feat(lambda): add support for ephemeral storage (#19552)

Depends on cfnspec bump PR #19553

CFN Docs: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-properties-lambda-function-ephemeralstorage.html

Blog: https://aws.amazon.com/blogs/aws/aws-lambda-now-supports-up-to-10-gb-ephemeral-storage/

<img width="1453" alt="image" src="https://user-images.githubusercontent.com/31543/160157013-1cc67553-60e7-461e-b90b-1e47d0d1215b.png">


Closes #19605.

----

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### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/master/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/master/INTEGRATION_TESTS.md)?
	* [ ] Did you use `cdk-integ` to deploy the infrastructure and generate the snapshot (i.e. `cdk-integ` without `--dry-run`)?

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

Author: robertd

Diff for: packages/@aws-cdk/aws-lambda/README.md

@@ -710,6 +710,24 @@ const fn = new lambda.Function(this, 'MyLambda', {
 });
 ```
 
+## Ephemeral Storage
+
+You can configure ephemeral storage on a function to control the amount of storage it gets for reading
+or writing data, allowing you to use AWS Lambda for ETL jobs, ML inference, or other data-intensive workloads.
+The ephemeral storage will be accessible in the functions' `/tmp` directory.
+
+```ts
+import { Size } from '@aws-cdk/core';
+
+const fn = new lambda.Function(this, 'MyFunction', {
+  runtime: lambda.Runtime.NODEJS_14_X,
+  handler: 'index.handler',
+  code: lambda.Code.fromAsset(path.join(__dirname, 'lambda-handler')),
+  ephemeralStorageSize: Size.mebibytes(1024),
+});
+```
+
+Read more about using this feature in [this AWS blog post](https://aws.amazon.com/blogs/aws/aws-lambda-now-supports-up-to-10-gb-ephemeral-storage/).
 
 ## Singleton Function
 

Diff for: packages/@aws-cdk/aws-lambda/lib/function.ts

@@ -6,7 +6,7 @@ import * as kms from '@aws-cdk/aws-kms';
 import * as logs from '@aws-cdk/aws-logs';
 import * as sns from '@aws-cdk/aws-sns';
 import * as sqs from '@aws-cdk/aws-sqs';
-import { Annotations, ArnFormat, CfnResource, Duration, Fn, Lazy, Names, Stack, Token } from '@aws-cdk/core';
+import { Annotations, ArnFormat, CfnResource, Duration, Fn, Lazy, Names, Size, Stack, Token } from '@aws-cdk/core';
 import { Construct } from 'constructs';
 import { Architecture } from './architecture';
 import { Code, CodeConfig } from './code';
@@ -95,6 +95,13 @@ export interface FunctionOptions extends EventInvokeConfigOptions {
    */
   readonly memorySize?: number;
 
+  /**
+   * The size of the function’s /tmp directory in MB.
+   *
+   * @default 512 MiB
+   */
+  readonly ephemeralStorageSize?: Size;
+
   /**
    * Initial policy statements to add to the created Lambda Role.
    *
@@ -747,6 +754,11 @@ export class Function extends FunctionBase {
     }
     this._architecture = props.architecture ?? (props.architectures && props.architectures[0]);
 
+    if (props.ephemeralStorageSize && !props.ephemeralStorageSize.isUnresolved()
+      && (props.ephemeralStorageSize.toMebibytes() < 512 || props.ephemeralStorageSize.toMebibytes() > 10240)) {
+      throw new Error(`Ephemeral storage size must be between 512 and 10240 MB, received ${props.ephemeralStorageSize}.`);
+    }
+
     const resource: CfnFunction = new CfnFunction(this, 'Resource', {
       functionName: this.physicalName,
       description: props.description,
@@ -767,6 +779,9 @@ export class Function extends FunctionBase {
       // Token, actually *modifies* the 'environment' map.
       environment: Lazy.uncachedAny({ produce: () => this.renderEnvironment() }),
       memorySize: props.memorySize,
+      ephemeralStorage: props.ephemeralStorageSize ? {
+        size: props.ephemeralStorageSize.toMebibytes(),
+      } : undefined,
       vpcConfig: this.configureVpc(props),
       deadLetterConfig: this.buildDeadLetterConfig(dlqTopicOrQueue),
       tracingConfig: this.buildTracingConfig(props),

Diff for: packages/@aws-cdk/aws-lambda/test/function.test.ts

@@ -15,6 +15,7 @@ import * as cdk from '@aws-cdk/core';
 import * as constructs from 'constructs';
 import * as _ from 'lodash';
 import * as lambda from '../lib';
+import { Lazy, Size } from '@aws-cdk/core';
 
 describe('function', () => {
   test('default function', () => {
@@ -2584,6 +2585,7 @@ 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', {
@@ -2635,6 +2637,50 @@ describe('function', () => {
   });
 });
 
+test('throws if ephemeral storage size is out of bound', () => {
+  const stack = new cdk.Stack();
+  expect(() => new lambda.Function(stack, 'MyLambda', {
+    code: new lambda.InlineCode('foo'),
+    handler: 'bar',
+    runtime: lambda.Runtime.NODEJS_14_X,
+    ephemeralStorageSize: Size.mebibytes(511),
+  })).toThrow(/Ephemeral storage size must be between 512 and 10240 MB/);
+});
+
+test('set ephemeral storage to desired size', () => {
+  const stack = new cdk.Stack();
+  new lambda.Function(stack, 'MyLambda', {
+    code: new lambda.InlineCode('foo'),
+    handler: 'bar',
+    runtime: lambda.Runtime.NODEJS_14_X,
+    ephemeralStorageSize: Size.mebibytes(1024),
+  });
+
+  Template.fromStack(stack).hasResource('AWS::Lambda::Function', {
+    Properties:
+    {
+      Code: { ZipFile: 'foo' },
+      Handler: 'bar',
+      Runtime: 'nodejs14.x',
+      EphemeralStorage: {
+        Size: 1024,
+      },
+    },
+  });
+});
+
+test('ephemeral storage allows unresolved tokens', () => {
+  const stack = new cdk.Stack();
+  expect(() => {
+    new lambda.Function(stack, 'MyLambda', {
+      code: new lambda.InlineCode('foo'),
+      handler: 'bar',
+      runtime: lambda.Runtime.NODEJS_14_X,
+      ephemeralStorageSize: Size.mebibytes(Lazy.number({ produce: () => 1024 })),
+    });
+  }).not.toThrow();
+});
+
 function newTestLambda(scope: constructs.Construct) {
   return new lambda.Function(scope, 'MyLambda', {
     code: new lambda.InlineCode('foo'),