chore(autoscaling): add lowest-price OnDemandAllocationStrategy enum …

…to aws-autoscaling (#28396)

Closes #28395

Adds the On-Demand `lowest-price` allocation strategy enum for aws-autoscaling. 

https://docs.aws.amazon.com/autoscaling/ec2/userguide/allocation-strategies.html#on-demand-allocation-strategy

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

packages/aws-cdk-lib/aws-autoscaling/lib/auto-scaling-group.ts

@@ -429,6 +429,15 @@ export enum OnDemandAllocationStrategy {
    * so on.
    */
   PRIORITIZED = 'prioritized',
+
+  /**
+   * This strategy uses the lowest-price instance types in each Availability Zone based on the current
+   * On-Demand instance price.
+   *
+   * To meet your desired capacity, you might receive On-Demand Instances of more than one instance type
+   * in each Availability Zone. This depends on how much capacity you request.
+   */
+  LOWEST_PRICE = 'lowest-price',
 }
 
 /**

packages/aws-cdk-lib/aws-autoscaling/test/auto-scaling-group.test.ts

@@ -2277,6 +2277,43 @@ test('add price-capacity-optimized', () => {
   });
 });
 
+test('add on-demand lowest-price allocation strategy', () => {
+  // GIVEN
+  const stack = new cdk.Stack();
+
+  // WHEN
+  const lt = LaunchTemplate.fromLaunchTemplateAttributes(stack, 'imported-lt', {
+    launchTemplateId: 'test-lt-id',
+    versionNumber: '0',
+  });
+
+  new autoscaling.AutoScalingGroup(stack, 'mip-asg', {
+    mixedInstancesPolicy: {
+      launchTemplate: lt,
+      launchTemplateOverrides: [{
+        instanceType: new InstanceType('t4g.micro'),
+        launchTemplate: lt,
+        weightedCapacity: 9,
+      }],
+      instancesDistribution: {
+        onDemandAllocationStrategy: OnDemandAllocationStrategy.LOWEST_PRICE,
+        onDemandBaseCapacity: 1,
+        onDemandPercentageAboveBaseCapacity: 100,
+      },
+    },
+    vpc: mockVpc(stack),
+  });
+
+  // THEN
+  Template.fromStack(stack).hasResourceProperties('AWS::AutoScaling::AutoScalingGroup', {
+    MixedInstancesPolicy: {
+      InstancesDistribution: {
+        OnDemandAllocationStrategy: 'lowest-price',
+      },
+    },
+  });
+});
+
 test('ssm permissions adds right managed policy', () => {
   // GIVEN
   const stack = new cdk.Stack();