feat: implement CdkHandler for runtime version enforcement of Lambda handlers

packages/aws-cdk-lib/aws-lambda/lib/runtime.ts

@@ -30,6 +30,12 @@ export interface LambdaRuntimeProps {
    * @default false
    */
   readonly supportsSnapStart?: boolean;
+
+  /**
+   * Whether this runtime is deprecated.
+   * @default false
+   */
+  readonly isDeprecated?: boolean;
 }
 
 export enum RuntimeFamily {
@@ -324,11 +330,17 @@ export class Runtime {
    */
   public readonly isVariable: boolean;
 
+  /**
+   *
+   */
+  public readonly isDeprecated: boolean;
+
   constructor(name: string, family?: RuntimeFamily, props: LambdaRuntimeProps = {}) {
     this.name = name;
     this.supportsInlineCode = !!props.supportsInlineCode;
     this.family = family;
     this.isVariable = !!props.isVariable;
+    this.isDeprecated = props.isDeprecated ?? false;
 
     const imageName = props.bundlingDockerImage ?? `public.ecr.aws/sam/build-${name}`;
     this.bundlingDockerImage = DockerImage.fromRegistry(imageName);

packages/aws-cdk-lib/custom-resources/lib/handler-framework/cdk-function.ts

@@ -0,0 +1,56 @@
+import * as semver from 'semver';
+import { Construct } from 'constructs';
+import { Function, FunctionOptions, Runtime } from '../../../aws-lambda';
+import { CdkHandler } from './cdk-handler';
+import { Lazy } from '../../../core';
+
+/**
+ *
+ */
+export interface CdkFunctionProps extends FunctionOptions {
+  /**
+   *
+   */
+  readonly cdkHandler: CdkHandler,
+}
+
+export class CdkFunction extends Function {
+  private static readonly DEFAULT_RUNTIME = Runtime.NODEJS_LATEST;
+
+  public constructor(scope: Construct, id: string, props: CdkFunctionProps) {
+    super(scope, id, {
+      runtime: Lazy.any(
+        { produce: () => this.determineRuntime(props.cdkHandler.compatibleRuntimes) },
+      ) as unknown as Runtime,
+      code: props.cdkHandler.code,
+      handler: props.cdkHandler.handler,
+      ...props,
+    });
+  }
+
+  private determineRuntime(compatibleRuntimes: Runtime[]) {
+    const compatibleRuntimesLength = compatibleRuntimes.length;
+    if (compatibleRuntimesLength < 1) {
+      throw new Error('`cdkHandler` must specify at least 1 compatible runtime');
+    }
+
+    if (compatibleRuntimes.some(runtime => runtime.runtimeEquals(CdkFunction.DEFAULT_RUNTIME))) {
+      return CdkFunction.DEFAULT_RUNTIME;
+    }
+
+    const sliceStart = 'nodejs'.length;
+    let latestRuntime = compatibleRuntimes[0];
+    for (let idx = 1; idx < compatibleRuntimesLength; idx++) {
+      const runtime = compatibleRuntimes[idx];
+      if (semver.gte(runtime.name.slice(sliceStart), latestRuntime.name.slice(sliceStart))) {
+        latestRuntime = runtime;
+      }
+    }
+
+    if (latestRuntime.isDeprecated) {
+      throw new Error('Latest compatible runtime is deprecated');
+    }
+
+    return latestRuntime;
+  }
+}

packages/aws-cdk-lib/custom-resources/lib/handler-framework/cdk-handler.ts

@@ -0,0 +1,46 @@
+import { Code, Runtime } from '../../../aws-lambda';
+
+/**
+ *
+ */
+export interface CdkHandlerProps {
+  /**
+   *
+   */
+  readonly compatibleRuntimes: Runtime[];
+
+  /**
+   *
+   */
+  readonly handler: string;
+}
+
+export class CdkHandler {
+  /**
+   *
+   */
+  public static fromAsset(path: string, props: CdkHandlerProps) {
+    return new CdkHandler(path, props);
+  }
+
+  /**
+   *
+   */
+  public readonly code: Code;
+
+  /**
+   *
+   */
+  public readonly handler: string;
+
+  /**
+   *
+   */
+  public readonly compatibleRuntimes: Runtime[];
+
+  private constructor(path: string, props: CdkHandlerProps) {
+    this.code = Code.fromAsset(path);
+    this.handler = props.handler;
+    this.compatibleRuntimes = props.compatibleRuntimes;
+  }
+}