I’m trying to understand our caching setup a bit better with Fastly<->S3, given bandwidth between S3 and fastly is our largest cost.

I noticed we’re not serving any Cache-Control headers on our NAR files, but I think we could set Cache-Control: immutable on all NAR objects in S3 as NAR files are content-addressed they should never change? Fastly respects these response headers to decide how long to cache things for.

Do I understand correctly that

https://github.com/NixOS/infra/blob/88f1c42e90ab88673ddde3bf973330fb2fcf23be/terraform/cache.tf#L138C17-L138C22

is the only thing configuring how long we hold things in cache? (seems to be 24 hours).

Given we also cache 404s on narinfos I guess that makes sense. (In case the narinfo gets uploaded later it invalidates it). But can’t we cache NARs way more aggressively than 24 hours? Would reduce the bandwidth on S3 perhaps.

I’m trying to understand our caching setup a bit better with Fastly<->S3, given bandwidth between S3 and fastly is our largest cost.

I noticed we’re not serving any Cache-Control headers on our NAR files, but I think we could set Cache-Control: immutable on all NAR objects in S3 as NAR files are content-addressed they should never change? Fastly respects these response headers to decide how long to cache things for.

Do I understand correctly that

https://github.com/NixOS/infra/blob/88f1c42e90ab88673ddde3bf973330fb2fcf23be/terraform/cache.tf#L138C17-L138C22

is the only thing configuring how long we hold things in cache? (seems to be 24 hours).

Given we also cache 404s on narinfos I guess that makes sense as we want them to be fast. ( and In case the narinfo gets uploaded later it invalidates it). But can’t we cache NARs way more aggressively than 24 hours? Would reduce the bandwidth on S3 perhaps.

I’m trying to understand our caching setup a bit better with Fastly<->S3, given bandwidth between S3 and fastly is our largest cost.

I noticed we’re not serving any Cache-Control headers on our NAR files, but I think we could set Cache-Control: immutable on all NAR objects in S3 as NAR files are content-addressed they should never change? Fastly respects these response headers it receives from S3 to decide how long to cache things for.

Do I understand correctly that

https://github.com/NixOS/infra/blob/88f1c42e90ab88673ddde3bf973330fb2fcf23be/terraform/cache.tf#L138C17-L138C22

is the only thing configuring how long we hold things in cache? (seems to be 24 hours).

Given we also cache 404s on narinfos I guess that makes sense as we want them to be fast. ( and In case the narinfo gets uploaded later it invalidates it). But can’t we cache NARs way more aggressively than 24 hours? Would reduce the bandwidth on S3 perhaps.