I am trying to set up an API Gateway to call another lambda function that will upload an image to S3. The feature works well when I am using an app like POSTMAN, however when I run the browser using React I am getting the following error.
Access to fetch at 'https://.../upload' from origin 'http://localhost:3000' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
In my API Gateway I have the following configuration for that method
Gateway Responses for UserUpload API: default 4XX (not checked), default 5XX (not checked)
Methods: post (checked), options (checked)
Access-Control-Allow-Methods: options, post
Access-Control-Allow-Headers: '*'
Access-Control-Allow-Origin: '*'
This API uses an authorizer, I am using the one provided by Auth0 and have not edited the code at all.
And the function that my authorizer calls returns the response like the below (eg happy path):
exports.handler = async (event) => {
//do data checks and upload to s3
return {
headers: {
"Content-Type": "application/json",
"Access-Control-Allow-Methods": "*",
"Access-Control-Allow-Origin": "*",
},
statusCode: 200,
body: JSON.stringify({ message: "success" }),
};
This is my first time setting up both a lambda function, authorisation provider and API Gateway so I might be missing something obvious. I have also tried added mode: no-cors to my fetch POST requests however they still fail in a very similar way.
From what I can tell by looking at the logs of the authorizer and the lambda function that uploads the images, is that they are not even being called. So it appears the CORS error is with the API Gateway.
I have seen in a few tutorials that in their aws template yaml files they add an option AddDefaultAuthorizerToCorsPreflight as False. I can't see this anywhere in the API Gateway console.
Update: I have tested my function with the custom authoriser turned off and it works. So I know that CORS works for the options method, and for the returned request on the lambda function. It is the custom authoriser that is the problem.
The flow is currently:
Method Request - Auth: my-auth-0-authorizer
Integration Request - Type: Lambda_proxy
Lambda function
Integration response - [greyed out Proxy integrations cannot be configured to transform responses]
Method Response: HTTP Status: Proxy (with Access-Control-Allow-Origin in the response headers)
What do I have to do differently or change to allow my authoriser to respect the CORS config?
Update: After leaving my API Gateway for a day, successful responses are now working (using the flow mentioned above). I am not sure if there was a glitch in the system or there was unexpected occurring but it is now working. I am still getting a CORS issue but now only with bad responses.
The custom authoriser fails by return context.fail("Unauthorized"); and when this occurs my browser gets a CORS error. Do I have to set up special gateway responses for 4XX responses?
Related
Am getting the following error:
Access to fetch at 'https://...' from origin 'https://...' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
p.s. from blazor wasm web api call
Enabling CORS support for Lambda or HTTP non-proxy integrations and AWS service integrations
For a Lambda custom (non-proxy) integration, HTTP custom (non-proxy) integration, or AWS service integration, you can set up the required headers by using API Gateway method response and integration response settings. When you enable CORS by using the AWS Management Console, API Gateway creates an OPTIONS method and attempts to add the Access-Control-Allow-Origin header to your existing method integration responses.
This doesn’t always work, and sometimes you need to manually modify the integration response to properly enable CORS. Usually this just means manually modifying the integration response to return the Access-Control-Allow-Origin header.
exports.handler = async (event) => {
const response = {
statusCode: 200,
headers: {
"Access-Control-Allow-Headers" : "Content-Type",
"Access-Control-Allow-Origin": "https://www.example.com",
"Access-Control-Allow-Methods": "OPTIONS,POST,GET"
},
body: JSON.stringify('Hello from Lambda!'),
};
return response;
};
Have you tried the following?
make sure to set
Access-Control-Allow-Origin
*
Access-Control-Allow-Headers
*
Access-Control-Allow-Methods
*
p.s.
you may need to make the above more restrictive e.g. to your apps domain
also don't forget to clear your browsers cache
https://console.aws.amazon.com/apigateway/main/develop/cors
I have been struggling with setting up AWS API Gateway to pass Query string parameters to my Lambda function.
If I set to API to use Lambda proxy integration, I get a CORS error at the Web client
[index.html:1 Access to XMLHttpRequest at 'https://g2kza1o79f.execute-api.eu-west-2.amazonaws.com/prod/gettest8' from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.]
( - even when I have set the API with CORS enabled.
If I set the API to not use Lambda proxy integration, and CORS enabled, the API call works (no CORS error), but the event object received in my Lambda function is empty( hence no query string parameters).
In both cases I am using the GET method.
I can see in the Method Response Header the Access-Control-Allow-Origin option is present, but cannot access the Integration Response
Question: How can I set-up my API to pass query string parameters through to my Lambda function without getting the CORS error? I will also be wanting to set up APIs for POST requests to other Lambda functions.
I believe it is related to First Enable CORS Then Deploy API.
A good thread could be found here.
API Gateway CORS: no 'Access-Control-Allow-Origin' header
I can't Enable CORS on my API Gateway instance, this is how it looks:
1. Settings:
2. Result:
I've tried a bunch of things like checking the DEFAULT 4XX and DEFAULT 5XX and manually inputting the Access-Control-Allow-Methods as suggested in some posts.
If I hover over the error I get: Invalid Response status code specified.
I'm able to GET using my browser but POST can only be done from Postman. My ReactJS website won't post either, throwing:
Access to XMLHttpRequest at <ENDPOINT> from origin <S3-REACT-BUCKET> has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
I've read that I have my React app should send the CORS headers (haven't got to that) but I can't even Enable CORS in the API Gateway!
That was because No Method Response
You shouldn't manually go on the console to enable CORS. Instead follow this guide from the serverless framework.
In short:
set cors: true in your http event
return {'Access-Control-Allow-Origin': '*','Access-Control-Allow-Credentials': true} in your handler
I am using serverless to deploy my service. This is how i am configuring a lambda function
hello:
handler: handler.hello
events:
- http:
path: /hello
method: get
cors: true
authorizer: aws_iam
Also i am using AWS cognito to authorise logged in user. The same user credentials are working for other serverless services but for this one. we are sending proper response headers as well as mentioned in some other solutions. I have tried almost everything i could find.
This is the error i am getting (Though option call is giving 200).
Access to fetch at 'https://*******.execute-api.us-east-2.amazonaws.com/dev/hello' from origin 'http://***.ngrok.io' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
I would appreciate your help.
Please comment if any other information is required for you to understand my problem.
Thanks a lot.
you should return access-control-allow-Origin from lambda resposne as well.
In python it is something like this
return {'statusCode': status_code,
'body': response,
'isBase64Encoded': False,
'headers':{ 'Access-Control-Allow-Origin': 'http://localhost:3000'}}
more about it here
I have a AWS Lambda function that is triggered via AWS API Gateway. When I test my function on Lambda it is working. When I send a POST request to the API url via ajax, I get a 502 bad gateway error.
XMLHttpRequest cannot load https://xxxxxxxx.execute-api.us-east-1.amazonaws.com/prod/myLambdaFunction. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'mywebsite.com' is therefore not allowed access. The response had HTTP status code 502.
Obviously this was a CORS issue, so I thought I could change the CORS settings in my AWS API Gateway URL which I did, but I am still getting an error for this.
What do I have to change on AWS side or my own to be able to POST to the URL?
Unfortunately there is a known issue with many classes of 4xx and 5xx errors where CORS headers will not be sent, even if you've added CORS support via the console.
As noted in comments, the CORS error is a side effect of the fact that your API is returning a 502. This often occurs if you are using the LAMBDA_PROXY integration type and are returning invalid JSON from your Lambda function.
Please try either using the test invoke functionality from the console or enable logging in your API to debug further.
I solved that exact same problem by outputting the CORS header myself.
See below - and I hope that'll help.
Teebo
Amazon docs
function respond(context, responseData) {
var response = {
statusCode: 200,
body: JSON.stringify(responseData),
headers: {
"Content-Type": "application/json; charset=utf-8",
"Access-Control-Allow-Origin": "*"
}
};
context.succeed(response); }