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/API Gateway as Reverse HTTP Proxy to SQS/

API Gateway as Reverse HTTP Proxy to SQS

0

I am trying to use AWS API Gateway as a reverse (forwarding) proxy to AWS SQS. I essentially want to send a REST request to the API Gateway which then gets forwarded directly to the SQS REST API and returns the response.

When I send a request to the gateway, I immediately get back

<?xml version="1.0"?>
  <ErrorResponse xmlns="http://queue.amazonaws.com/doc/2012-11-05/">
    <Error>
      <Type>Sender</Type>
      <Code>AccessDenied</Code>
      <Message>Access to the resource https://sqs.us-east-1.amazonaws.com/ is denied.</Message>
      <Detail/>
    </Error>
    <RequestId>51c903b2-4da3-5d5e-a3b8-589ee72167de</RequestId>
  </ErrorResponse>

However, when I switch the request URL to SQS directly (https://sqs.us-east-1.amazonaws.com) the request succeeds.

What am I missing?

curl --request POST 'https://my-api-gateway.com/sqs' \
--header 'X-Amz-Date: <date>' \
--header 'X-Amz-Security-Token: <token>' \
--header 'Authorization: <auth>' \
--header 'Amz-Sdk-Invocation-Id: <invocation>' \
--header 'Amz-Sdk-Request: attempt=1; max=10' \
--header 'User-Agent: aws-sdk-go-v2/1.16.5 os/macos lang/go/1.18.3 md/GOOS/darwin md/GOARCH/arm64 api/sqs/1.18.6' \
--header 'Content-Length: 206' \
--data-urlencode 'Action=ReceiveMessage' \
--data-urlencode 'MaxNumberOfMessages=10' \
--data-urlencode 'QueueUrl=<my-queue-url>' \
--data-urlencode 'Version=2012-11-05' \
--data-urlencode 'WaitTimeSeconds=20'

Configuration:

  1. Integrations
  2. Routes
  3. Parameter Mappings
2 Answers
1
Accepted Answer

In this case it is required to configure an IAM Role for API Gateway to assume with the required sqs:SendMessage permission as API Gateway will drop the Authorization header if it contains an AWS Signature. It's in the docs but well hidden under the header mapping table.

  • The Authorization header is dropped if it contains a Signature Version 4 signature.
answered 11 days ago
0

Did you create a role for API Gateway that has a policy that allows API Gateway to interact with the SQS queue?

answered 11 days ago
  • just curious but why would that be required? I am strictly using the REST API which is passing the authentication headers to SQS. The gateway itself shouldn't really know that it's calling SQS should it?

  • In this case the API Gateway receives the REST request but has to make an SQS API call behind the scenes, so it will need to be granted the access based on the principle of least privilege.

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