Firebase Storage – getting static link based on filename

Question

I have a situation where in Firebase Storage users store their avatar to /users/{uid}.jpg

If I then use the Storage API to get the download URL and display the image, it ends up being very slow to make the first request because the download URL is not cached anywhere.

So my solution is to get the DownloadURL when the user uploads the image and store that in Firebase allowing the client image provider to automatically cache the image which speeds up loads considerably.

However, there is one problem with this solution.

If a user replaces their avatar, the old link becomes broken instead of updated. I believe this is because a new token is generated each time something is uploaded for security reasons but these are of no benefit to me.

So my question is twofold:

1) How can I allow a user to upload an avatar to a path that is dedicated to them such as /users/{uid}.jpg, get a bare download URL that can be cached by the client, and have that URL remain the same even when the file changes at /users/{uid}.jpg

2) If this is not possible, what is the normal way to solve this issue?

Answer 1

Download URLs are opaque. The contents of the actual URL itself is an implementation detail of the system, and it's not supported to dig around in its contents. The URLs can't be dissected or composed.

You can use a storage trigger with Cloud Functions to automatically generate a signed URL whenever something changes in your storage bucket.

Answer 2

So instead of serving from a hard-coded URL, simply retrieve the URL from an updated value in the datastore (or any data storage system). Every time the user updates the avatar, simply store the new URL in the datastore and you can query for it when you need it.