fix(aws-eks): Allow desiredsize minsize and maxsize to accept CfnPara…

…meters. (aws#15487)

----
Added logic similar to AutoscalngGroup    module to allow EKS NodeGroups to accept CfnParameters for desiredsize minsize and maxsize as CfnParameter.valueAsNumber. 

Helps with issue aws#15485
*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/@aws-cdk/aws-eks/lib/managed-nodegroup.ts

@@ -1,6 +1,6 @@
 import { InstanceType, ISecurityGroup, SubnetSelection } from '@aws-cdk/aws-ec2';
 import { IRole, ManagedPolicy, Role, ServicePrincipal } from '@aws-cdk/aws-iam';
-import { IResource, Resource, Annotations } from '@aws-cdk/core';
+import { IResource, Resource, Annotations, withResolved } from '@aws-cdk/core';
 import { Construct } from 'constructs';
 import { Cluster, ICluster } from './cluster';
 import { CfnNodegroup } from './eks.generated';
@@ -321,12 +321,19 @@ export class Nodegroup extends Resource implements INodegroup {
     this.maxSize = props.maxSize ?? this.desiredSize;
     this.minSize = props.minSize ?? 1;
 
-    if (this.desiredSize > this.maxSize) {
-      throw new Error(`Desired capacity ${this.desiredSize} can't be greater than max size ${this.maxSize}`);
-    }
-    if (this.desiredSize < this.minSize) {
-      throw new Error(`Minimum capacity ${this.minSize} can't be greater than desired size ${this.desiredSize}`);
-    }
+    withResolved(this.desiredSize, this.maxSize, (desired, max) => {
+      if (desired === undefined) {return ;}
+      if (desired > max) {
+        throw new Error(`Desired capacity ${desired} can't be greater than max size ${max}`);
+      }
+    });
+
+    withResolved(this.desiredSize, this.minSize, (desired, min) => {
+      if (desired === undefined) {return ;}
+      if (desired < min) {
+        throw new Error(`Minimum capacity ${min} can't be greater than desired size ${desired}`);
+      }
+    });
 
     if (props.launchTemplateSpec && props.diskSize) {
       // see - https://docs.aws.amazon.com/eks/latest/userguide/launch-templates.html

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

@@ -598,6 +598,58 @@ export = {
     test.throws(() => cluster.addNodegroupCapacity('ng', { desiredSize: 2, minSize: 3 }), /Minimum capacity 3 can't be greater than desired size 2/);
     test.done();
   },
+  'can set minSize , maxSize and DesiredSize'(test: Test) {
+    // GIVEN
+    const { stack, vpc } = testFixture();
+    const cluster = new eks.Cluster(stack, 'Cluster', {
+      vpc,
+      defaultCapacity: 0,
+      version: CLUSTER_VERSION,
+    });
+    // WHEN
+    new eks.Nodegroup(stack, 'NodeGroup', {
+      cluster: cluster,
+      minSize: 2,
+      maxSize: 6,
+      desiredSize: 4,
+    });
+    // THEN
+    expect(stack).to(haveResourceLike('AWS::EKS::Nodegroup', {
+      ScalingConfig: {
+        MinSize: 2,
+        MaxSize: 6,
+        DesiredSize: 4,
+      },
+    },
+    ));
+    test.done();
+  },
+  'validation is not performed when using Tokens'(test: Test) {
+    // GIVEN
+    const { stack, vpc } = testFixture();
+    const cluster = new eks.Cluster(stack, 'Cluster', {
+      vpc,
+      defaultCapacity: 0,
+      version: CLUSTER_VERSION,
+    });
+    // WHEN
+    new eks.Nodegroup(stack, 'NodeGroup', {
+      cluster: cluster,
+      minSize: cdk.Lazy.number({ produce: () => 5 }),
+      maxSize: cdk.Lazy.number({ produce: () => 1 }),
+      desiredSize: cdk.Lazy.number({ produce: () => 20 }),
+    });
+    // THEN
+    expect(stack).to(haveResourceLike('AWS::EKS::Nodegroup', {
+      ScalingConfig: {
+        MinSize: 5,
+        MaxSize: 1,
+        DesiredSize: 20,
+      },
+    },
+    ));
+    test.done();
+  },
   'create nodegroup correctly with launch template'(test: Test) {
     // GIVEN
     const { stack, vpc } = testFixture();