feat(lambda): add support for ephemeral storage

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

@@ -95,6 +95,13 @@ export interface FunctionOptions extends EventInvokeConfigOptions {
    */
   readonly memorySize?: number;
 
+  /**
+   * The size of the function’s /tmp directory.
+   *
+   * @default 512
+   */
+  readonly ephemeralStorageSize?: number;
+
   /**
    * Initial policy statements to add to the created Lambda Role.
    *
@@ -763,6 +770,7 @@ export class Function extends FunctionBase {
       // Token, actually *modifies* the 'environment' map.
       environment: Lazy.uncachedAny({ produce: () => this.renderEnvironment() }),
       memorySize: props.memorySize,
+      ephemeralStorage: this.buildEphemeralStorage(props),
       vpcConfig: this.configureVpc(props),
       deadLetterConfig: this.buildDeadLetterConfig(dlqTopicOrQueue),
       tracingConfig: this.buildTracingConfig(props),
@@ -1128,6 +1136,16 @@ Environment variables can be marked for removal when used in Lambda@Edge by sett
     }
   }
 
+  private buildEphemeralStorage(props: FunctionProps) {
+    if (props.ephemeralStorageSize === undefined) {
+      return undefined;
+    }
+
+    return {
+      size: props.ephemeralStorageSize,
+    }
+  }
+
   private buildTracingConfig(props: FunctionProps) {
     if (props.tracing === undefined || props.tracing === Tracing.DISABLED) {
       return undefined;