chore(lambda): allow the architecture property to be readable from th…

…e Function (aws#17121)

We currently have layers that are designed specifically for arm64 and x86 based functions, and a single stack may have multiple functions with varying architectures. Applying the correct layer to a large list of functions can be a tedious process that may result in applying the incorrect layer to a function. Exposing the architecture at the Function level would allow a user to easily apply the correct layer automatically during deploy by checking the value and pulling the appropriate layer for that architecture. This would eliminate or greatly reduce the possibility of applying the wrong layer type.

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*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-lambda/lib/function.ts

@@ -573,8 +573,13 @@ export class Function extends FunctionBase {
    */
   public readonly deadLetterQueue?: sqs.IQueue;
 
+  /**
+   * The architecture of this Lambda Function (this is an optional attribute and defaults to X86_64).
+   */
+  public readonly architecture?: Architecture;
   public readonly permissionsNode = this.node;
 
+
   protected readonly canCreatePermissions = true;
 
   private readonly layers: ILayerVersion[] = [];
@@ -721,6 +726,8 @@ export class Function extends FunctionBase {
 
     this.runtime = props.runtime;
 
+    this.architecture = props.architecture;
+
     if (props.layers) {
       if (props.runtime === Runtime.FROM_IMAGE) {
         throw new Error('Layers are not supported for container image functions');

packages/@aws-cdk/aws-lambda/test/function.test.ts

@@ -2226,7 +2226,16 @@ describe('function', () => {
       architectures: [lambda.Architecture.X86_64, lambda.Architecture.ARM_64],
     })).toThrow(/one architecture must be specified/);
   });
-
+  test('Architecture is properly readable from the function', () => {
+    const stack = new cdk.Stack();
+    const fn = new lambda.Function(stack, 'MyFunction', {
+      code: lambda.Code.fromInline('foo'),
+      runtime: lambda.Runtime.NODEJS_14_X,
+      handler: 'index.handler',
+      architecture: lambda.Architecture.ARM_64,
+    });
+    expect(fn.architecture?.name).toEqual('arm64');
+  });
 });
 
 function newTestLambda(scope: constructs.Construct) {