amplify add trigger

[rawadrifai]

Is your feature request related to a problem? Please describe.
No. Just a convenience and a step towards no console at all.

Describe the solution you'd like
add a command amplify add trigger
It takes a source and a destination. The destination is a lambda.
The source can be cognito triggers, dynamodb table

Describe alternatives you've considered
I do it manually in the console. Not sure if there's a way to include triggers in an amplify project.

Additional context
I love Amplify and would like to see it completely console-less.

[eelzinaty]

That would be a great addition 👍

For now, to achieve this I create a function to handle the trigger, PostConfirm. In the generated stack for the function I add four things:
1- Permission for Cognito to invoke Lambda:

"UserPoolPostConfirmLambdaInvokePermission": {
			"Type": "AWS::Lambda::Permission",
			"Properties": {
				"Action": "lambda:invokeFunction",
				"Principal": "cognito-idp.amazonaws.com",
				"FunctionName": {
					"Fn::GetAtt": [
						"LambdaFunction",
						"Arn"
					]
				},
				"SourceArn": {
					"Fn::Sub": [
						"arn:aws:cognito-idp:${region}:${account}:userpool/${userpool}",
						{
							"region": {
								"Ref": "AWS::Region"
							},
							"account": {
								"Ref": "AWS::AccountId"
							},
							"userpool": {
								"Ref": "cognitoUserPoolId"
							}
						}
					]
				}
			}
		}

2- I create inline function that is repsonsible for connecting the Lambda function with cognito trigger.

"UserPoolPostConfirmLambdaFunction": {
			"Type": "AWS::Lambda::Function",
			"Properties": {
				"Code": {
					"ZipFile": {
						"Fn::Join": [
							"\n",
							[
								"const aws = require('aws-sdk');",
								"exports.handler = async (event, context) => {",
								"    try {",
								"        console.log(event.RequestType);",
								"        console.log(event.ResourceProperties);",
								"        if (event.RequestType == 'Delete') {",
								"            await sendResponse(event, context, 'SUCCESS', {});",
								"            context.done();",
								"        }",
								"       if (event.RequestType == 'Update' || event.RequestType == 'Create') {",
								"           const identity = new aws.CognitoIdentityServiceProvider({ apiVersion: '2016-04-18', region: event.ResourceProperties.region });",
								"           const params = {",
								"               UserPoolId: event.ResourceProperties.userpoolId,",
								"               LambdaConfig: {",
								"                   PostConfirmation: event.ResourceProperties.lambdaname",
								"               }",
								"           };",
								"           console.log(params);",
								"           await identity.updateUserPool(params).promise()",
								"           await sendResponse(event, context, 'SUCCESS', {});",
								"           context.done();",
								"       }",
								"    }",
								"    catch (err) {",
								"        console.log(err);",
								"        const responseData = { Error: err };",
								"        await sendResponse(event, context, 'FAILED', responseData);",
								"        context.done();",
								"    }",
								"};",
								"async function sendResponse(event, context, responseStatus, responseData, physicalResourceId, noEcho) {",
								"    var responseBody = JSON.stringify({",
								"        Status: responseStatus,",
								"        Reason: 'See the details in CloudWatch Log Stream: ' + context.logStreamName,",
								"        PhysicalResourceId: physicalResourceId || context.logStreamName,",
								"        StackId: event.StackId,",
								"        RequestId: event.RequestId,",
								"        LogicalResourceId: event.LogicalResourceId,",
								"        NoEcho: noEcho || false,",
								"        Data: responseData",
								"    });",
								"    console.log('Response body:', responseBody);",
								"    var https = require('https');",
								"    var url = require('url');",
								"    let parsedUrl;",
								"    try {",
								"        parsedUrl = url.parse(event.ResponseURL);",
								"    } catch (error) {",
								"        throw new Error(`Invalid url ${event.ResponseURL}`);",
								"    }",
								"    let options = {",
								"        hostname: parsedUrl.hostname,",
								"        port: 443,",
								"        path: parsedUrl.path,",
								"        method: 'PUT',",
								"        headers: {",
								"            'content-type': '',",
								"            'content-length': responseBody.length",
								"        }",
								"    };",
								"    return new Promise((resolve, reject) => {",
								"        const clientRequest = https.request(options, incomingMessage => {   ",
								"            let response = {",
								"                statusCode: incomingMessage.statusCode,",
								"                statusMessage: incomingMessage.statusMessage,",
								"                headers: incomingMessage.headers,",
								"                body: []",
								"            };",
								"            incomingMessage.on('data', chunk => {",
								"                response.body.push(chunk);",
								"            });",
								"            incomingMessage.on('end', () => {",
								"                console.log('Status code: ' + response.statusCode);",
								"                console.log('Status message: ' + response.statusMessage);",
								"                try {response.body = response.body.join(); console.log('Response Body: ' + JSON.parse(response.body));} catch(e) {}",
								"                return resolve(response);",
								"            });",
								"        });",
								"        clientRequest.on('error', error => {",
								"            return reject(error);",
								"        });",
								"        if (responseBody) {",
								"            clientRequest.write(responseBody);",
								"        }",
								"        clientRequest.end();",
								"    });",
								"}"
							]
						]
					}
				},
				"Handler": "index.handler",
				"FunctionName": {
					"Fn::If": [
						"ShouldNotCreateEnvResources",
						{
							"Fn::Join": [
								"",
								[
									{
										"Ref": "AppNamePrefix"
									},
									"-",
									"PostConfirmSetup"
								]
							]
						},
						{
							"Fn::Join": [
								"",
								[
									{
										"Ref": "AppNamePrefix"
									},
									"-",
									"PostConfirmSetup",
									"-",
									{
										"Ref": "env"
									}
								]
							]
						}
					]
				},
				"Role": {
					"Fn::GetAtt": [
						"UserPoolPostConfirmLambdaExecutionRole",
						"Arn"
					]
				},
				"Runtime": "nodejs8.10",
				"Timeout": "300"
			}
		}

3- Then I create and IAM role to give the above function the needed permissions to run

"UserPoolPostConfirmLambdaExecutionRole": {
			"Type": "AWS::IAM::Role",
			"Properties": {
				"RoleName": {
					"Fn::If": [
						"ShouldNotCreateEnvResources",
						{
							"Fn::Join": [
								"",
								[
									{
										"Ref": "AppNamePrefix"
									},
									"-",
									"userpool-postconfirm-lambda-iam"
								]
							]
						},
						{
							"Fn::Join": [
								"",
								[
									{
										"Ref": "AppNamePrefix"
									},
									"-",
									"userpool-postconfirm-lambda-iam",
									"-",
									{
										"Ref": "env"
									}
								]
							]
						}
					]
				},
				"AssumeRolePolicyDocument": {
					"Version": "2012-10-17",
					"Statement": [
						{
							"Effect": "Allow",
							"Principal": {
								"Service": [
									"lambda.amazonaws.com"
								]
							},
							"Action": [
								"sts:AssumeRole"
							]
						}
					]
				},
				"Policies": [
					{
						"PolicyName": "cloudWatchPolicy",
						"PolicyDocument": {
							"Version": "2012-10-17",
							"Statement": [
								{
									"Effect": "Allow",
									"Action": [
										"logs:CreateLogGroup",
										"logs:CreateLogStream",
										"logs:PutLogEvents"
									],
									"Resource": {
										"Fn::Sub": [
											"arn:aws:logs:${region}:${account}:log-group:/aws/lambda/${lambda}:log-stream:*",
											{
												"region": {
													"Ref": "AWS::Region"
												},
												"account": {
													"Ref": "AWS::AccountId"
												},
												"lambda": {
													"Fn::If": [
														"ShouldNotCreateEnvResources",
														{
															"Fn::Join": [
																"",
																[
																	{
																		"Ref": "AppNamePrefix"
																	},
																	"-",
																	"PostConfirmSetup"
																]
															]
														},
														{
															"Fn::Join": [
																"",
																[
																	{
																		"Ref": "AppNamePrefix"
																	},
																	"-",
																	"PostConfirmSetup",
																	"-",
																	{
																		"Ref": "env"
																	}
																]
															]
														}
													]
												}
											}
										]
									}
								}
							]
						}
					},
					{
						"PolicyName": "cognitoPolicy",
						"PolicyDocument": {
							"Version": "2012-10-17",
							"Statement": [
								{
									"Effect": "Allow",
									"Action": [
										"cognito-idp:UpdateUserPool"
									],
									"Resource": {
										"Fn::Sub": [
											"arn:aws:cognito-idp:${region}:${account}:userpool/${userpoolid}",
											{
												"region": {
													"Ref": "AWS::Region"
												},
												"account": {
													"Ref": "AWS::AccountId"
												},
												"userpoolid": {
													"Ref": "cognitoUserPoolId"
												}
											}
										]
									}
								}
							]
						}
					}
				]
			}
		}

4- Finally, you need to create a custom resource to call the setup function

"UserPoolPostConfirmFunctionOutputs": {
			"Type": "Custom::LambdaCallout",
			"Properties": {
				"ServiceToken": {
					"Fn::GetAtt": [
						"UserPoolPostConfirmLambdaFunction",
						"Arn"
					]
				},
				"region": {
					"Ref": "AWS::Region"
				},
				"userpoolId": {
					"Ref": "cognitoUserPoolId"
				},
				"lambdaname": {
					"Fn::GetAtt": [
						"LambdaFunction",
						"Arn"
					]
				}
			}
		}

NOTE: you need to provide values for these parameters:
AppNamePrefix : any value
cognitoUserPoolId: you can get this from your auth resource

[yuth]

@rawadrifai I have added this feature-request to support generic lambda function as trigger to our backlog. Our product team will go through and prioritize this.

@eelzinaty Auth RFC talks about some of the triggers that we will support. Please feel free to comment in the RFC

[kaustavghosh06]

@rawadrifai We're actively working on DynamoDB, S3 and Cognito Lambda triggers and I'll update this thread once we release support for it.

[kaustavghosh06]

We've added support for Lambda Trigger support for the dynamo tables managed/added by the CLI using the amplify add storage command. Let me know if you find that useful. Please take a look at https://aws.amazon.com/blogs/mobile/amplify-framework-adds-supports-for-aws-lambda-triggers-in-auth-and-storage-categories/ for more details.

[rawadrifai]

@kaustavghosh06 thanks for the update. Is the Pre Token Generation trigger for Cognito supported?

[julescsv]

We've added support for Lambda Trigger support for the dynamo tables managed/added by the CLI using the amplify add storage command. Let me know if you find that useful. Please take a look at https://aws.amazon.com/blogs/mobile/amplify-framework-adds-supports-for-aws-lambda-triggers-in-auth-and-storage-categories/ for more details.

Awesome work " Amplify team". Is there a reason why the lambda triggers cannot be added to dynamo tables created by "amplify add api" ? that is likely the biggest use case.

[github-actions]

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