Change Details

We've found that when the renderers emit a 404 (e.g. one with content like: `Error generating thumbnail The source file 'foo.jpg' does not exist.`), Swift seems to tack on a `Cache-Control: no-cache` header before emitting it to Varnish. This prevents Varnishes from caching the 404 at all, which means all such traffic cuts through all layers. Varnish already has generic code which limits all 4xx TTLs to 10 minutes if they're longer than that. In other such scenarios, we've considered 10 minute 404s to be an acceptable tradeoff (e.g. on creation of new resources) so that we don't spam the backend so hard if a 404 becomes popular. Is there a reason caching them is bad in the upload case?

We've found that when the renderers emit a 404 (e.g. one with content like: `Error generating thumbnail The source file 'foo.jpg' does not exist.`), they tack on a `Cache-Control: no-cache` header before emitting it to Varnish. This prevents Varnishes from caching the 404 at all, which means all such traffic cuts through all layers. Varnish already has generic code which limits all 4xx TTLs to 10 minutes if they're longer than that. In other such scenarios, we've considered 10 minute 404s to be an acceptable tradeoff (e.g. on creation of new resources) so that we don't spam the backend so hard if a 404 becomes popular. Is there a reason caching them is bad in the upload case?

We've found that when the renderers emit a 404 (e.g. one with content like: `Error generating thumbnail The source file 'foo.jpg' does not exist.`), Swift seems tothey tack on a `Cache-Control: no-cache` header before emitting it to Varnish. This prevents Varnishes from caching the 404 at all, which means all such traffic cuts through all layers. Varnish already has generic code which limits all 4xx TTLs to 10 minutes if they're longer than that. In other such scenarios, we've considered 10 minute 404s to be an acceptable tradeoff (e.g. on creation of new resources) so that we don't spam the backend so hard if a 404 becomes popular. Is there a reason caching them is bad in the upload case?