feat(new-ex): add AppSync triggering Event Bridge Example

typescript/appsync-graphql-eventbridge/README.md

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+# AppSync GraphQL sending events to Event Bridge
+
+This an example of an AppSync GraphQL API sending events to Event Bridge and trigerring a rule that invokes a Lambda function
+
+![Overview](media.png)
+
+## Build
+
+To build this app, you need run the following commands from the root folder:
+
+```bash
+npm install -g aws-cdk
+npm install
+npm run build
+```
+
+This will install the necessary CDK, then this example's dependencies, and then build your TypeScript files and your CloudFormation template.
+
+## Deploy
+
+Run `cdk deploy`. This will deploy / redeploy your Stack to your AWS Account.
+
+After the deployment you will see the API's URL, which represents the url you can then use.
+
+## Synthesize Cloudformation Template
+
+To see the Cloudformation template generated by the CDK, run `cdk synth`, then check the output file in the "cdk.out" directory.
+
+## The Component Structure
+
+This Stack contains:
+
+- a **GraphQL API** with an API Key (Use with caution, each key is only valid for 7 days.)
+- a **GraphQL Schema** with a Mutation that sends an event to Event Bridge
+- an **IAM Role** that allows AppSync to send events to your Event Bus
+- an **AppSync DataSource**, connecting your API to Event Bridge using a HTTP Resolver
+- an **AppSync Resolver** for a Mutation `putEvent` that sends a custom event to Event Bridge
+- an **Event Rule** that listens for the custom event comming from AppSync and triggers a Lambda function in response to the event
+- a **Lambda** function that just prints out the event, you can confirm it's triggered by the Event Bridge's rule by checking the function logs on CloudWatch.

typescript/appsync-graphql-eventbridge/cdk.json

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+{
+  "app": "node index"
+}

typescript/appsync-graphql-eventbridge/index.ts

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+import cdk = require("@aws-cdk/core");
+import {
+  CfnGraphQLApi,
+  CfnApiKey,
+  CfnGraphQLSchema,
+  CfnDataSource,
+  CfnResolver
+} from "@aws-cdk/aws-appsync";
+import { Role, ServicePrincipal, PolicyStatement } from "@aws-cdk/aws-iam";
+import { Rule } from "@aws-cdk/aws-events";
+import lambda = require("@aws-cdk/aws-lambda");
+import targets = require("@aws-cdk/aws-events-targets");
+
+export class AppSyncCdkStack extends cdk.Stack {
+  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
+    super(scope, id, props);
+
+    const appSync2EventBridgeGraphQLApi = new CfnGraphQLApi(
+      this,
+      "AppSync2EventBridgeApi",
+      {
+        name: "AppSync2EventBridge-API",
+        authenticationType: "API_KEY"
+      }
+    );
+
+    new CfnApiKey(this, "AppSync2EventBridgeApiKey", {
+      apiId: appSync2EventBridgeGraphQLApi.attrApiId
+    });
+
+    const apiSchema = new CfnGraphQLSchema(this, "ItemsSchema", {
+      apiId: appSync2EventBridgeGraphQLApi.attrApiId,
+      definition: `type Event {
+        result: String
+      }
+
+      type Mutation {
+        putEvent(event: String!): Event
+      }
+
+      type Query {
+        getEvent: Event
+      }
+
+      schema {
+        query: Query
+        mutation: Mutation
+      }`
+    });
+
+    const appsyncEventBridgeRole = new Role(this, "AppSyncEventBridgeRole", {
+      assumedBy: new ServicePrincipal("appsync.amazonaws.com")
+    });
+
+    appsyncEventBridgeRole.addToPolicy(
+      new PolicyStatement({
+        resources: ["*"],
+        actions: ["events:Put*"]
+      })
+    );
+
+    const dataSource = new CfnDataSource(this, "ItemsDataSource", {
+      apiId: appSync2EventBridgeGraphQLApi.attrApiId,
+      name: "EventBridgeDataSource",
+      type: "HTTP",
+      httpConfig: {
+        authorizationConfig: {
+          authorizationType: "AWS_IAM",
+          awsIamConfig: {
+            signingRegion: this.region,
+            signingServiceName: "events"
+          }
+        },
+        endpoint: "https://events." + this.region + ".amazonaws.com/"
+      },
+      serviceRoleArn: appsyncEventBridgeRole.roleArn
+    });
+
+    const putEventResolver = new CfnResolver(this, "PutEventMutationResolver", {
+      apiId: appSync2EventBridgeGraphQLApi.attrApiId,
+      typeName: "Mutation",
+      fieldName: "putEvent",
+      dataSourceName: dataSource.name,
+      requestMappingTemplate: `{
+        "version": "2018-05-29",
+        "method": "POST",
+        "resourcePath": "/",
+        "params": {
+          "headers": {
+            "content-type": "application/x-amz-json-1.1",
+            "x-amz-target":"AWSEvents.PutEvents"
+          },
+          "body": {
+            "Entries":[ 
+              {
+                "Source":"appsync",
+                "EventBusName": "default",
+                "Detail":"{ \\\"event\\\": \\\"$ctx.arguments.event\\\"}",
+                "DetailType":"Event Bridge via GraphQL"
+               }
+            ]
+          }
+        }
+      }`,
+      responseMappingTemplate: `## Raise a GraphQL field error in case of a datasource invocation error
+      #if($ctx.error)
+        $util.error($ctx.error.message, $ctx.error.type)
+      #end
+      ## if the response status code is not 200, then return an error. Else return the body **
+      #if($ctx.result.statusCode == 200)
+          ## If response is 200, return the body.
+          {
+            "result": "$util.parseJson($ctx.result.body)"
+          }
+      #else
+          ## If response is not 200, append the response to error block.
+          $utils.appendError($ctx.result.body, $ctx.result.statusCode)
+      #end`
+    });
+    putEventResolver.addDependsOn(apiSchema);
+
+    const echoLambda = new lambda.Function(this, "echoFunction", {
+      code: lambda.Code.fromInline(
+        "exports.handler = (event, context) => { console.log(event); context.succeed(event); }"
+      ),
+      handler: "index.handler",
+      runtime: lambda.Runtime.NODEJS_10_X
+    });
+
+    const rule = new Rule(this, "AppSyncEventBridgeRle", {
+      eventPattern: {
+        source: ["appsync"]
+      }
+    });
+    rule.addTarget(new targets.LambdaFunction(echoLambda));
+  }
+}
+
+const app = new cdk.App();
+new AppSyncCdkStack(app, "AppSyncEventBridge");
+app.synth();

typescript/appsync-graphql-eventbridge/package.json

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+{
+  "name": "appsync-graphql-eventbridge",
+  "version": "1.0.0",
+  "description": "Sends events to Event Bridge via an AppSync GraphQL API",
+  "private": true,
+  "bin": {
+    "cdk": "bin/cdk.js"
+  },
+  "scripts": {
+    "build": "tsc",
+    "watch": "tsc -w",
+    "cdk": "cdk"
+  },
+  "license": "MIT",
+  "devDependencies": {
+    "@types/node": "10.17.0",
+    "typescript": "~3.7.2",
+    "ts-node": "^8.1.0",
+    "aws-cdk": "^1.18.0"
+  },
+  "dependencies": {
+    "@aws-cdk/aws-appsync": "*",
+    "@aws-cdk/aws-iam": "*",
+    "@aws-cdk/aws-events": "*",
+    "@aws-cdk/aws-events-targets": "*",
+    "@aws-cdk/aws-lambda": "*",
+    "@aws-cdk/core": "*",
+    "source-map-support": "^0.5.9"
+  }
+}

typescript/appsync-graphql-eventbridge/tsconfig.json

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+{
+  "compilerOptions": {
+    "target":"ES2018",
+    "module": "commonjs",
+    "lib": ["es2016", "es2017.object", "es2017.string"],
+    "declaration": true,
+    "strict": true,
+    "noImplicitAny": true,
+    "strictNullChecks": true,
+    "noImplicitThis": true,
+    "alwaysStrict": true,
+    "noUnusedLocals": false,
+    "noUnusedParameters": false,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": false,
+    "inlineSourceMap": true,
+    "inlineSources": true,
+    "experimentalDecorators": true,
+    "strictPropertyInitialization":false
+  },
+  "exclude": ["cdk.out"]
+}