feat(lambda-python): bundle dependencies in a lambda layer

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

@@ -16,6 +16,11 @@ export interface BundlingOptions {
    * The runtime of the lambda function
    */
   readonly runtime: lambda.Runtime;
+
+  /**
+   * Install dependencies while bundling
+   */
+  readonly installDependencies: boolean;
 }
 
 /**
@@ -25,9 +30,10 @@ export function bundle(options: BundlingOptions): lambda.AssetCode {
   let installer = options.runtime === lambda.Runtime.PYTHON_2_7 ? Installer.PIP : Installer.PIP3;
 
   let hasRequirements = fs.existsSync(path.join(options.entry, 'requirements.txt'));
+  let installDependencies = options.installDependencies;
 
   let depsCommand = chain([
-    hasRequirements ? `${installer} install -r requirements.txt -t ${cdk.AssetStaging.BUNDLING_OUTPUT_DIR}` : '',
+    hasRequirements && installDependencies ? `${installer} install -r requirements.txt -t ${cdk.AssetStaging.BUNDLING_OUTPUT_DIR}` : '',
     `cp -au . ${cdk.AssetStaging.BUNDLING_OUTPUT_DIR}`,
   ]);
 
@@ -47,3 +53,29 @@ enum Installer {
 function chain(commands: string[]): string {
   return commands.filter(c => !!c).join(' && ');
 }
+
+export interface DependencyBundlingOptions {
+  /**
+   * Entry path
+   */
+  readonly entry: string;
+
+  /**
+   * The runtime of the lambda function
+   */
+  readonly runtime: lambda.Runtime;
+}
+export function bundleDependencies(options: DependencyBundlingOptions): lambda.AssetCode {
+  let installer = options.runtime === lambda.Runtime.PYTHON_2_7 ? Installer.PIP : Installer.PIP3;
+  let depsCommand = chain([
+    `${installer} install -r requirements.txt -t ${cdk.AssetStaging.BUNDLING_OUTPUT_DIR}/python`,
+  ]);
+
+  return lambda.Code.fromAsset(options.entry, {
+    bundling: {
+      image: options.runtime.bundlingDockerImage,
+      command: ['bash', '-c', depsCommand],
+    },
+    exclude: ['*', '!requirements.txt'],
+  });
+}

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

@@ -2,7 +2,7 @@ import * as fs from 'fs';
 import * as path from 'path';
 import * as lambda from '@aws-cdk/aws-lambda';
 import * as cdk from '@aws-cdk/core';
-import { bundle } from './bundling';
+import { bundle, bundleDependencies } from './bundling';
 
 /**
  * Properties for a PythonFunction
@@ -34,6 +34,18 @@ export interface PythonFunctionProps extends lambda.FunctionOptions {
    * @default lambda.Runtime.PYTHON_3_7
    */
   readonly runtime?: lambda.Runtime;
+
+  /**
+   * Install dependencies
+   * @default true
+   */
+  readonly installDependencies?: boolean;
+
+  /**
+   * Use a dependency lambda layer for packages.
+   * @default false
+   */
+  readonly useDependencyLayer?: boolean;
 }
 
 /**
@@ -59,6 +71,8 @@ export class PythonFunction extends lambda.Function {
 
     const handler = props.handler ?? 'handler';
     const runtime = props.runtime ?? lambda.Runtime.PYTHON_3_7;
+    const useDependencyLayer = props.useDependencyLayer ?? false;
+    const installDependencies = props.installDependencies ?? true;
 
     super(scope, id, {
       ...props,
@@ -67,8 +81,19 @@ export class PythonFunction extends lambda.Function {
         ...props,
         entry,
         runtime,
+        installDependencies: !useDependencyLayer && installDependencies,
       }),
       handler: `${index.slice(0, -3)}.${handler}`,
     });
+
+    if (installDependencies && useDependencyLayer && fs.existsSync(path.join(entry, 'requirements.txt'))) {
+      this.addLayers(new lambda.LayerVersion(this, 'Dependencies', {
+        compatibleRuntimes: [runtime],
+        code: bundleDependencies({
+          entry,
+          runtime,
+        }),
+      }));
+    }
   }
 }

packages/@aws-cdk/aws-lambda-python/test/bundling.test.ts

@@ -1,6 +1,6 @@
 import * as fs from 'fs';
 import { Code, Runtime } from '@aws-cdk/aws-lambda';
-import { bundle } from '../lib/bundling';
+import { bundle, bundleDependencies } from '../lib/bundling';
 
 jest.mock('@aws-cdk/aws-lambda');
 const existsSyncOriginal = fs.existsSync;
@@ -14,6 +14,7 @@ test('Bundling', () => {
   bundle({
     entry: '/project/folder',
     runtime: Runtime.PYTHON_3_7,
+    installDependencies: true,
   });
 
   // Correctly bundles
@@ -41,6 +42,7 @@ test('Bundling with requirements.txt installed', () => {
   bundle({
     entry: '/project/folder',
     runtime: Runtime.PYTHON_3_7,
+    installDependencies: true,
   });
 
   // Correctly bundles with requirements.txt pip installed
@@ -65,6 +67,7 @@ test('Bundling Python 2.7 with requirements.txt installed', () => {
   bundle({
     entry: '/project/folder',
     runtime: Runtime.PYTHON_2_7,
+    installDependencies: true,
   });
 
   // Correctly bundles with requirements.txt pip installed
@@ -77,3 +80,46 @@ test('Bundling Python 2.7 with requirements.txt installed', () => {
     }),
   });
 });
+
+test('Bundling can dependencies can be switched off', () => {
+  existsSyncMock.mockImplementation((p: fs.PathLike) => {
+    if (/requirements.txt/.test(p.toString())) {
+      return true;
+    }
+    return existsSyncOriginal(p);
+  });
+
+  bundle({
+    entry: '/project/folder',
+    runtime: Runtime.PYTHON_3_7,
+    installDependencies: false,
+  });
+
+  // Does not install dependencies when instructed not to.
+  expect(Code.fromAsset).toHaveBeenCalledWith('/project/folder', {
+    bundling: expect.objectContaining({
+      command: [
+        'bash', '-c',
+        'cp -au . /asset-output',
+      ],
+    }),
+  });
+});
+
+test('Bundling dependencies for a lambda layer', () => {
+
+  bundleDependencies({
+    entry: '/project/folder',
+    runtime: Runtime.PYTHON_3_7,
+  });
+
+  expect(Code.fromAsset).toHaveBeenCalledWith('/project/folder', {
+    bundling: expect.objectContaining({
+      command: [
+        'bash', '-c',
+        'pip3 install -r requirements.txt -t /asset-output/python',
+      ],
+    }),
+    exclude: ['*', '!requirements.txt'],
+  });
+});

packages/@aws-cdk/aws-lambda-python/test/integ.function.dependencies-layer.expected.json

@@ -0,0 +1,173 @@
+{
+  "Resources": {
+    "myhandlerServiceRole77891068": {
+      "Type": "AWS::IAM::Role",
+      "Properties": {
+        "AssumeRolePolicyDocument": {
+          "Statement": [
+            {
+              "Action": "sts:AssumeRole",
+              "Effect": "Allow",
+              "Principal": {
+                "Service": "lambda.amazonaws.com"
+              }
+            }
+          ],
+          "Version": "2012-10-17"
+        },
+        "ManagedPolicyArns": [
+          {
+            "Fn::Join": [
+              "",
+              [
+                "arn:",
+                {
+                  "Ref": "AWS::Partition"
+                },
+                ":iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
+              ]
+            ]
+          }
+        ]
+      }
+    },
+    "myhandlerD202FA8E": {
+      "Type": "AWS::Lambda::Function",
+      "Properties": {
+        "Code": {
+          "S3Bucket": {
+            "Ref": "AssetParameters4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5fS3Bucket2F5C84CD"
+          },
+          "S3Key": {
+            "Fn::Join": [
+              "",
+              [
+                {
+                  "Fn::Select": [
+                    0,
+                    {
+                      "Fn::Split": [
+                        "||",
+                        {
+                          "Ref": "AssetParameters4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5fS3VersionKey83071E5E"
+                        }
+                      ]
+                    }
+                  ]
+                },
+                {
+                  "Fn::Select": [
+                    1,
+                    {
+                      "Fn::Split": [
+                        "||",
+                        {
+                          "Ref": "AssetParameters4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5fS3VersionKey83071E5E"
+                        }
+                      ]
+                    }
+                  ]
+                }
+              ]
+            ]
+          }
+        },
+        "Handler": "index.handler",
+        "Role": {
+          "Fn::GetAtt": [
+            "myhandlerServiceRole77891068",
+            "Arn"
+          ]
+        },
+        "Runtime": "python3.8",
+        "Layers": [
+          {
+            "Ref": "myhandlerDependencies20391420"
+          }
+        ]
+      },
+      "DependsOn": [
+        "myhandlerServiceRole77891068"
+      ]
+    },
+    "myhandlerDependencies20391420": {
+      "Type": "AWS::Lambda::LayerVersion",
+      "Properties": {
+        "Content": {
+          "S3Bucket": {
+            "Ref": "AssetParameters252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29S3Bucket642CA4C7"
+          },
+          "S3Key": {
+            "Fn::Join": [
+              "",
+              [
+                {
+                  "Fn::Select": [
+                    0,
+                    {
+                      "Fn::Split": [
+                        "||",
+                        {
+                          "Ref": "AssetParameters252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29S3VersionKey64C9926E"
+                        }
+                      ]
+                    }
+                  ]
+                },
+                {
+                  "Fn::Select": [
+                    1,
+                    {
+                      "Fn::Split": [
+                        "||",
+                        {
+                          "Ref": "AssetParameters252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29S3VersionKey64C9926E"
+                        }
+                      ]
+                    }
+                  ]
+                }
+              ]
+            ]
+          }
+        },
+        "CompatibleRuntimes": [
+          "python3.8"
+        ]
+      }
+    }
+  },
+  "Parameters": {
+    "AssetParameters4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5fS3Bucket2F5C84CD": {
+      "Type": "String",
+      "Description": "S3 bucket for asset \"4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5f\""
+    },
+    "AssetParameters4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5fS3VersionKey83071E5E": {
+      "Type": "String",
+      "Description": "S3 key for asset version \"4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5f\""
+    },
+    "AssetParameters4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5fArtifactHashA46D9597": {
+      "Type": "String",
+      "Description": "Artifact hash for asset \"4eea0d640af1864916a242dbdb7f389832098cafcef9a336426f3e722767cd5f\""
+    },
+    "AssetParameters252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29S3Bucket642CA4C7": {
+      "Type": "String",
+      "Description": "S3 bucket for asset \"252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29\""
+    },
+    "AssetParameters252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29S3VersionKey64C9926E": {
+      "Type": "String",
+      "Description": "S3 key for asset version \"252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29\""
+    },
+    "AssetParameters252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29ArtifactHash8A3CA2CC": {
+      "Type": "String",
+      "Description": "Artifact hash for asset \"252e7578113dbc054fc4bc9801f3a9da383755d081008bd4d023b030d198cd29\""
+    }
+  },
+  "Outputs": {
+    "FunctionName": {
+      "Value": {
+        "Ref": "myhandlerD202FA8E"
+      }
+    }
+  }
+}

packages/@aws-cdk/aws-lambda-python/test/integ.function.dependencies-layer.ts

@@ -0,0 +1,30 @@
+import * as path from 'path';
+import { Runtime } from '@aws-cdk/aws-lambda';
+import { App, CfnOutput, Construct, Stack, StackProps } from '@aws-cdk/core';
+import * as lambda from '../lib';
+
+/*
+ * Stack verification steps:
+ * cdk deploy --app "node integ.function.dependencies-layer.js"
+ * aws lambda invoke --function-name <function name> --invocation-type Event --payload $(base64 <<<'"OK"') response.json
+ */
+
+class TestStack extends Stack {
+  constructor(scope: Construct, id: string, props?: StackProps) {
+    super(scope, id, props);
+
+    const fn = new lambda.PythonFunction(this, 'my_handler', {
+      entry: path.join(__dirname, 'lambda-handler2'),
+      runtime: Runtime.PYTHON_3_8,
+      useDependencyLayer: true,
+    });
+
+    new CfnOutput(this, 'FunctionName', {
+      value: fn.functionName,
+    });
+  }
+}
+
+const app = new App();
+new TestStack(app, 'cdk-integ-lambda-dependencies-layer');
+app.synth();