When I am trying to do a custom lambda trigger it's not working, but the Pre Authentication trigger works fine. Earlier it was working fine but suddenly it stopped working. I have also tried to create a new userpool in a different region, but the problem is there too. I have checked the permissions, the lambda has all the required permissions. Are these triggers stored somewhere or kept track of, so that once the trigger starts working the pending ones can be processed again?
Lambda code:
exports.handler = async (event, context, callback) => {
if(event.userPoolId === process.env.USER_POOL_ID) {
if(event.triggerSource === "CustomMessage_SignUp") {
const { codeParameter } = event.request
const { userName, region } = event
const { clientId } = event.callerContext
const { email } = event.request.userAttributes
const url = 'some url'
const link = `here`
event.response.emailSubject = "Your verification link";
event.response.emailMessage = `Thank you for signing up. Click ${link} to verify your email.`;
}
}
callback(null, event);
};
Related
I tried every possible solution on the internet with no hope
What I am trying to do is simply use aws lambda functions (through the aws console) to fetch user fcm token from lets say DynamoDB (not included in the question), use that token to create endpointArn, send push to that specific device
I tested to send Using SNS console and the push gets to the device successfully but I failed to get it to the device using Lambda functions although it gives success status and message ID
Here is the code I used
// Load the AWS SDK for Node.js
var AWS = require('aws-sdk');
// Set region
AWS.config.update({region: 'us-east-1'});
const sns = new AWS.SNS()
const sampleMessage = {
"GCM": {
"notification": {
"body": "Sample message for Android endpoints",
"title":"Title Test"
}
}
}
exports.handler = async (event) => {
const snsPayload = JSON.stringify(sampleMessage);
const response = {
statusCode: 200,
body: JSON.stringify('Hello from Lambda!'),
};
const params = {
PlatformApplicationArn: '<Platform Arn>',
Token: '<FCM Token>'
};
try {
const endpointData = await sns.createPlatformEndpoint(params).promise();
const paramsMessage = {
Message: snsPayload,
TargetArn: endpointData.EndpointArn
};
var publishTextPromise = await sns.publish(paramsMessage).promise();
response.MessageId = publishTextPromise.MessageId;
response.result = 'Success';
}
catch (e) {
console.log(e.stack)
response.result = 'Error'
}
return response;
};
After some trials and errors I figured out the solution for my own question
1- The GCM part of the payload should be a string not a json
2- The message parameter should have an attribute that explicitly sets the mime type of the payload to Json
Taking all that into consideration
const GCM_data = {
'notification': {
'body': 'Hellow from lambda function',
'title': 'Notification Title'
}
}
const data = {
"GCM": JSON.stringify(GCM_data)
}
const snsPayload = JSON.stringify(data)
and the params should look like
const paramsMessage = {
Message: snsPayload,
TargetArn: endpointData.EndpointArn,
MessageStructure: 'json'
};
and this will work :)
I've set up a user pool in Amazon Cognito for my web application. The application is not meant to be public and only specific users are allowed to sign in. The policies of that user pool in the Amazon Console allow only administrators to create new users.
I've implemented sign in through Facebook and Google. Cognito does indeed let users sign into the application with these federated identity providers, which is great. However, it seems that anybody with a Facebook or Google account can sign themselves up now.
So, on one hand, people can not create their own user with regular Cognito credentials but, on the other hand, they can create a new user in Cognito if they use a federated identity provider.
Is there a way to restrict signing into my application with Facebook or Google to only users that already exist in the user pool? That way, administrators would still be able to control who exactly can access the application. I would like to use the email shared by the federated identity provider to check if they are allowed to sign in.
The application is set up with CloudFront. I've written a Lambda that intercepts origin requests to check for tokens in cookies and authorize access based on the validity of the access token.
I would like to avoid writing additional code to prevent users to sign themselves up with Facebook or Google but if there is no other way, I'll update the Lambda.
So, here is the pre sign-up Lambda trigger I ended up writing. I took the time to use async/await instead of Promises. It works nicely, except that there is a documented bug where Cognito forces users who use external identity providers for the first time to sign up and then sign in again (so they see the auth page twice) before they can access the application. I have an idea on how to fix this but in the meantime the Lambda below does what I wanted. Also, it turns out that the ID that comes from Login With Amazon is not using the correct case, so I had to re-format that ID by hand, which is unfortunate. Makes me feel like the implementation of the triggers for Cognito is a bit buggy.
const PROVIDER_MAP = new Map([
['facebook', 'Facebook'],
['google', 'Google'],
['loginwithamazon', 'LoginWithAmazon'],
['signinwithapple', 'SignInWithApple']
]);
async function getFirstCognitoUserWithSameEmail(event) {
const { region, userPoolId, request } = event;
const AWS = require('aws-sdk');
const cognito = new AWS.CognitoIdentityServiceProvider({
region
});
const parameters = {
UserPoolId: userPoolId,
AttributesToGet: ['sub', 'email'], // We don't really need these attributes
Filter: `email = "${request.userAttributes.email}"` // Unfortunately, only one filter can be applied at once
};
const listUserQuery = await cognito.listUsers(parameters).promise();
if (!listUserQuery || !listUserQuery.Users) {
return { error: 'Could not get list of users.' };
}
const { Users: users } = listUserQuery;
const cognitoUsers = users.filter(
user => user.UserStatus !== 'EXTERNAL_PROVIDER' && user.Enabled
);
if (cognitoUsers.length === 0) {
console.log('No existing enabled Cognito user with same email address found.');
return {
error: 'User is not allowed to sign up.'
};
}
if (cognitoUsers.length > 1) {
cognitoUsers.sort((a, b) =>
a.UserCreateDate > b.UserCreateDate ? 1 : -1
);
}
console.log(
`Found ${cognitoUsers.length} enabled Cognito user(s) with same email address.`
);
return { user: cognitoUsers[0], error: null };
}
// Only external users get linked with Cognito users by design
async function linkExternalUserToCognitoUser(event, existingUsername) {
const { userName, region, userPoolId } = event;
const [
externalIdentityProviderName,
externalIdentityUserId
] = userName.split('_');
if (!externalIdentityProviderName || !externalIdentityUserId) {
console.error(
'Invalid identity provider name or external user ID. Should look like facebook_123456789.'
);
return { error: 'Invalid external user data.' };
}
const providerName = PROVIDER_MAP.get(externalIdentityProviderName);
let userId = externalIdentityUserId;
if (providerName === PROVIDER_MAP.get('loginwithamazon')) {
// Amazon IDs look like amzn1.account.ABC123DEF456
const [part1, part2, amazonId] = userId.split('.');
const upperCaseAmazonId = amazonId.toUpperCase();
userId = `${part1}.${part2}.${upperCaseAmazonId}`;
}
const AWS = require('aws-sdk');
const cognito = new AWS.CognitoIdentityServiceProvider({
region
});
console.log(`Linking ${userName} (ID: ${userId}).`);
const parameters = {
// Existing user in the user pool to be linked to the external identity provider user account.
DestinationUser: {
ProviderAttributeValue: existingUsername,
ProviderName: 'Cognito'
},
// An external identity provider account for a user who does not currently exist yet in the user pool.
SourceUser: {
ProviderAttributeName: 'Cognito_Subject',
ProviderAttributeValue: userId,
ProviderName: providerName // Facebook, Google, Login with Amazon, Sign in with Apple
},
UserPoolId: userPoolId
};
// See https://docs.aws.amazon.com/cognito-user-identity-pools/latest/APIReference/API_AdminLinkProviderForUser.html
await cognito.adminLinkProviderForUser(parameters).promise();
console.log('Successfully linked external identity to user.');
// TODO: Update the user created for the external identity and update the "email verified" flag to true. This should take care of the bug where users have to sign in twice when they sign up with an identity provider for the first time to access the website.
// Bug is documented here: https://forums.aws.amazon.com/thread.jspa?threadID=267154&start=25&tstart=0
return { error: null };
}
module.exports = async (event, context, callback) => {
// See event structure at https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-identity-pools-working-with-aws-lambda-triggers.html
const { triggerSource } = event;
switch (triggerSource) {
default: {
return callback(null, event);
}
case 'PreSignUp_ExternalProvider': {
try {
const {
user,
error: getUserError
} = await getFirstCognitoUserWithSameEmail(event);
if (getUserError) {
console.error(getUserError);
return callback(getUserError, null);
}
const {
error: linkUserError
} = await linkExternalUserToCognitoUser(event, user.Username);
if (linkUserError) {
console.error(linkUserError);
return callback(linkUserError, null);
}
return callback(null, event);
} catch (error) {
const errorMessage =
'An error occurred while signing up user from an external identity provider.';
console.error(errorMessage, error);
return callback(errorMessage, null);
}
}
}
};
There is a way to do this but you will need to write some code - there is no out-of-the-box solution.
You will need to write a lambda and connect it to the Cognito Pre-Signup trigger.
https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-pre-sign-up.html
The trigger has three different sources of event; PreSignUp_SignUp, PreSignUp_AdminCreateUser and PreSignUp_ExternalProvider.
Your lambda should check you have the PreSignUp_ExternalProvider event. For these events, use the Cognito SDK to look the user up in your existing pool. If the user exists, return the event. If the user does not exist, return a string (error message).
I will paste my own Pre-Signup trigger here. It does not do what you need it to, but all the main components you need are there. You can basically hack it into doing what you require.
const AWS = require("aws-sdk");
const cognito = new AWS.CognitoIdentityServiceProvider();
exports.handler = (event, context, callback) => {
function checkForExistingUsers(event, linkToExistingUser) {
console.log("Executing checkForExistingUsers");
var params = {
UserPoolId: event.userPoolId,
AttributesToGet: ['sub', 'email'],
Filter: "email = \"" + event.request.userAttributes.email + "\""
};
return new Promise((resolve, reject) =>
cognito.listUsers(params, (err, result) => {
if (err) {
reject(err);
return;
}
if (result && result.Users && result.Users[0] && result.Users[0].Username && linkToExistingUser) {
console.log("Found existing users: ", result.Users);
if (result.Users.length > 1){
result.Users.sort((a, b) => (a.UserCreateDate > b.UserCreateDate) ? 1 : -1);
console.log("Found more than one existing users. Ordered by createdDate: ", result.Users);
}
linkUser(result.Users[0].Username, event).then(result => {
resolve(result);
})
.catch(error => {
reject(err);
return;
});
} else {
resolve(result);
}
})
);
}
function linkUser(sub, event) {
console.log("Linking user accounts with target sub: " + sub + "and event: ", event);
//By default, assume the existing account is a Cognito username/password
var destinationProvider = "Cognito";
var destinationSub = sub;
//If the existing user is in fact an external user (Xero etc), override the the provider
if (sub.includes("_")) {
destinationProvider = sub.split("_")[0];
destinationSub = sub.split("_")[1];
}
var params = {
DestinationUser: {
ProviderAttributeValue: destinationSub,
ProviderName: destinationProvider
},
SourceUser: {
ProviderAttributeName: 'Cognito_Subject',
ProviderAttributeValue: event.userName.split("_")[1],
ProviderName: event.userName.split("_")[0]
},
UserPoolId: event.userPoolId
};
console.log("Parameters for adminLinkProviderForUser: ", params);
return new Promise((resolve, reject) =>
cognito.adminLinkProviderForUser(params, (err, result) => {
if (err) {
console.log("Error encountered whilst linking users: ", err);
reject(err);
return;
}
console.log("Successfully linked users.");
resolve(result);
})
);
}
console.log(JSON.stringify(event));
if (event.triggerSource == "PreSignUp_SignUp" || event.triggerSource == "PreSignUp_AdminCreateUser") {
checkForExistingUsers(event, false).then(result => {
if (result != null && result.Users != null && result.Users[0] != null) {
console.log("Found at least one existing account with that email address: ", result);
console.log("Rejecting sign-up");
//prevent sign-up
callback("An external provider account alreadys exists for that email address", null);
} else {
//proceed with sign-up
callback(null, event);
}
})
.catch(error => {
console.log("Error checking for existing users: ", error);
//proceed with sign-up
callback(null, event);
});
}
if (event.triggerSource == "PreSignUp_ExternalProvider") {
checkForExistingUsers(event, true).then(result => {
console.log("Completed looking up users and linking them: ", result);
callback(null, event);
})
.catch(error => {
console.log("Error checking for existing users: ", error);
//proceed with sign-up
callback(null, event);
});
}
};
I would like to migrate users from userPool 1 to userPool 2 with the migration user lambda in AWS Console function. In order to do it, I have used the script provided by AWS but I can't find how I can use authenticateUser for instance. It is not defined when executed.
The migration lambda is executed.
authenticateUser is not defined
I have also tried to create a layer, imported succesfully and set the layer in my lambda function but cannot make it work too.
exports.handler = (event, context, callback) => {
var user;
if ( event.triggerSource == "UserMigration_Authentication" ) {
// authenticate the user with your existing user directory service
user = authenticateUser(event.userName, event.request.password);
if ( user ) {
event.response.userAttributes = {
"email": user.emailAddress,
"email_verified": "true"
};
event.response.finalUserStatus = "CONFIRMED";
event.response.messageAction = "SUPPRESS";
context.succeed(event);
}
else {
// Return error to Amazon Cognito
callback("Bad password");
}
}
else if ( event.triggerSource == "UserMigration_ForgotPassword" ) {
// Lookup the user in your existing user directory service
user = lookupUser(event.userName);
if ( user ) {
event.response.userAttributes = {
"email": user.emailAddress,
// required to enable password-reset code to be sent to user
"email_verified": "true"
};
event.response.messageAction = "SUPPRESS";
context.succeed(event);
}
else {
// Return error to Amazon Cognito
callback("Bad password");
}
}
else {
// Return error to Amazon Cognito
callback("Bad triggerSource " + event.triggerSource);
}
};
authenticateUser is not defined
My question is : how do we import this function ?
Thanks a lot.
That sample code is for migrating a user from a legacy database, and the authenticateUser, lookupUser functions are just abstractions for your business logic (which AWS can't write for you). For instance if you have to migrate from a legacy database (not a user pool), then you would lookup their user in your table, grab their salt, hash the password passed in to the migration trigger using the same logic you did in your legacy authentication method, compare it against the stored hashed password in your legacy database, etc. (It gets a little simpler if you were storing passwords in plaintext, but let's not consider that.)
Here's a snippet that should do most of the migration for you. Someone asked a similar question on Github and referenced this StackOverflow issue.
const AWS = require('aws-sdk');
const cognitoIdentity = new AWS.CognitoIdentityServiceProvider({ region: '<your-region-here>' });
const UserPoolId = process.env.deprecatedUserPoolId;
exports.handler = async (event) => {
const { userName } = event;
const getUserParams = {
Username: userName,
UserPoolId
};
try {
const user = await cognitoIdentity.adminGetUser(getUserParams).promise();
//TODO: if you have custom attributes, grab them from the user variable and store them in the response below
event.response = { finalUserStatus: "CONFIRMED" }
return event;
} catch (e) {
throw e; //no user to migrate, give them an error in the client
}
};
I am trying to use AWS mobile backend (using lambda function) to insert into dynamoDB (also configured at the mobile backend) but with no success so far.
The relevant code:
'use strict';
console.log("Loading function");
const AWS = require('aws-sdk');
const docClient = new AWS.DynamoDB.DocumentClient({region:process.env.MOBILE_HUB_PROJECT_REGION});
exports.handler = function(event, context, callback) {
var responseCode = 200;
var requestBody, pathParams, queryStringParams, headerParams, stage,
stageVariables, cognitoIdentityId, httpMethod, sourceIp, userAgent,
requestId, resourcePath;
console.log("request: " + JSON.stringify(event));
// Request Body
requestBody = event.body;
if (requestBody !== undefined && requestBody !== null) {
// Set 'test-status' field in the request to test sending a specific response status code (e.g., 503)
responseCode = JSON.parse(requestBody)['test-status'];
}
// Path Parameters
pathParams = event.path;
// Query String Parameters
queryStringParams = event.queryStringParameters;
// Header Parameters
headerParams = event.headers;
if (event.requestContext !== null && event.requestContext !== undefined) {
var requestContext = event.requestContext;
// API Gateway Stage
stage = requestContext.stage;
// Unique Request ID
requestId = requestContext.requestId;
// Resource Path
resourcePath = requestContext.resourcePath;
var identity = requestContext.identity;
// Amazon Cognito User Identity
cognitoIdentityId = identity.cognitoIdentityId;
// Source IP
sourceIp = identity.sourceIp;
// User-Agent
userAgent = identity.userAgent;
}
// API Gateway Stage Variables
stageVariables = event.stageVariables;
// HTTP Method (e.g., POST, GET, HEAD)
httpMethod = event.httpMethod;
// TODO: Put your application logic here...
let params = {
Item:{
"prop1":0,
"prop2":"text"
},
TableName:"testTable"
};
docClient.put(params, function(data, err){
if(err)
responseCode = 500;
else
{
responseCode = 200;
context.succeed(data);
}
});
// For demonstration purposes, we'll just echo these values back to the client
var responseBody = {
requestBody : requestBody,
pathParams : pathParams,
queryStringParams : queryStringParams,
headerParams : headerParams,
stage : stage,
stageVariables : stageVariables,
cognitoIdentityId : cognitoIdentityId,
httpMethod : httpMethod,
sourceIp : sourceIp,
userAgent : userAgent,
requestId : requestId,
resourcePath : resourcePath
};
var response = {
statusCode: responseCode,
headers: {
"x-custom-header" : "custom header value"
},
body: JSON.stringify(responseBody)
};
console.log("response: " + JSON.stringify(response))
context.succeed(response);
};
this doesn't put the item to the table for some reason.
I gave the necessary permissions using the roles part, anything I am missing?
**responseCode is only for testing purposes.
Edit:
tried AWS node.js lambda request dynamodb but no response (no err, no return data) and doesn't work either.
Edit2:
Added the full handler code. (it the default generated code when creating first AWS lambda).
I have refactored some bits of your code to look much simpler and use async/await (make sure to select Node 8.10 as the running environment for your function) instead of callbacks. I also got rid of the context and callback parameters, as they were used for older versions of NodeJS. Once you're using Node 8+, async/await should be the default option.
Also, it is possible to chain a .promise() on docClient.putItem, so you can easily await on it, making your code way simpler. I have left only the DynamoDB part (which is what is relevant to your question)
'use strict';
console.log("Loading function");
const AWS = require('aws-sdk');
const docClient = new AWS.DynamoDB.DocumentClient({region:process.env.MOBILE_HUB_PROJECT_REGION});
exports.handler = async (event) => {
let params = {
Item:{
"prop0":1,
"prop2":"text"
},
TableName:"testTable"
};
try {
await docClient.put(params).promise();
} catch (e) {
console.log(e)
return {
messsage: e.message
}
}
return { message: 'Data inserted successfully' };
};
Things to keep in mind if still it does not work:
Make sure your Lambda function has the right permissions to insert items on DynamoDB (AmazonDynamoDBFullAccess will do it)
You ALWAYS have to provide the partition key when inserting items to DynamoDB. On your example, the JSON only has two properties: prop1 and prop2. If none of them are the partition key, your code will certainly fail.
Make sure you table also exists
If you code fails, just check CloudWatch logs as any exception is now captured and printed out on the console.
The reason why no data is written in the table is because the call to DynamoDB put is asynchronous and will return by calling your callback. But during that time, the rest of the code continues to execute and your function eventually finish before the call to DynamoDB has a chance to complete.
You can use the await / async keywords to make your code sychronous :
async function writeToDynamoDB(params) {
return new Promise((resolve,reject) => {
docClient.put(params, function(data, err){
if(err)
reject(500);
else
resolve(data);
});
});
}
let params = ...
var data = await writeToDynamoDB(params)
You can find sample code I wrote (in Typescript) at https://github.com/sebsto/maxi80-alexa/blob/master/lambda/src/DDBController.ts
There's a way to send an email other than the one specified in the "Message customisation" tab on Cognito user pool?
I would like to use different email based on some parameters.
E.g.
verification#my-service.com for verification email
welcome#my-service.com for welcome email
You can go to the general settings in Cognito then click on triggers. There you can select Post Confirmation lambda function(this example in node) to send the email. In the lambda function you can make the subject whatever you like and change from email address.
var aws = require('aws-sdk');
var ses = new aws.SES();
exports.handler = function(event, context) {
console.log(event);
if (event.request.userAttributes.email) {
// Pull another attribute if you want
sendEmail(event.request.userAttributes.email,
"Congratulations "+event.userName+", you have been registered!"
, function(status) {
context.done(null, event);
});
} else {
// Nothing to do, the user's email ID is unknown
console.log("Failed");
context.done(null, event);
}
};
function sendEmail(to, body, completedCallback) {
var eParams = {
Destination: {
ToAddresses: [to]
},
Message: {
Body: {
Text: {
Data: body
}
},
Subject: {
Data: "Welcome to My Service!"
}
},
Source: "welcome#my-service.com"
};
var email = ses.sendEmail(eParams, function(err, data){
if (err) {
console.log(err);
} else {
console.log("===EMAIL SENT===");
}
completedCallback('Email sent');
});
console.log("EMAIL CODE END");
};
You will also have to set up SES.
If you want to handle all emails yourself, you can specify this with a CustomEmailSender Lambda. This trigger isn't currently available through the AWS Console, but you can specify it with the CLI or CDK/CloudFormation. See the docs here.
Those docs are pretty terrible though. The gist is that you'll be given a code property on the event, which is a base64-encoded blob that was encrypted with the KMS key you specified on your user pool. Depending on the triggering event, this is the verification code, temporary password, etc, generated by Cognito. Here's a simplified version of what my Lambda looks like:
import { buildClient, CommitmentPolicy, KmsKeyringNode } from '#aws-crypto/client-node';
const { decrypt } = buildClient(CommitmentPolicy.REQUIRE_ENCRYPT_ALLOW_DECRYPT);
const kmsKeyring = new KmsKeyringNode({
keyIds: [process.env.COGNITO_EMAILER_KEY_ARN]
});
export async function lambdaHandler(event, context) {
try {
let payload = '';
if (event.request.code) {
const { plaintext, messageHeader } = await decrypt(
kmsKeyring,
Buffer.from(event.request.code, "base64")
);
if (event.userPoolId !== messageHeader.encryptionContext["userpool-id"]) {
console.error("Encryption context does not match expected values!");
return;
}
payload = plaintext.toString();
}
let messageHtml = "";
switch (event.triggerSource) {
case "CustomEmailSender_SignUp": {
const verificationCode = payload;
messageHtml = `<p>Use this code to verify your email: ${verificationCode}</p>`;
break;
}
case "CustomEmailSender_AdminCreateUser":
case "CustomEmailSender_ResendCode": {
const tempPassword = payload;
messageHtml = `<p>Your temporary password is ${tempPassword}</p>`;
break;
}
default: {
console.warn("unhandled trigger:", event.triggerSource);
return;
}
}
await sendEmail({
subject: "Automated message",
to: event.request.userAttributes.email,
messageHtml,
});
return true;
} catch (err) {
console.error(err.message);
process.exit(1);
}
}