feat(lambda-python-alpha): cache python lambda dependencies usig lambda layer

packages/@aws-cdk/aws-lambda-python-alpha/lib/bundling.ts

@@ -47,6 +47,12 @@ export interface BundlingProps extends BundlingOptions {
    * @default - BundlingFileAccess.BIND_MOUNT
    */
   bundlingFileAccess?: BundlingFileAccess;
+
+  /**
+   * Whether or not to install the dependencies
+   * @default true
+   */
+  readonly installDependencies?: boolean;
 }
 
 /**
@@ -73,6 +79,7 @@ export class Bundling implements CdkBundlingOptions {
   public readonly securityOpt?: string;
   public readonly network?: string;
   public readonly bundlingFileAccess?: BundlingFileAccess;
+  public readonly installDependencies?: boolean;
 
   constructor(props: BundlingProps) {
     const {
@@ -85,6 +92,7 @@ export class Bundling implements CdkBundlingOptions {
       poetryWithoutUrls,
       commandHooks,
       assetExcludes = [],
+      installDependencies = true,
     } = props;
 
     const outputPath = path.posix.join(AssetStaging.BUNDLING_OUTPUT_DIR, outputPathSuffix);
@@ -97,6 +105,7 @@ export class Bundling implements CdkBundlingOptions {
       poetryWithoutUrls,
       commandHooks,
       assetExcludes,
+      installDependencies,
     });
 
     this.image = image ?? DockerImage.fromBuild(path.join(__dirname, '..', 'lib'), {
@@ -119,17 +128,19 @@ export class Bundling implements CdkBundlingOptions {
   }
 
   private createBundlingCommand(options: BundlingCommandOptions): string[] {
-    const packaging = Packaging.fromEntry(options.entry, options.poetryIncludeHashes, options.poetryWithoutUrls);
     let bundlingCommands: string[] = [];
     bundlingCommands.push(...options.commandHooks?.beforeBundling(options.inputDir, options.outputDir) ?? []);
     const exclusionStr = options.assetExcludes?.map(item => `--exclude='${item}'`).join(' ');
     bundlingCommands.push([
       'rsync', '-rLv', exclusionStr ?? '', `${options.inputDir}/`, options.outputDir,
     ].filter(item => item).join(' '));
-    bundlingCommands.push(`cd ${options.outputDir}`);
-    bundlingCommands.push(packaging.exportCommand ?? '');
-    if (packaging.dependenciesFile) {
-      bundlingCommands.push(`python -m pip install -r ${DependenciesFile.PIP} -t ${options.outputDir}`);
+    if (options.installDependencies) {
+      const packaging = Packaging.fromEntry(options.entry, options.poetryIncludeHashes, options.poetryWithoutUrls);
+      bundlingCommands.push(`cd ${options.outputDir}`);
+      bundlingCommands.push(packaging.exportCommand ?? '');
+      if (packaging.dependenciesFile) {
+        bundlingCommands.push(`python -m pip install -r ${DependenciesFile.PIP} -t ${options.outputDir}`);
+      }
     }
     bundlingCommands.push(...options.commandHooks?.afterBundling(options.inputDir, options.outputDir) ?? []);
     return bundlingCommands;
@@ -144,6 +155,7 @@ interface BundlingCommandOptions {
   readonly poetryIncludeHashes?: boolean;
   readonly poetryWithoutUrls?: boolean;
   readonly commandHooks?: ICommandHooks;
+  readonly installDependencies: boolean;
 }
 
 /**

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

@@ -1,10 +1,12 @@
 import * as fs from 'fs';
 import * as path from 'path';
-import { Function, FunctionOptions, Runtime, RuntimeFamily } from 'aws-cdk-lib/aws-lambda';
-import { Stack } from 'aws-cdk-lib/core';
+import { Architecture, Function, FunctionOptions, Runtime, RuntimeFamily } from 'aws-cdk-lib/aws-lambda';
+import { AssetHashType, Stack } from 'aws-cdk-lib/core';
 import { Construct } from 'constructs';
 import { Bundling } from './bundling';
 import { BundlingOptions } from './types';
+import { PythonLayerVersion } from './layer';
+import { Packaging } from './packaging';
 
 /**
  * Properties for a PythonFunction
@@ -42,6 +44,12 @@ export interface PythonFunctionProps extends FunctionOptions {
    * @default - Use the default bundling Docker image, with x86_64 architecture.
    */
   readonly bundling?: BundlingOptions;
+
+  /**
+   * Whether or not to create a layer for the function's dependencies.
+   * @default - No layer is created.
+   */
+  readonly layer?: boolean;
 }
 
 /**
@@ -60,13 +68,30 @@ export class PythonFunction extends Function {
     if (!fs.existsSync(resolvedIndex)) {
       throw new Error(`Cannot find index file at ${resolvedIndex}`);
     }
-
+    
     const resolvedHandler =`${index.slice(0, -3)}.${handler}`.replace(/\//g, '.');
 
     if (props.runtime && props.runtime.family !== RuntimeFamily.PYTHON) {
       throw new Error('Only `PYTHON` runtimes are supported.');
     }
 
+    // Layer
+    let layer: PythonLayerVersion | undefined;
+    if (props.layer) {
+      layer = new PythonLayerVersion(scope, `${id}Layer`, {
+        entry,
+        compatibleRuntimes: [props.runtime],
+        compatibleArchitectures: [props.architecture ?? Architecture.X86_64],
+        bundling: {
+          ...props.bundling,
+          installDependencies: true,
+          // assetExcludes: ["TODO: exclude everything except the dependencies file"]
+          assetHashType: AssetHashType.CUSTOM,
+          assetHash: Packaging.dependenciesHash(entry),
+        },
+      });
+    }
+
     super(scope, id, {
       ...props,
       runtime,
@@ -77,8 +102,13 @@ export class PythonFunction extends Function {
         // define architecture based on the target architecture of the function, possibly overriden in bundling options
         architecture: props.architecture,
         ...props.bundling,
+        installDependencies: layer ? false : true,
       }),
       handler: resolvedHandler,
+      layers: layer ? [
+        ...(props.layers ?? []),
+        layer,
+      ] : props.layers,
     });
   }
 }

packages/@aws-cdk/aws-lambda-python-alpha/lib/packaging.ts

@@ -1,5 +1,6 @@
 import * as fs from 'fs';
 import * as path from 'path';
+import * as crypto from 'crypto';
 
 export enum DependenciesFile {
   PIP = 'requirements.txt',
@@ -99,6 +100,47 @@ export class Packaging {
     }
   }
 
+  public static getAssetHash(entry: string): string | undefined {
+    const hash = crypto.createHash('sha256');
+    if (fs.existsSync(path.join(entry, DependenciesFile.PIPENV))) {
+      const dependenciesFile = fs.readFileSync(path.join(entry, DependenciesFile.PIPENV));
+      hash.update(dependenciesFile);
+      return hash.digest('hex');
+    } if (fs.existsSync(path.join(entry, DependenciesFile.POETRY))) {
+      const dependenciesFile = fs.readFileSync(path.join(entry, DependenciesFile.POETRY));
+      hash.update(dependenciesFile);
+      return hash.digest('hex');
+    } else if (fs.existsSync(path.join(entry, DependenciesFile.PIP))) {
+      const dependenciesFile = fs.readFileSync(path.join(entry, DependenciesFile.PIP));
+      hash.update(dependenciesFile);
+      return hash.digest('hex');
+    } else {
+      throw new Error('No dependencies file found');
+    }
+  }
+
+  /**
+   * Compute the asset hash of the dependencies file.
+   */
+  public static dependenciesHash(entry: string): string | undefined {
+    const hash = crypto.createHash('sha256');
+    if (fs.existsSync(path.join(entry, DependenciesFile.PIPENV))) {
+      const dependenciesFile = fs.readFileSync(path.join(entry, DependenciesFile.PIPENV));
+      hash.update(dependenciesFile);
+      return hash.digest('hex');
+    } if (fs.existsSync(path.join(entry, DependenciesFile.POETRY))) {
+      const dependenciesFile = fs.readFileSync(path.join(entry, DependenciesFile.POETRY));
+      hash.update(dependenciesFile);
+      return hash.digest('hex');
+    } else if (fs.existsSync(path.join(entry, DependenciesFile.PIP))) {
+      const dependenciesFile = fs.readFileSync(path.join(entry, DependenciesFile.PIP));
+      hash.update(dependenciesFile);
+      return hash.digest('hex');
+    } else {
+      return
+    }
+  }
+
   public readonly dependenciesFile: string;
   public readonly exportCommand?: string;
   constructor(props: PackagingProps) {

packages/@aws-cdk/aws-lambda-python-alpha/lib/types.ts

@@ -105,6 +105,12 @@ export interface BundlingOptions extends DockerRunOptions {
    * @default - BundlingFileAccess.BIND_MOUNT
    */
   readonly bundlingFileAccess?: BundlingFileAccess;
+
+  /**
+   * Whether or not to install the dependencies
+   * @default true
+   */
+  readonly installDependencies?: boolean;
 }
 
 /**