Setting Cookie in http response header from AWS lambda Node JS - node.js

Question

I have a Lambda proxy integration enabled, and setting the response headers as part of Lambda output and API Gateway that will return them as part of the HTTP response to the client.
Sample code:
callback(null, {
"statusCode": 302,
"Location" : "https://somewebsite.com"
"headers": { "headerName": "headerValue", ... },
"body": "..."
});
I need to send out 3 cookies in the headers. I tried. But, failed:
callback(null, {
"statusCode": 302,
"Location" : "https://somewebsite.com"
"headers": { "Set-Cookie": [cookie1String, cookie2String, cookie3String] },
"body": "..."
});
[Edit]
I concatenated the cookie and passed in as the response, the client gets the cookie. But when the client calls the target in "location", the request does not have the cookie in the header.
callback(null, {
"statusCode": 302,
"Location" : "https://somewebsite.com"
"headers": { "Set-Cookie": c1=cookie1String;c2=cookie2String; c3=cookie3String] },
"body": "..."
});
Please help in sending these 3 cookies out to my client.

Answer 1

Use multiValueHeaders instead of headers.
const response = {
isBase64Encoded: true,
statusCode: 200,
multiValueHeaders : {"Set-Cookie": [`language=${language}`, `theme=${theme}`]},
body: JSON.stringify('User profile set successfully')
};
callback(null, response);
If you need it to be smarter, consider something like
function createHeaders(headers) {
const defaultHeaders = {
'Access-Control-Allow-Origin': '*',
};
const allHeaders = Object.assign({}, defaultHeaders, headers);
const singleValueHeaders = {};
const multiValueHeaders = {};
Object.entries(allHeaders).forEach(([key, value]) => {
const targetHeaders = Array.isArray(value) ? multiValueHeaders : singleValueHeaders;
Object.assign(targetHeaders, { [key]: value });
});
return {
headers: singleValueHeaders,
multiValueHeaders,
};
}
Then use it in the callback function.
callback(null, {
statusCode: status || 200,
body: JSON.stringify(body),
...createHeaders({ 'Set-Cookie': cookie }),
});

Answer 2

API gateway does not let you map the same header more than once. I got around by using different casing to set-cookie method.
callback(null, {
"statusCode": 302,
"Location" : "https://somewebsite.com"
"headers": { "Set-Cookie": cookie1, "set-Cookie": cookie2 },
"body": "..."
});

Answer 3

I would say that your issue is related to the fact that your response object in the callback is not formatted the way the api gateway expects.
These links reference aws documentation specifically to that.
http://docs.aws.amazon.com/apigateway/latest/developerguide/handle-errors-in-lambda-integration.html
Issue with your code...
'location' does not look like a valid property
Make sure your header key/value pairs are actual JSON objects using something like JSON.stringify
Don't forget to enable logs for both api gateway and lambda with full requests and responses. These two logs will help you debug.