Get response headers from subgraph services in Apollo router

I am currently running a federation service and in the process of migrating to Apollo-router. Currently, I am stuck on getting response headers in the execution_service stage. My Authentication-service handles user login and on successful login I set a response header with the key token and the value is the corresponding JWT. I want to be able to get this header in my Apollo router and then subsequently store that in a cookie on the browser and then send that cookie (by converting it to a header) and passing it to subgraphs on subsequent requests.

How do I go about this?

You should be able to have the headers coming into the Apollo Router propagate to downstream services (docs). This could be used to forward the cookie header to downstream subgraphs.