Won't it be possible to server stale content from proxy-cache plugin anyway?

[khaled4vokalz]

The DOC (https://docs.konghq.com/hub/kong-inc/proxy-cache/#upstream-outages) states that the proxy-cache can't serve stale content currently

Due to an implementation in Kong’s core request processing model

So, is there any plan on mitigating this? or is it possible to do it on our own? Or there's no way, as the core doesn't support it...

[StarlightIbuki]

What the document says is that when the upstream is out, and all the local caches are out of life, it cannot serve any content.
The following sentence suggests setting a larger storage_ttl to make the cache persist longer. Note that the cache lifetime is different from what we usually refer to as HTTP cache lifetime.

[khaled4vokalz]

@StarlightIbuki ,
I was more talking about features like this e.g. https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_cache_background_update .... setting a large storage_ttl and large cache_control header doesn't always make sense right? It'd have been nice if we could handle contents that gets updated in short time spans.... Currently It's not possible from KONG to tackle highloads on upstreams on a stale cache scenario, but nginx provides that out of the box....

[StarlightIbuki]

I got your point. However, the only possible solution I can think of would be to always keep a version in memory and that's almost the same as a long ttl.
If you've got a better idea please raise a feature request ticket.

[khaled4vokalz]

It seems like it is possible to server STALE content from the plugin, adding background_update support requires a feature request I guess. I'll see if I get the time to propose something as a feature request. Closing this discussion for now.