Use multiple same header field in Lambda Proxy Integration

Question

I'm writing a Lambda function that returns a response for Lambda Proxy Integration in Python. The API expects headers to be a dictionary.

{
    "isBase64Encoded": true|false,
    "statusCode": httpStatusCode,
    "headers": { "headerName": "headerValue", ... },
    "body": "..."
}

This requires each header field to be unique, so there is no way to use multiple Set-Cookie's. I've already tried to convert the dictionary to a list of tuples

{
    "isBase64Encoded": true|false,
    "statusCode": httpStatusCode,
    "headers": [ ("headerName": "headerValue"), ... ],
    "body": "..."
}

but API gateway complains Malformed Lambda proxy response.

Any idea how to set headers with the same name?

Answer 1

It is currently not possible to send multiple cookies with lambda integration.

If you send multiple set-cookie, then it will take the last one. ok, such a junk implementation right.

Reference, How can I send multiple Set-Cookie headers from API Gateway using a proxied Lambda

Let us see other avaialable options,

Lambda@Edge:

Here is what I find working with Lambda@Edge,

You can create a lambda function for viewer response and modify the header to set cookies.

'use strict';

exports.handler = (event, context, callback) => {
   const response = event.Records[0].cf.response;
   const headers = response.headers;

   // send via a single header and split it into multiple set cookie here.
   headers['set-Cookie'] = 'cookie1';
   headers['Set-Cookie'] = 'cookie2';

   callback(null, response);
};

API Gateway Integration Request mapping:

Here is what I found and got working with integration request,

Hope it helps.