feat(events-targets): LambdaFunction (#2350)

The `LambdaFunction` class can be used to bind an AWS Lambda function as an event
rule target.

Related #1663 

BREAKING CHANGE: `lambda.Function` no longer implements `IEventRuleTarget`. Instead, use
`@aws-cdk/aws-events-targets.LambdaFunction`.

packages/@aws-cdk/aws-events-targets/lib/index.ts

@@ -1,2 +1,3 @@
 export * from './sns';
-export * from './codebuild';
+export * from './codebuild';
+export * from './lambda';

packages/@aws-cdk/aws-events-targets/lib/lambda.ts

@@ -0,0 +1,36 @@
+import events = require('@aws-cdk/aws-events');
+import iam = require('@aws-cdk/aws-iam');
+import lambda = require('@aws-cdk/aws-lambda');
+
+/**
+ * Use an AWS Lambda function as an event rule target.
+ */
+export class LambdaFunction implements events.IEventRuleTarget {
+
+ /**
+ * @param handler The lambda function
+ */
+ constructor(private readonly handler: lambda.IFunction) {
+
+ }
+
+ /**
+ * Returns a RuleTarget that can be used to trigger this Lambda as a
+ * result from a CloudWatch event.
+ */
+ public asEventRuleTarget(ruleArn: string, ruleId: string): events.EventRuleTargetProps {
+ const permissionId = `AllowEventRule${ruleId}`;
+ if (!this.handler.node.tryFindChild(permissionId)) {
+ this.handler.addPermission(permissionId, {
+ action: 'lambda:InvokeFunction',
+ principal: new iam.ServicePrincipal('events.amazonaws.com'),
+ sourceArn: ruleArn
+ });
+ }
+
+ return {
+ id: this.handler.node.id,
+ arn: this.handler.functionArn,
+ };
+ }
+}

packages/@aws-cdk/aws-lambda/test/integ.events.ts → packages/@aws-cdk/aws-events-targets/test/lambda/integ.events.ts

@@ -1,6 +1,7 @@
 import events = require('@aws-cdk/aws-events');
+import lambda = require('@aws-cdk/aws-lambda');
 import cdk = require('@aws-cdk/cdk');
-import lambda = require('../lib');
+import targets = require('../../lib');
 
 const app = new cdk.App();
 
@@ -13,10 +14,10 @@ const fn = new lambda.Function(stack, 'MyFunc', {
 });
 
 const timer = new events.EventRule(stack, 'Timer', { scheduleExpression: 'rate(1 minute)' });
-timer.addTarget(fn);
+timer.addTarget(new targets.LambdaFunction(fn));
 
 const timer2 = new events.EventRule(stack, 'Timer2', { scheduleExpression: 'rate(2 minutes)' });
-timer2.addTarget(fn);
+timer2.addTarget(new targets.LambdaFunction(fn));
 
 app.run();
 

packages/@aws-cdk/aws-events-targets/test/lambda/lambda.test.ts

@@ -0,0 +1,62 @@
+import { countResources, expect, haveResource } from '@aws-cdk/assert';
+import events = require('@aws-cdk/aws-events');
+import lambda = require('@aws-cdk/aws-lambda');
+import cdk = require('@aws-cdk/cdk');
+import targets = require('../../lib');
+
+test('use lambda as an event rule target', () => {
+ // GIVEN
+ const stack = new cdk.Stack();
+ const fn = newTestLambda(stack);
+ const rule1 = new events.EventRule(stack, 'Rule', { scheduleExpression: 'rate(1 minute)' });
+ const rule2 = new events.EventRule(stack, 'Rule2', { scheduleExpression: 'rate(5 minutes)' });
+
+ // WHEN
+ rule1.addTarget(new targets.LambdaFunction(fn));
+ rule2.addTarget(new targets.LambdaFunction(fn));
+
+ // THEN
+ const lambdaId = "MyLambdaCCE802FB";
+
+ expect(stack).to(haveResource('AWS::Lambda::Permission', {
+ Action: "lambda:InvokeFunction",
+ FunctionName: {
+ "Fn::GetAtt": [
+ lambdaId,
+ "Arn"
+ ]
+ },
+ Principal: "events.amazonaws.com",
+ SourceArn: { "Fn::GetAtt": ["Rule4C995B7F", "Arn"] }
+ }));
+
+ expect(stack).to(haveResource('AWS::Lambda::Permission', {
+ Action: "lambda:InvokeFunction",
+ FunctionName: {
+ "Fn::GetAtt": [
+ lambdaId,
+ "Arn"
+ ]
+ },
+ Principal: "events.amazonaws.com",
+ SourceArn: { "Fn::GetAtt": ["Rule270732244", "Arn"] }
+ }));
+
+ expect(stack).to(countResources('AWS::Events::Rule', 2));
+ expect(stack).to(haveResource('AWS::Events::Rule', {
+ Targets: [
+ {
+ Arn: { "Fn::GetAtt": [lambdaId, "Arn"] },
+ Id: "MyLambda"
+ }
+ ]
+ }));
+});
+
+function newTestLambda(scope: cdk.Construct) {
+ return new lambda.Function(scope, 'MyLambda', {
+ code: new lambda.InlineCode('foo'),
+ handler: 'bar',
+ runtime: lambda.Runtime.Python27
+ });
+}

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

@@ -72,4 +72,5 @@ The following targets are supported:
 
 * `targets.SnsTopic`: publish into an SNS topic when an event rule is triggered.
 * `targets.CodeBuildProject`: start a CodeBuild project when an event rule is triggered.
+* `targets.LambdaFunction`: invoke an AWS Lambda function when an event rule is triggered.
 

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

@@ -40,6 +40,16 @@ granting permissions to other AWS accounts or organizations.
 
 [Example of Lambda Layer usage](test/integ.layer-version.lit.ts)
 
+## Event Rule Target
+
+You can use an AWS Lambda function as a target for an Amazon CloudWatch event
+rule:
+
+```ts
+import targets = require('@aws-cdk/aws-events-targets');
+rule.addTarget(new targets.LambdaFunction(myFunction));
+```
+
 ### Event Sources
 
 AWS Lambda supports a [variety of event sources](https://docs.aws.amazon.com/lambda/latest/dg/invoking-lambda-function.html).

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

@@ -1,6 +1,5 @@
 import cloudwatch = require('@aws-cdk/aws-cloudwatch');
 import ec2 = require('@aws-cdk/aws-ec2');
-import events = require('@aws-cdk/aws-events');
 import iam = require('@aws-cdk/aws-iam');
 import logs = require('@aws-cdk/aws-logs');
 import s3n = require('@aws-cdk/aws-s3-notifications');
@@ -11,7 +10,7 @@ import { IEventSource } from './event-source';
 import { CfnPermission } from './lambda.generated';
 import { Permission } from './permission';
 
-export interface IFunction extends IResource, events.IEventRuleTarget, logs.ILogSubscriptionDestination,
+export interface IFunction extends IResource, logs.ILogSubscriptionDestination,
  s3n.IBucketNotificationDestination, ec2.IConnectable, stepfunctions.IStepFunctionsTaskResource, iam.IGrantable {
 
  /**
@@ -215,26 +214,6 @@ export abstract class FunctionBase extends Resource implements IFunction {
  return !!this._connections;
  }
 
- /**
- * Returns a RuleTarget that can be used to trigger this Lambda as a
- * result from a CloudWatch event.
- */
- public asEventRuleTarget(ruleArn: string, ruleId: string): events.EventRuleTargetProps {
- const permissionId = `AllowEventRule${ruleId}`;
- if (!this.node.tryFindChild(permissionId)) {
- this.addPermission(permissionId, {
- action: 'lambda:InvokeFunction',
- principal: new iam.ServicePrincipal('events.amazonaws.com'),
- sourceArn: ruleArn
- });
- }
-
- return {
- id: this.node.id,
- arn: this.functionArn,
- };
- }
-
  /**
  * Grant the given identity permissions to invoke this Lambda
  */

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

@@ -1,5 +1,4 @@
-import { countResources, expect, haveResource, MatchStyle, ResourcePart } from '@aws-cdk/assert';
-import events = require('@aws-cdk/aws-events');
+import { expect, haveResource, MatchStyle, ResourcePart } from '@aws-cdk/assert';
 import iam = require('@aws-cdk/aws-iam');
 import logs = require('@aws-cdk/aws-logs');
 import sqs = require('@aws-cdk/aws-sqs');
@@ -257,57 +256,6 @@ export = {
  },
  },
 
- 'Lambda can serve as EventRule target, permission gets added'(test: Test) {
- // GIVEN
- const stack = new cdk.Stack();
- const fn = newTestLambda(stack);
- const rule1 = new events.EventRule(stack, 'Rule', { scheduleExpression: 'rate(1 minute)' });
- const rule2 = new events.EventRule(stack, 'Rule2', { scheduleExpression: 'rate(5 minutes)' });
-
- // WHEN
- rule1.addTarget(fn);
- rule2.addTarget(fn);
-
- // THEN
- const lambdaId = "MyLambdaCCE802FB";
-
- expect(stack).to(haveResource('AWS::Lambda::Permission', {
- "Action": "lambda:InvokeFunction",
- "FunctionName": {
- "Fn::GetAtt": [
- lambdaId,
- "Arn"
- ]
- },
- "Principal": "events.amazonaws.com",
- "SourceArn": { "Fn::GetAtt": [ "Rule4C995B7F", "Arn" ] }
- }));
-
- expect(stack).to(haveResource('AWS::Lambda::Permission', {
- "Action": "lambda:InvokeFunction",
- "FunctionName": {
- "Fn::GetAtt": [
- lambdaId,
- "Arn"
- ]
- },
- "Principal": "events.amazonaws.com",
- "SourceArn": { "Fn::GetAtt": [ "Rule270732244", "Arn" ] }
- }));
-
- expect(stack).to(countResources('AWS::Events::Rule', 2));
- expect(stack).to(haveResource('AWS::Events::Rule', {
- "Targets": [
- {
- "Arn": { "Fn::GetAtt": [ lambdaId, "Arn" ] },
- "Id": "MyLambda"
- }
- ]
- }));
-
- test.done();
- },
-
  'Lambda code can be read from a local directory via an asset'(test: Test) {
  // GIVEN
  const stack = new cdk.Stack();