How to setup caching for specific headers in Firebase Cloud Functions?

Question

I'm unsure if this is even possible. I'm making requests to an external api and on each request from my app I pass the user's query into a custom 'query' header in the Cloud Function (Typescript). ⤵

export const searchQuery = functions.https.onRequest(async (request, response) => {

    // : Reads request query data from user
    const query = request.headers.query;

...

I attempted to setup caching so that with each query it caches the result separately but it doesn't seem to be working. ~

( caching does work without vary header set however it's only caching the first search result )
( all requests are sent as GET )

This is the block that sets the 'query' header as a vary rule for caching (written in Typescript). ⤵

...

    return await admin.auth().verifyIdToken(tokenId) // : Authenticates response
        .then(() => {

            // : Set cache-control
            console.log(request.headers);
            response.set('Vary', 'Accept-Encoding, query');
            response.set("Cache-Control", "public, s-maxage=600");
            response.set("Access-Control-Allow-Origin", "*");
            response.set("Access-Control-Allow-Methods", "GET");

            // : Grab API search data
            axio.get(urlAssembler).then(APIData => {
                response.status(200).send(APIData.data);
            }).catch(error => console.log(error));

        })
        .catch((err) => response.status(401).send(err));

...

I have this setup on Cloud Functions w/ Firebase and not Cloud Functions with Firebase Hosting. I'm wondering if maybe there's a difference there but it seems there isn't.

In my firebase.json I noticed that it is setup for Cloud Functions and not for Firebase Hosting. Perhaps I need to set it up as Firebase Hosting to define cache-control for headers there?

This is my firebase.json ⤵

{
  "functions": {
    "predeploy": [
      "npm --prefix \"$RESOURCE_DIR\" run lint",
      "npm --prefix \"$RESOURCE_DIR\" run build"
    ]
  }
}

Answer 1

I contacted Firebase support regarding this and the individual helping me said that Firebase Hosting needs to be used in order to cache based on a header like described above.

I have not tested this yet so once I test it I will update this answer to confirm that it works.

There is an article suggested to me by the individual helping me from Firebase support for how to cache within a Cloud Function but I don't believe this makes use of a CDN.