feat(lambda): introduce a new kind of Code, CodePipelineCode.

packages/@aws-cdk/aws-lambda/README.md

@@ -72,7 +72,7 @@ fn.addEventSource(new S3EventSource(bucket, {
 
 See the documentation for the __@aws-cdk/aws-lambda-event-sources__ module for more details.
 
-### Lambda in CodePipeline
+### Lambda invoked in CodePipeline
 
 This module also contains an Action that allows you to invoke a Lambda function from CodePipeline:
 
@@ -120,6 +120,68 @@ lambdaAction.outputArtifact('Out2'); // returns the named output Artifact, or th
 See [the AWS documentation](https://docs.aws.amazon.com/codepipeline/latest/userguide/actions-invoke-lambda-function.html)
 on how to write a Lambda function invoked from CodePipeline.
 
+### Lambda deployed through CodePipeline
+
+If you want to deploy your Lambda through CodePipeline,
+you can use the special `Code` convenience method, `lambda.Code.codePipeline`.
+Note that your Lambda must be in a separate Stack than your Pipeline.
+The Lambda itself will be deployed, alongside the entire Stack it belongs to,
+using a CloudFormation CodePipeline Action. Example:
+
+```typescript
+const lambdaCode = lambda.Code.codePipeline(); 
+const lambda = new lambda.Function(lambdaStack, 'Lambda', {
+  code: lambdaCode,
+  handler: 'index.handler',
+  runtime: lambda.Runtime.NodeJS810,
+});
+
+// other resources that your Lambda needs, added to the lambdaStack...
+
+const pipeline = new codepipeline.Pipeline(pipelineStack, 'Pipeline');
+
+// add the source code repository containing this code to your Pipeline,
+// and the source code of the Lambda Function, if they're separate
+pipeline.addStage({
+  name: 'Source',
+  actions: [
+    // ...
+  ],
+});
+
+// add a build Action to your Pipeline,
+// that calls `cdk synth` on the lambdaStack,
+// and saves it to some file,
+// and a separate build for your Lambda source code - if needed
+pipeline.addStage({
+  name: 'Build',
+  actions: [
+    lambdaBuildAction,
+    cdkBuildAction,
+  ],
+});
+
+// finally, deploy your Lambda code
+const parameterOverrides: { [name: string]: any } = {};
+parameterOverrides[lambdaCode.bucketNameParam.logicalId] = lambdaBuildAction.outputArtifact.bucketName;
+parameterOverrides[lambdaCode.bucketKeyParam.logicalId] = lambdaBuildAction.outputArtifact.objectKey;
+pipeline.addStage({
+  name: 'Deploy',
+  actions: [
+    new cloudformation.PipelineCreateUpdateStackAction({
+      actionName: 'Lambda_CFN_Deploy',
+      templatePath: cdkBuildAction.outputArtifact.atPath('template.yaml'),
+      stackName: 'YourDeployStackHere',
+      adminPermissions: true,
+      parameterOverrides,
+      additionalInputArtifacts: [
+        lambdaBuildAction,
+      ],
+    }),
+  ],
+});
+```
+
 ### Lambda with DLQ
 
 ```ts

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

@@ -50,6 +50,10 @@ export abstract class Code {
     return new AssetCode(filePath, assets.AssetPackaging.File);
   }
 
+  public static codePipeline(props?: CodePipelineCodeProps): CodePipelineCode {
+    return new CodePipelineCode(props);
+  }
+
   /**
    * Determines whether this Code is inline code or not.
    */
@@ -150,8 +154,8 @@ export class AssetCode extends Code {
       this.packaging = packaging;
     } else {
       this.packaging = fs.lstatSync(path).isDirectory()
-      ? assets.AssetPackaging.ZipDirectory
-      : assets.AssetPackaging.File;
+        ? assets.AssetPackaging.ZipDirectory
+        : assets.AssetPackaging.File;
     }
   }
 
@@ -175,9 +179,65 @@ export class AssetCode extends Code {
       this.asset!.addResourceMetadata(resource, 'Code');
     }
 
-    return  {
+    return {
       s3Bucket: this.asset!.s3BucketName,
       s3Key: this.asset!.s3ObjectKey
     };
   }
 }
+
+export interface CodePipelineCodeProps {
+  bucketNameParam?: cdk.CfnParameter;
+
+  bucketKeyParam?: cdk.CfnParameter;
+}
+
+export class CodePipelineCode extends Code {
+  public readonly isInline = false;
+  private _bucketNameParam?: cdk.CfnParameter;
+  private _bucketKeyParam?: cdk.CfnParameter;
+
+  constructor(props: CodePipelineCodeProps = {}) {
+    super();
+
+    this._bucketNameParam = props.bucketNameParam;
+    this._bucketKeyParam = props.bucketKeyParam;
+  }
+
+  public bind(construct: cdk.Construct) {
+    if (!this._bucketNameParam) {
+      this._bucketNameParam = new cdk.CfnParameter(construct, 'LambdaSourceBucketNameParameter', {
+        type: 'String',
+      });
+    }
+
+    if (!this._bucketKeyParam) {
+      this._bucketKeyParam = new cdk.CfnParameter(construct, 'LambdaSourceBucketKeyParameter', {
+        type: 'String',
+      });
+    }
+  }
+
+  public _toJSON(_?: cdk.CfnResource): CfnFunction.CodeProperty {
+    return {
+      s3Bucket: this.bucketNameParam.stringValue,
+      s3Key: this.bucketKeyParam.stringValue,
+    };
+  }
+
+  public get bucketNameParam(): cdk.CfnParameter {
+    if (this._bucketNameParam) {
+      return this._bucketNameParam;
+    } else {
+      throw new Error('You have to use CodePipelineCode to create a Lambda Function before you can access the bucketNameParam property');
+    }
+  }
+
+  public get bucketKeyParam(): cdk.CfnParameter {
+    if (this._bucketKeyParam) {
+      return this._bucketKeyParam;
+    } else {
+      throw new Error('You have to use CodePipelineCode to create a Lambda Function before you can access the bucketKeyParam property');
+    }
+  }
+}

packages/@aws-cdk/aws-lambda/test/test.code.ts

@@ -1,4 +1,4 @@
-import { expect, haveResource, ResourcePart } from '@aws-cdk/assert';
+import { expect, haveResource, haveResourceLike, ResourcePart } from '@aws-cdk/assert';
 import assets = require('@aws-cdk/assets');
 import cdk = require('@aws-cdk/cdk');
 import cxapi = require('@aws-cdk/cx-api');
@@ -93,7 +93,86 @@ export = {
       }, ResourcePart.CompleteDefinition));
       test.done();
     }
-  }
+  },
+
+  'lambda.Code.codepipeline': {
+    "automatically creates the Bucket and Key parameters when it's used in a Function"(test: Test) {
+      const stack = new cdk.Stack();
+      const code = new lambda.CodePipelineCode();
+      new lambda.Function(stack, 'Function', {
+        code,
+        runtime: lambda.Runtime.NodeJS810,
+        handler: 'index.handler',
+      });
+
+      expect(stack).to(haveResourceLike('AWS::Lambda::Function', {
+        Code: {
+          S3Bucket: {
+            Ref: "FunctionLambdaSourceBucketNameParameter9E9E108F",
+          },
+          S3Key: {
+            Ref: "FunctionLambdaSourceBucketKeyParameter5BBE948B",
+          },
+        },
+      }));
+
+      test.notEqual(code.bucketNameParam, undefined);
+      test.notEqual(code.bucketKeyParam, undefined);
+
+      test.done();
+    },
+
+    'does not allow accessing the Parameter properties before being used in a Function'(test: Test) {
+      const code = new lambda.CodePipelineCode();
+
+      test.throws(() => {
+        test.notEqual(code.bucketNameParam, undefined);
+      }, /Function/);
+
+      test.throws(() => {
+        test.notEqual(code.bucketKeyParam, undefined);
+      }, /Function/);
+
+      test.done();
+    },
+
+    'allows passing custom Parameters when creating it'(test: Test) {
+      const stack = new cdk.Stack();
+      const bucketNameParam = new cdk.CfnParameter(stack, 'BucketNameParam', {
+        type: 'String',
+      });
+      const bucketKeyParam = new cdk.CfnParameter(stack, 'BucketKeyParam', {
+        type: 'String',
+      });
+
+      const code = lambda.Code.codePipeline({
+        bucketNameParam,
+        bucketKeyParam,
+      });
+
+      new lambda.Function(stack, 'Function', {
+        code,
+        runtime: lambda.Runtime.NodeJS810,
+        handler: 'index.handler',
+      });
+
+      expect(stack).to(haveResourceLike('AWS::Lambda::Function', {
+        Code: {
+          S3Bucket: {
+            Ref: "BucketNameParam",
+          },
+          S3Key: {
+            Ref: "BucketKeyParam",
+          },
+        },
+      }));
+
+      test.notEqual(code.bucketNameParam, undefined);
+      test.notEqual(code.bucketKeyParam, undefined);
+
+      test.done();
+    },
+  },
 };
 
 function defineFunction(code: lambda.Code, runtime: lambda.Runtime = lambda.Runtime.NodeJS810) {