I have the following serverless.yaml:
getSth:
handler: src/handlers/getSth.getSth
events:
- http:
path: getSth
method: get
cors: true
private: true
authorizer: authorizerFunc
authorizerFunc:
handler: src/handlers/authorizer.authorizer
getSth handler:
module.exports.getSth = async (event, context) => {
const response = {
statusCode: 200,
body: JSON.stringify({message: "nice you can call this});
}
return response;
}
authorizerFunc:
module.exports.authorizer = async (event, context) => {
console.log('i will fail your authorization');
let response = {
isAuthorized: false,
context: {
stringKey: "value",
numberKey: 1,
booleanKey: true,
arrayKey: ["value1", "value2"],
mapKey: { value1: "value2" },
},
};
return response;
}
That results in getting respons 200 in spite of the fact authorizer should not allow to execute that getSth function. Also console log 'I will fail your authorization' is not logged.
What am I doing wrong ?
I have tried to analyse your code and find several points where you can start digging.
Private functions
The key private: true actually makes API Gateway require an API key. I did now not try myself but perhaps private: true and an authorizer do not go together.
Strange still that you are able to call the function then. How do you call the function? From the CLI or through API Gateway and an API testing tool such as Postman or Insomnia?
Authorizer Configuration
Your authorizer configuration is definitely correct. We do have the very same setup in our code.
Authorizer Events
An authorizer function gets an APIGatewayTokenAuthorizerEvent in and should reply with a APIGatewayAuthorizerResult. The latter looks closely like an IAM statement and we do not use the field isAuthorized: false as per your example. I do not understand where this field is coming from. Our result to allow a request looks more or less like the following:
{
"principalId": "<our auth0 user-id>",
"policyDocument": {
"Version": "2012-10-17",
"Statement": [{
"Action": "execute-api:Invoke",
"Effect": "Allow",
"Resource": "*"
}]
}
}
Note how the field principalId refers to the username we get from our identity provider (Auth0). And in reality looks something like this: auth0|6f84a3z162c72d0d0d000a00.
Further, we can allow or deny the function call via the Effect field which can hold the values Allow or Deny.
Finally, you can specify which resource the caller is permitted to call. For simplicity of this answer I put * there. Of course in the real world you can pull the ARN of the called function from the event and context and pass that into the policy document.
Opinion
We also had a hard way of figuring this out via documentation from AWS. Of course for AWS the preferred integration would be via AWS Cognito (which I also do prefer due to the more streamlined integration. We benefited quite a bit form the use of TypeScript here which we use to enforce types in and out of our Serverless functions. This way it was rather easy to figure out how the response needs to look like.
Background
We use the custom authorizer integration to allow a user base already existing in Auth0 consume our Serverless based APIs via application clients or single page applications.
I'm currently in the process of implementing a subscription mutation within AWS Lambda using AppSync. I want to use IAM and avoid using any other type of AUTH mechanism as I'm calling it within the AWS stack. Unfortunately, I'm receiving the following 403 error:
(Excerpt from an SQS' CloudWatch log)
{
"errorMessage": "Response not successful: Received status code 403",
"name": "ServerError",
"errorType": "UnrecognizedClientException",
"message": "The security token included in the request is invalid."
}
I've tried following these to no avail, but I don't know what I'm missing:
https://medium.com/#jan.hesters/how-to-use-aws-appsync-in-lambda-functions-e593a9cef1d5
https://www.edwardbeazer.com/using-appsync-client-from-lambda/
https://adrianhall.github.io/cloud/2018/10/26/backend-graphql-trigger-appsync/
How to send GraphQL mutation from one server to another?
AWS Appsync + HTTP DataSources + AWS IAM
AWS Appsync Invoke mutate from Lambda?
Here's the code that I'm currently calling it from:
import AWS from "aws-sdk";
import { AWSAppSyncClient } from "aws-appsync";
import { Mutation, mutations } from "./mutations/";
import "cross-fetch/polyfill";
/**
*
*/
AWS.config.update({
region: Config.region,
});
export class AppSyncClient {
client: AWSAppSyncClient<any>;
constructor() {
if (!env.APPSYNC_ENDPOINT) {
throw new Error("APPSYNC_ENDPOINT not defined");
}
/**
* We create the AppSyncClient with the AWS_IAM
* authentication.
*/
this.client = new AWSAppSyncClient({
url: env.APPSYNC_ENDPOINT,
region: Config.region,
auth: {
credentials: AWS.config.credentials!,
type: "AWS_IAM",
},
disableOffline: true,
});
}
/**
* Sends a mutation on the AppSync Client
* #param mutate The Mutation that will be sent with the variables.
* #returns
*/
sendMutation(mutate: Mutation) {
const mutation = mutations[mutate.type] as any;
const variables = mutate.variables;
console.log("Sending the mutation");
console.log("Variables is ", JSON.stringify(variables));
return this.client.mutate({
mutation,
fetchPolicy: "network-only",
variables,
});
}
}
Here's the current IAM from the Lambda SQS:
{
"Statement": [
{
"Action": [
"appsync:GraphQL"
],
"Effect": "Allow",
"Resource": [
"arn:aws:appsync:us-east-2:747936726382:apis/myapi"
]
}
],
"Version": "2012-10-17"
}
I know it is not an IAM problem from the lambda, because I've tried momentarily giving it full access, and I still got the 403 error.
I've also verified that AppSync has the IAM permission configured (as an additional provider).
Do you guys have any ideas? I'm impressed that this is a ghost topic with such little configuraiton references.
I finally nailed it. I went and re-read for third time Adrian Hall's post, and it did lead me to the solution.
Please note that I installed the AWS AppSync client which is not needed but simplifies the process (otherwise you'd have to sign the URL yourself. For that see Adrian Hall's post).
There are a couple of things:
You need to polyfill "fetch" by including either cross-fetch (Otherwise you're going to get hit by Invariant Violation from the Apollo Client which AppSync internally uses).
You need to pass the lambda's internal IAM credentials (Which I didn't even know existed) to the configuration portion of the AppSyncClient.
You need to add the proper permission to the IAM role of the lambda, in this case: ["appsync:GraphQL"] for the action.
Here's some code:
This is the AppSync code.
// The code is written in TypeScript.
// https://adrianhall.github.io/cloud/2018/10/26/backend-graphql-trigger-appsync/
// https://www.edwardbeazer.com/using-appsync-client-from-lambda/
import { env } from "process";
import { Config, env as Env } from "../../../../shared";
// This is such a bad practice
import AWS from "aws-sdk";
import { AWSAppSyncClient } from "aws-appsync";
import { Mutation, mutations } from "./mutations/";
// Very important, otherwise it won't work!!! You'll have Invariant Violation
// from Apollo Client.
import "cross-fetch/polyfill";
/**
*
*/
AWS.config.update({
region: Config.region,
credentials: new AWS.Credentials(
env.AWS_ACCESS_KEY_ID!,
env.AWS_SECRET_ACCESS_KEY!,
env.AWS_SESSION_TOKEN!
),
});
export class AppSyncClient {
client: AWSAppSyncClient<any>;
constructor() {
// Your AppSync endpoint - The Full URL.
if (!Env.APPSYNC_ENDPOINT) {
throw new Error("APPSYNC_ENDPOINT not defined");
}
/**
* We create the AppSyncClient with the AWS_IAM
* authentication.
*/
this.client = new AWSAppSyncClient({
url: Env.APPSYNC_ENDPOINT,
region: Config.region,
auth: {
credentials: AWS.config.credentials!,
type: "AWS_IAM",
},
disableOffline: true,
});
}
/**
* Sends a mutation on the AppSync Client
* #param mutate The Mutation that will be sent with the variables.
* #returns
*/
// The mutation is a object that holds the mutation in
// the `gql` tag. You can ommit this part.
sendMutation(mutate: Mutation) {
const mutation = mutations[mutate.type] as any;
const variables = mutate.variables;
// This is the important part.
return this.client.mutate({
mutation,
// Specify "no-cache" in the policy.
// network-only won't work.
fetchPolicy: "no-cache",
variables,
});
}
}
We need to enable IAM in the AppSync authorization mechanism. Yes, it is possible to have multiple Authentication enabled. I'm currently using OPEN_ID and IAM simultaneously.
https://us-east-2.console.aws.amazon.com/appsync/home?region=us-east-2#/myappsync-id/v1/settings
Here's the Lambda's IAM policy that executes the GQL:
{
"Statement": [
{
"Action": [
"appsync:GraphQL"
],
"Effect": "Allow",
"Resource": [
"arn:aws:appsync:us-east-2:747936726382:apis/ogolfgja65edlmhkcpp3lcmwli/*"
]
}
],
"Version": "2012-10-17"
}
You can further restrict here in the following fashion:
arn:${Partition}:appsync:${Region}:${Account}:apis/${GraphQLAPIId}/types/${TypeName}/fields/${FieldName}
arn:aws:appsync:us-east-2:747936726382:apis/ogolfgja65edlmhkcpp3lcmwli/types/Mutation/field/myCustomField"
Note, we need to better restrict this as we are currently giving it entire access to the API.
In your .gql file (AppSync GraphQL schema), add the #aws_iam directive to the mutation that is being used to send the subscriptions to, in order to restrict access from the front-end.
type Mutation {
addUsersMutationSubscription(
input: AddUsersSagaResultInput!
): AddUsersSagaResult #aws_iam
}
I'm new to AWS and still figuring out how to do things.
Part of my web application is using AWS S3 for file storage, but I want each user to be only able to access specific folders(for CRUD) in the bucket.
The backend server will track what folders the user will be able to access.
I know it is possible to define policies that allow access to specific folders(by matching prefix of objects), but can I generate these policies dynamically and get credentials with these policies attached (probably with Cognito?). So that these credentials could be passed to client-side to enable access to S3 folders.
I'm wondering if it is possible to do that and what services are required to achieve this.
You should change your view, each time you want to share a file with one of your users, you should check your database about their permissions( folders they have access) and if logical things on your side are correct, generate a presigned URL for access to that object.
How presigned URL works.
When you generate a presigned URL for accessing to an object, you can set the time limit too, it means after that time, the URL not work and expired.
For more information about the presigned URL, read the following documents on Amazon Web services website:
Generate a Pre-signed Object URL Using the AWS SDK for Java
Generate a Pre-signed Object URL Using AWS SDK for .NET
Also, if you want to create users and assign the right policy for access them to their folder you can follow these instructions:
You can use the IAM API to creating a user for each of your users, and attach the right policy for each of them.
For example, for creating the new user, you should use the following API
/* The following create-user command creates an IAM user named Bob in the current account. */
var params = {
UserName: "Bob"
};
iam.createUser(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
/*
data = {
User: {
Arn: "arn:aws:iam::123456789012:user/Bob",
CreateDate: <Date Representation>,
Path: "/",
UserId: "AKIAIOSFODNN7EXAMPLE",
UserName: "Bob"
}
}
*/
});
For more info about the Create user API, read the following
https://docs.aws.amazon.com/IAM/latest/APIReference/API_CreateUser.html
After creating a user, you should create a policy for each of them with CreatePolicy API.
var params = {
PolicyDocument: 'STRING_VALUE', /* required */
PolicyName: 'STRING_VALUE', /* required */
Description: 'STRING_VALUE',
Path: 'STRING_VALUE'
};
iam.createPolicy(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});
For more info about the Create policy read the following doc:
https://docs.aws.amazon.com/IAM/latest/APIReference/API_CreatePolicy.html
And finally, you should assign the policy you created before to each user by the AttachUserPolicy API.
/* The following command attaches the AWS managed policy named AdministratorAccess to the IAM user named Alice. */
var params = {
PolicyArn: "arn:aws:iam::aws:policy/AdministratorAccess",
UserName: "Alice"
};
iam.attachUserPolicy(params, function(err, data) {
if (err) console.log(err, err.stack); // an error occurred
else console.log(data); // successful response
});
For more info about the AttachUserPolicy API read the following doc:
https://docs.aws.amazon.com/IAM/latest/APIReference/API_AttachUserPolicy.html
The last part is about the which policy you should create and assign to each of them; we use the following policy for listing objects in each folder:
{
"Sid": "AllowListingOfUserFolder",
"Action": ["s3:ListBucket"],
"Effect": "Allow",
"Resource": ["arn:aws:s3:::my-company"],
"Condition":{"StringLike":{"s3:prefix":["home/David/*"]}}
}
And the following policy for actions in each folder:
{
"Sid": "AllowAllS3ActionsInUserFolder",
"Effect": "Allow",
"Action": ["s3:*"],
"Resource": ["arn:aws:s3:::my-company/home/David/*"]
}
For more detailed info about that policies read the following article by Jim Scharf:
https://aws.amazon.com/blogs/security/writing-iam-policies-grant-access-to-user-specific-folders-in-an-amazon-s3-bucket/
I'm getting GraphQLError: Request failed with status code 401
I followed the automatic configuration instructions from:
https://aws.github.io/aws-amplify/media/api_guide#automated-configuration-with-cli
I tried looking, but there are a lack of resources for IAM. It looks like everything should be setup automatically, and done with the Amplify CLI after I put in the IAM access key and secret.
Is further setup required? Here is my code:
import Amplify, { API, graphqlOperation, Hub } from "aws-amplify";
import aws_config from "../../aws-exports";
Amplify.configure(aws_config);
const ListKeywords = `query ListKeywords {
listKeyword {
keyword {
id
name
}
}
}`;
const loop = async () => {
const allKeywords = await API.graphql(graphqlOperation(ListKeywords));
}
Could it also be because my GraphQL resolvers are not setup yet for ListKeywords?
If you're using IAM as the Authorization type on your AppSync API then the issue is the Cognito Role being used with the Auth category when invoking Amplify.configure() isn't granted permissions for GraphQL operations. It needs something like this attached:
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"appsync:GraphQL"
],
"Resource": [
"arn:aws:appsync:us-west-2:123456789012:apis/YourGraphQLApiId/*"
]
}
]
}
More details here: https://docs.aws.amazon.com/appsync/latest/devguide/security.html
Not sure if this helps but I've been struggling with this for a while and found that if I add the API and use IAM as the auth method I need to add 'auth' to the schema too.
See below:
type TimeLapseCamera #model
#auth(rules: [
{ allow: private, provider: iam }
])
{
...
}
I just tested this and my web page is successfully adding a record.
Note to other comment; I do not have AWS at all in this - its a simple VUE app with Amplify.
I just changed ~/.aws/credentials and now it's working.
Looks like even if you have project specific configuration via Amplify's command line tools or ~/.awsmobile/aws-config.js, it still relies on ~/.aws
How can I get the identity id of the user (logged in by AWS Cognito) that invoked an AWS Lambda function? Do I have to use the SDK on the Lambda function to get the identity id?
In AWS javascript SDK inside lambda function just use
context.identity.cognitoIdentityId
It is working for me
If anyone else stumbles upon this, I think this will help you a lot.
Note this only applies if you're using the Cognito User Pool Authorizer. If you want to use AWS_IAM with Cognito Identitys check out my github example https://github.com/VictorioBerra/js-cognito-auth-example (read down to EDIT area below)
If you have "Use Lambda Proxy Integration" checked then you wont have access to Request Template Mappings. But you can get to the claims inside the token in your lambda function:
exports.handler = (event, context, callback) => {
//create a response
const response = {
statusCode: 200,
body: JSON.stringify({
"user email": event.requestContext.authorizer.claims.email,
}),
};
callback(null, response);
};
EDIT - More information for using AWS_IAM as APIG authorizer
Basically you need to have your APIG secured with AWS_IAM AND you must auth via a Cognito Federated Identity which will return a sessionToken example using user pools. This is what makes the AWS IAM credentials temporary. Now you have everything you need to auth to your APIG.
To test this, download the desktop version of postman, toss in your API URI (grab this from the stages area) and then under Authorization fill out the 5 fields you need for Sig4 signing. You will see 'event.identity' object in your lambda function is loaded up with properties such as the user object.
If you want to use the APIG auto-generated SDK it comes built in with a factory that takes the accessKey, secret, and token and signs everything for you. Same with the aws-sdk. You can init the credentials with those three items and it will automatically sign all requests for you with those temp creds. If you want to straight up manually hit your API with window.fetch, request, curl, (insert http client here) you can calculate your own Sig4 (beware it can be a little complicated or use a modern library to do it for you.
Also for the record, while doing my research I noticed that if you want to NOT use AWS_IAM as an APIG authorizer, and you want to use "Cognito Identity Pool Authorizer" which is a fancy new option in the dropdown in APIG you can still get a ton of info on the user in the lambda event if you just pass the JWT gained from a successful Cognito popl auth to the APIG as the Authorization header. Inside that JWT is a lot of attributes which you can customize in your pool settings.
IMO professional opinion I think using the AWS_IAM temp creds authorizer is preferred. This way, you can use as many different IdPs as you want in Cognito Identities (Facebook, Twitter, pools, etc.)
If you go through API Gateway, you can pass the cognito id (as well as the user arn and other useful information) to Lambda. This solved the issue for me.
http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-mapping-template-reference.html
Per the docs, it looks like information about the identity provider would only be available for an invoke through the Mobile SDK.
To get around this, one option is to pass the identity ID to the function manually as part of the event. Assuming you are doing something like AWS.config.credentials = new AWS.CognitoIdentityCredentials(...) then you should be able to get the ID via AWS.config.credentials.identityId (after the credentials are refreshed).
EDIT: A better option for identity validation is to let Cognito/IAM handle it, and assume that if a user can successfully invoke a Lambda function, that means they are allowed to. In this case to manage per-user validation, take a look at whitelisting.
For anyone else still struggling to obtain the IdentityId of a Cognito User in a Lambda Function, after many hours of exploration, I discovered that the IdentityId can be obtained within a Lambda Function in the following ways depending on the method you use to invoke the Lambda Function:
Invocation via an API-Gateway trigger with a Cognito User Pool Authorizer
The IdentityId can be obtained in the following way:
const IDENTITY_POOL_ID = "us-west-2:7y812k8a-1w26-8dk4-84iw-2kdi849sku72"
const USER_POOL_ID = "cognito-idp.us-west-2.amazonaws.com/us-west-2_an976DxVk"
const { CognitoIdentityClient } = require("#aws-sdk/client-cognito-identity");
const { fromCognitoIdentityPool } = require("#aws-sdk/credential-provider-cognito-identity");
exports.handler = async (event,context) => {
const cognitoidentity = new CognitoIdentityClient({
credentials: fromCognitoIdentityPool({
client: new CognitoIdentityClient(),
identityPoolId: IDENTITY_POOL_ID,
logins: {
[USER_POOL_ID]:event.headers.Authorization
}
}),
});
var credentials = await cognitoidentity.config.credentials()
console.log(credentials)
// {
// identityId: 'us-west-2:d393294b-ff23-43t6-d8s5-59876321457d',
// accessKeyId: 'ALALA2RZ7KTS7STD3VXLM',
// secretAccessKey: '/AldkSdt67saAddb6vddRIrs32adQCAo99XM6',
// sessionToken: 'IQoJb3JpZ2luX2VjEJj//////////...', // sessionToken cut for brevity
// expiration: 2022-07-17T08:58:10.000Z
// }
var identity_ID = credentials.identityId
console.log(identity_ID)
// us-west-2:d393294b-ff23-43t6-d8s5-59876321457d
const response = {
statusCode: 200,
headers: {
"Access-Control-Allow-Headers": "*",
"Access-Control-Allow-Origin": "*",
"Access-Control-Allow-Methods" : "OPTIONS,POST,GET,PUT"
},
body:JSON.stringify(identity_ID)
};
return response;
}
Why?
Invoking a Lambda Function using an API-Gateway trigger with a Cognito User Pool Authorizer will result in the following fields (among additional fields which have been removed for brevity) being available in the event of the invocation:
{
"resource": "/{proxy+}",
"path": "/_",
"httpMethod": "POST",
"headers": {
"Authorization": "eyJrmlaod8(kyC9zdspo0jZIYjRENFlCNVBidnksl89DNm9USDJrT25MSDhjXC9EYkIzMzQ8389iYWxnIjoiUlMyNTYifQ.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.hk-8ajGP2jO0RQvzwZWp2d5T1BLiWL9q6vvrbXemLBbd2kb1kkBSvklfC_7WWvJoy1ukwNoq8Cx63U2hQfjJB077AHrHfN2PkJu4DG86vSdtSzrZVDQmle331UxopLQvzDZ1mejfmSFbo6x1ZeTbo39PRpox4pzsfeUAM1Rf8H6y8OrdPZa7Gh6gRkiN2IcwdBnXI4-Q6HX5QqiVzr2O4zEnNsqMFfsFA3aO05hnp7EYRWHgS6EgaQjfBirCoyerBkjFJTXynl76Jj4fK3-3KY4tw5EHplxkgAih7a9QTxy8SbRee8kh7fwrIGEO6CtgkM9v0XL7jBPtNtGTpqBRzw"
},
"requestContext": {
"authorizer": {
"claims": {
"sub": "231df9d7-0aab-4dsd-8389-d315d9daca7f",
"email_verified": "true",
"iss": "https://cognito-idp.us-west-2.amazonaws.com/us-west-2_an976DxVk",
"custom:first_key": "false",
"cognito:username": "231df9d7-0aab-4dsd-8389-d315d9daca7f",
"origin_jti": "8131rlpo-5123-436b-b199-41315d9d4487",
"aud": "r6315d9dt9sdls315d9d5h3cn",
"event_id": "f3dsp9d8-213e-4648-8f80-f8315d9dc84e",
"custom:name": "my_name",
"token_use": "id",
"auth_time": "1658148859",
"exp": "Mon Jul 18 09:23:17 UTC 2022",
"iat": "Mon Jul 18 08:23:17 UTC 2022",
"jti": "982sdafe-97rs-996l-i899-k315d9d09n7n",
"email": "jeff#amazon.com"
}
},
"extendedRequestId": "dSiT_dLdJdad9oP=",
"requestTime": "18/Jul/2022:08:23:27 +0000",
"requestTimeEpoch": 1658132607750,
"requestId": "387ss00s3-add0-62i9-l9s0-9a8dj8976dfa",
"identity": {
"cognitoIdentityPoolId": null,
"accountId": null,
"cognitoIdentityId": null,
"caller": null,
"sourceIp": "91.83.769.200",
"principalOrgId": null,
"accessKey": null,
"cognitoAuthenticationType": null,
"cognitoAuthenticationProvider": null,
"userArn": null,
"userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0",
"user": null
},
"domainName": "mskd8fpni2.execute-api.us-west-2.amazonaws.com",
"apiId": "mskds98ni2"
},
"body": "{\"name\":\"my_name\"}",
"isBase64Encoded": false
}
and the following fields being available in the context of the invocation:
{
"callbackWaitsForEmptyEventLoop": true,
"functionVersion": "$LATEST",
"functionName": "hello-world-jsHelloWorldFunction-kTdLswTRrkdS",
"memoryLimitInMB": "512",
"logGroupName": "/aws/lambda/hello-world-jsHelloWorldFunction-kTdLswTRrkdS",
"logStreamName": "2022/07/15/[$LATEST]95edi84719944bdi84a6cdi8451di849",
"invokedFunctionArn": "arn:aws:lambda:us-west-2:598763214571:function:hello-world-jsHelloWorldFunction-kTdLswTRrkdS",
"awsRequestId": "d8s57juq-3g39-49sk-8625-5849sk9be44I"
}
Notice the following things:
The Cognito User's IdentityId is not available in either the event or the context
Other information about the Cognito User is available in the event (email, sub, custom attributes, etc.)
The request invocation time is available in the event (the time that the lambda function was invoked which is available in event.requestContext.requestTime and event.requestContext.requestTimeEpoch)
Note: Please leave a comment if you are having a hard time setting up an API-Gateway trigger with a Cognito User Pool Authorizer for your Lambda Function, if people are interested I will add instructions on how to accomplish this.
Direct invocation using a Cognito User's credentials and the AWS SDK for JavaScript v3
The IdentityId can be obtained in the following way:
exports.handler = async (event,context) => {
var identity_ID = context.identity.cognitoIdentityId
console.log(identity_ID)
// us-west-2:d393294b-ff23-43t6-d8s5-59876321457d
const response = {
statusCode: 200,
headers: {
"Access-Control-Allow-Headers": "*",
"Access-Control-Allow-Origin": "*",
"Access-Control-Allow-Methods" : "OPTIONS,POST,GET,PUT"
},
body:JSON.stringify(identity_ID)
};
return response;
}
Why?
Directly invoking a Lambda Function using the AWS SDK for Javascript v3 and a Cognito User's credentials will result in no additional information being available in the event of the invocation:
{
"name": "my_name"
}
however, the IdentityId is available in the context of the invocation:
{
"callbackWaitsForEmptyEventLoop": true,
"functionVersion": "$LATEST",
"functionName": "hello-world-jsHelloWorldFunction-kTdLswTRrkdS",
"memoryLimitInMB": "512",
"logGroupName": "/aws/lambda/hello-world-jsHelloWorldFunction-kTdLswTRrkdS",
"logStreamName": "2022/07/15/[$LATEST]95edi84719944bdi84a6cdi8451di849",
"identity": {
"cognitoIdentityId": "us-west-2:d393294b-ff23-43t6-d8s5-59876321457d",
"cognitoIdentityPoolId": "us-west-2:7y812k8a-1w26-8dk4-84iw-2kdi849sku72"
},
"invokedFunctionArn": "arn:aws:lambda:us-west-2:598763214571:function:hello-world-jsHelloWorldFunction-kTdLswTRrkdS",
"awsRequestId": "d8s57juq-3g39-49sk-8625-5849sk9be44I"
}
Notice the following things:
The Cognito User's IdentityId is available in context.identity.cognitoIdentityId
Additional information about the Cognito User is not available in the event or the context (email, sub, custom attributes, etc.)
The request invocation time is not available in either the event or context
Note: To directly invoke a Lambda Function using a Cognito User's credentials and the AWS SDK for JavaScript v3, you need to add a custom IAM Permission to the IAM Role assumed by authenticated Users in your Cognito User Pool. To do this:
Go to IAM -> Roles, and find the role for your user pool such as amplify-myapp-prod-12987-authRole
Click "Add permissions"
Click "Create inline policy"
Click "JSON"
Insert the following policy and replace the Function ARN with the ARN of your Lambda Function:
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "VisualEditor0",
"Effect": "Allow",
"Action": [
"lambda:InvokeFunctionUrl",
"lambda:InvokeFunction"
],
"Resource": [
"arn:aws:lambda:*:598763214571:function:hello-world-jsHelloWorldFunction-kTdLswTRrkdS"
]
}
]
}
Click "Review Policy"
Save the policy
Invocation methods that don't currently support authenticating users from a Cognito User Pool:
Invoking with caller credentials (this only works if you are using AWS_IAM authentication, not a Cognito User Pool Authorizer)
Invoking via a function URL (this only supports AWS_IAM authentication as well)
My observation is the following.
If you call the API Gateway with a signed Request where you actually provide the accesskey, secret and sessionToken which you can extract via (JS SDK):
AWS.config.credentials = new AWS.CognitoIdentityCredentials(...)
AWS.config.credentials.get(..)
And assumed that your lambda is called from API-Gateway via LAMBDA_PROXY and Authorizer AWS_IAM. You can only access user stuff in lambda with:
exports.create = function (event, context) {
secdata = event.requestContext.identity.cognitoAuthenticationProvider;
}
Then you will get, apart from other stuff, the "sub" of the cognito UserPool User. So if you really want to know more about the user, it seems you need to ask AWS again via SDK call.
For a Python Lambda, invoked via Javascript AWS SDK / Cognito / Amplify...
https://docs.aws.amazon.com/lambda/latest/dg/python-context-object.html
context.identity.cognito_identity_id
It should look something like this:
{aws region}:{ GUID }
Assuming you are using an Identity Pool, this will return the Cognito Federated Identity, that can be used for fine grained access control. This is safer than relying on the Javascript payload containing the identity id.
The Cognito Identity Pool Auth Role will need to have Lambda:InvokeFunction policy, otherwise the user won't be able to invoke the function in the first place.
Edit: This works when calling the Lambda function DIRECTLY, not via API Gateway.
Edit2: The Cognito user is allowed to call the lambda because it is explicitly set in the IAM Cognito Auth role.
I was using Kotlin and my Lambda handler was
override fun handleRequest(event: APIGatewayProxyRequestEvent, context: Context): APIGatewayProxyResponseEvent
But event.requestContext had no authorizer. The solution was to upgrade the dependency in build.gradle from
com.amazonaws:aws-lambda-java-events:2.1.0 to com.amazonaws:aws-lambda-java-events:2.2.7. After that, I got the username as follows.
val claims = requestContext.authorizer["claims"] as Map<String, String>
println(claims["cognito:username"])
println(claims["email"])