Custom Cache-control headers

[nj]

The header currently sent by Surfer for all requests is Cache-Control: public, max-age=0

This setting causes the browsers to re-request everything that could have been cached instead. If the max-age value could be customizable from settings or somehow else, that would be a lot less strain on the Surfer on Cloudron.

My use-case:
I run Surfer behind Cloudflare, and Cloudflare honors the cache settings, but only if max-age is set to a non-zero value. Basically Cloudflare is not caching anything and my Surfer instance is constantly running out of memory because of the number of requests.

[nj]

@staff
Tagging for visibility of the post.

[nebulon]

I think that makes sense, currently it uses the express.static() defaults only.

[marcusquinn]

Even a setting of a few seconds is useful

[nebulon]

So surfer already sets the ETag https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ETag but no max-age The max-age setting basically makes the browser not even check in the with server if the content may have changed.

Now various frameworks set the max-age very high and use other cash busting techinques (like changing the file path hash) to serve up-to-date content if needed.

For surfer this is hard to implement, as the main html pages have to be aware of this. So I am not sure how surfer can set max-age and ensure that content is fresh at the same time.

[nebulon]

Given that this is CloudFlare acting as a browser here, I wonder if they have cache settings on their own to for example mark a subpath of the proxied app as valid for n seconds?

[girish]

In theory , max-age=0 means the same as no-cache . no-cache means cache it but always revalidate. It seems max-age=0 allows stale reuse and thus there is also a must-revalidate to prevent that.

Cloudflare has it's own interpretation. Per https://developers.cloudflare.com/cache/about/default-cache-behavior , it won't cache at all with max-age=0. We have to create a custom page rule - https://developers.cloudflare.com/cache/how-to/create-page-rules/ to override the default caching behavior.

So... my interpreation is that we need Cache-Control: public, max-age=1, must-revalidate if we want this to work out of the box in Cloudflare.

[girish]

https://learn.microsoft.com/en-us/azure/cdn/cdn-how-caching-works is an excellent read on some other interpretations.