refactor(sagemaker): address latest PR review feedback

- Remove redundant hasInstanceVariants variable in validation logic
- Add SageMaker Serverless Inference documentation link to README
- Throw error in renderServerlessProductionVariant when undefined
- Add validation in renderInstanceProductionVariants for empty variants
- Add comprehensive API assertions to integration tests
- Update integration test snapshots

Addresses review comments from abidhasan-aws in PR #35557

Author: Mia Chang

packages/@aws-cdk/aws-sagemaker-alpha/README.md

@@ -216,7 +216,7 @@ const endpointConfig = new sagemaker.EndpointConfig(this, 'EndpointConfig', {
 
 ### Serverless Inference
 
-Amazon SageMaker Serverless Inference is a purpose-built inference option that makes it easy for you to deploy and scale ML models. Serverless endpoints automatically launch compute resources and scale them in and out depending on traffic, eliminating the need to choose instance types or manage scaling policies.
+Amazon SageMaker Serverless Inference is a purpose-built inference option that makes it easy for you to deploy and scale ML models. Serverless endpoints automatically launch compute resources and scale them in and out depending on traffic, eliminating the need to choose instance types or manage scaling policies. For more information, see [SageMaker Serverless Inference](https://docs.aws.amazon.com/sagemaker/latest/dg/serverless-endpoints.html).
 
 To create a serverless endpoint configuration, use the `serverlessProductionVariant` property:
 

packages/@aws-cdk/aws-sagemaker-alpha/lib/endpoint-config.ts

@@ -370,21 +370,20 @@ export class EndpointConfig extends cdk.Resource implements IEndpointConfig {
   }
 
   private validateProductionVariants(): void {
-    const hasInstanceVariants = this._instanceProductionVariants.length > 0;
     const hasServerlessVariant = this.serverlessProductionVariant !== undefined;
 
     // validate at least one production variant
-    if (!hasInstanceVariants && !hasServerlessVariant) {
+    if (this._instanceProductionVariants.length === 0 && !hasServerlessVariant) {
       throw new Error('Must configure at least 1 production variant');
     }
 
     // validate mutual exclusivity
-    if (hasInstanceVariants && hasServerlessVariant) {
+    if (this._instanceProductionVariants.length > 0 && hasServerlessVariant) {
       throw new Error('Cannot configure both instance and serverless production variants');
     }
 
     // validate instance variant limits
-    if (hasInstanceVariants && this._instanceProductionVariants.length > 10) {
+    if (this._instanceProductionVariants.length > 10) {
       throw new Error('Can\'t have more than 10 production variants');
     }
   }
@@ -474,6 +473,10 @@ export class EndpointConfig extends cdk.Resource implements IEndpointConfig {
    * Render the list of instance production variants.
    */
   private renderInstanceProductionVariants(): CfnEndpointConfig.ProductionVariantProperty[] {
+    if (this._instanceProductionVariants.length === 0) {
+      throw new Error('renderInstanceProductionVariants called but no instance variants are configured');
+    }
+    
     return this._instanceProductionVariants.map( v => ({
       acceleratorType: v.acceleratorType?.toString(),
       initialInstanceCount: v.initialInstanceCount,
@@ -489,7 +492,7 @@ export class EndpointConfig extends cdk.Resource implements IEndpointConfig {
    */
   private renderServerlessProductionVariant(): CfnEndpointConfig.ProductionVariantProperty[] {
     if (!this.serverlessProductionVariant) {
-      return [];
+      throw new Error('renderServerlessProductionVariant called but no serverless variant is configured');
     }
 
     const variant = this.serverlessProductionVariant;

packages/@aws-cdk/aws-sagemaker-alpha/test/integ.endpoint-config.js.snapshot/aws-cdk-sagemaker-endpointconfig.assets.json

@@ -739,6 +739,49 @@
      }
     ]
    }
+  },
+  "MinimalServerlessEndpointConfig68CC9C3F": {
+   "Type": "AWS::SageMaker::EndpointConfig",
+   "Properties": {
+    "ProductionVariants": [
+     {
+      "InitialVariantWeight": 1,
+      "ModelName": {
+       "Fn::GetAtt": [
+        "ModelWithoutArtifactAndVpcModel9A8AD144",
+        "ModelName"
+       ]
+      },
+      "ServerlessConfig": {
+       "MaxConcurrency": 1,
+       "MemorySizeInMB": 1024
+      },
+      "VariantName": "minimalServerlessVariant"
+     }
+    ]
+   }
+  },
+  "BoundaryServerlessEndpointConfig0B181608": {
+   "Type": "AWS::SageMaker::EndpointConfig",
+   "Properties": {
+    "ProductionVariants": [
+     {
+      "InitialVariantWeight": 1,
+      "ModelName": {
+       "Fn::GetAtt": [
+        "ModelWithoutArtifactAndVpcModel9A8AD144",
+        "ModelName"
+       ]
+      },
+      "ServerlessConfig": {
+       "MaxConcurrency": 200,
+       "MemorySizeInMB": 6144,
+       "ProvisionedConcurrency": 200
+      },
+      "VariantName": "boundaryServerlessVariant"
+     }
+    ]
+   }
   }
  },
  "Parameters": {

packages/@aws-cdk/aws-sagemaker-alpha/test/integ.endpoint-config.js.snapshot/aws-cdk-sagemaker-endpointconfig.template.json

@@ -1,61 +1,11 @@
 import * as path from 'path';
 import * as ec2 from 'aws-cdk-lib/aws-ec2';
 import * as cdk from 'aws-cdk-lib';
-import { IntegTest } from '@aws-cdk/integ-tests-alpha';
+import { IntegTest, ExpectedResult } from '@aws-cdk/integ-tests-alpha';
 import * as sagemaker from '../lib';
 
 /*
- * Stack verification steps:
- * aws sagemaker describe-endpoint-config --endpoint-config-name <endpoint config name>
- *
- * For instance-based endpoint config, the above command will result in the following output:
- *   {
- *     "EndpointConfigName": "EndpointConfig...",
- *     "EndpointConfigArn": "arn:aws:sagemaker:...",
- *     "ProductionVariants": [
- *         {
- *             "VariantName": "firstVariant",
- *             "ModelName": "ModelWithArtifactAndVpcModel...",
- *             "InitialInstanceCount": 1,
- *             "InstanceType": "ml.m5.large",
- *             "InitialVariantWeight": 1.0
- *         },
- *         {
- *             "VariantName": "secondVariant",
- *             "ModelName": "ModelWithArtifactAndVpcModel...",
- *             "InitialInstanceCount": 1,
- *             "InstanceType": "ml.t2.medium",
- *             "InitialVariantWeight": 1.0
- *         },
- *         {
- *             "VariantName": "thirdVariant",
- *             "ModelName": "ModelWithoutArtifactAndVpcModel...",
- *             "InitialInstanceCount": 1,
- *             "InstanceType": "ml.t2.medium",
- *             "InitialVariantWeight": 2.0
- *         }
- *     ],
- *     "CreationTime": "..."
- *   }
- *
- * For serverless endpoint config, the command will show:
- *   {
- *     "EndpointConfigName": "ServerlessEndpointConfig...",
- *     "EndpointConfigArn": "arn:aws:sagemaker:...",
- *     "ProductionVariants": [
- *         {
- *             "VariantName": "serverlessVariant",
- *             "ModelName": "ModelWithoutArtifactAndVpcModel...",
- *             "InitialVariantWeight": 1.0,
- *             "ServerlessConfig": {
- *                 "MaxConcurrency": 10,
- *                 "MemorySizeInMB": 2048,
- *                 "ProvisionedConcurrency": 5
- *             }
- *         }
- *     ],
- *     "CreationTime": "..."
- *   }
+ * Stack verification is performed using API assertions below.
  */
 
 const app = new cdk.App();
@@ -92,7 +42,7 @@ endpointConfig.addInstanceProductionVariant({
 });
 
 // Test serverless endpoint configuration with all properties
-new sagemaker.EndpointConfig(stack, 'ServerlessEndpointConfig', {
+const serverlessEndpointConfig = new sagemaker.EndpointConfig(stack, 'ServerlessEndpointConfig', {
   serverlessProductionVariant: {
     model: modelWithoutArtifactAndVpc,
     variantName: 'serverlessVariant',
@@ -104,7 +54,7 @@ new sagemaker.EndpointConfig(stack, 'ServerlessEndpointConfig', {
 });
 
 // Test serverless endpoint configuration with minimal properties
-new sagemaker.EndpointConfig(stack, 'MinimalServerlessEndpointConfig', {
+const minimalServerlessEndpointConfig = new sagemaker.EndpointConfig(stack, 'MinimalServerlessEndpointConfig', {
   serverlessProductionVariant: {
     model: modelWithoutArtifactAndVpc,
     variantName: 'minimalServerlessVariant',
@@ -115,7 +65,7 @@ new sagemaker.EndpointConfig(stack, 'MinimalServerlessEndpointConfig', {
 });
 
 // Test serverless endpoint configuration with boundary values
-new sagemaker.EndpointConfig(stack, 'BoundaryServerlessEndpointConfig', {
+const boundaryServerlessEndpointConfig = new sagemaker.EndpointConfig(stack, 'BoundaryServerlessEndpointConfig', {
   serverlessProductionVariant: {
     model: modelWithoutArtifactAndVpc,
     variantName: 'boundaryServerlessVariant',
@@ -125,6 +75,58 @@ new sagemaker.EndpointConfig(stack, 'BoundaryServerlessEndpointConfig', {
   },
 });
 
-new IntegTest(app, 'integtest-endpointconfig', {
+const integ = new IntegTest(app, 'integtest-endpointconfig', {
   testCases: [stack],
 });
+
+// Verify instance-based endpoint config
+integ.assertions.awsApiCall('SageMaker', 'describeEndpointConfig', {
+  EndpointConfigName: endpointConfig.endpointConfigName,
+}).expect(ExpectedResult.objectLike({
+  ProductionVariants: [
+    { VariantName: 'firstVariant', InstanceType: 'ml.m5.large' },
+    { VariantName: 'secondVariant' },
+    { VariantName: 'thirdVariant' },
+  ],
+}));
+
+// Verify serverless endpoint config with all properties
+integ.assertions.awsApiCall('SageMaker', 'describeEndpointConfig', {
+  EndpointConfigName: serverlessEndpointConfig.endpointConfigName,
+}).expect(ExpectedResult.objectLike({
+  ProductionVariants: [{
+    VariantName: 'serverlessVariant',
+    ServerlessConfig: {
+      MaxConcurrency: 10,
+      MemorySizeInMB: 2048,
+      ProvisionedConcurrency: 5,
+    },
+  }],
+}));
+
+// Verify minimal serverless endpoint config
+integ.assertions.awsApiCall('SageMaker', 'describeEndpointConfig', {
+  EndpointConfigName: minimalServerlessEndpointConfig.endpointConfigName,
+}).expect(ExpectedResult.objectLike({
+  ProductionVariants: [{
+    VariantName: 'minimalServerlessVariant',
+    ServerlessConfig: {
+      MaxConcurrency: 1,
+      MemorySizeInMB: 1024,
+    },
+  }],
+}));
+
+// Verify boundary serverless endpoint config
+integ.assertions.awsApiCall('SageMaker', 'describeEndpointConfig', {
+  EndpointConfigName: boundaryServerlessEndpointConfig.endpointConfigName,
+}).expect(ExpectedResult.objectLike({
+  ProductionVariants: [{
+    VariantName: 'boundaryServerlessVariant',
+    ServerlessConfig: {
+      MaxConcurrency: 200,
+      MemorySizeInMB: 6144,
+      ProvisionedConcurrency: 200,
+    },
+  }],
+}));