -687,6 +687,27 @@ export = {
           test.done();
         },
 
+        'its possible to add two capacities with spot instances and only one stop handler will be installed'(test: Test) {
+          // GIVEN
+          const { stack } = testFixtureNoVpc();
+          const cluster = new eks.Cluster(stack, 'Cluster', { defaultCapacity: 0 });
+
+          // WHEN
+          cluster.addCapacity('Spot1', {
+            instanceType: new ec2.InstanceType('m3.xlarge'),
+            spotPrice: '0.01',
+          });
+
+          cluster.addCapacity('Spot2', {
+            instanceType: new ec2.InstanceType('m4.xlarge'),
+            spotPrice: '0.01',
+          });
+
+          // THEN
+          expect(stack).to(countResources(eks.HelmChart.RESOURCE_TYPE, 1));
+          test.done();
+        },
+
         'if kubectl is disabled, interrupt handler is not added'(test: Test) {
         // GIVEN
           const { stack } = testFixtureNoVpc();