Re: Yet another Hydra mirror: hydra-mirror.marusich.info

[ludo@gnu.org (Ludovic Courtès)]

Chris Marusich <cmmarusich@gmail.com> skribis:

> ludo@gnu.org (Ludovic Courtès) writes:
>
>> Yeah, mirror.guixsd.org also caches for one week now.  I wasn’t sure how
>> much disk space that would represent, but so far we’re around 10G, so
>> increasing to 1 week seemed reasonable.
>
> Are there any URL paths a caching proxy should NOT cache for a long
> time? My understanding is that it's OK to cache all URL paths for 1
> week. Are there any URL paths for which I should return something
> different from Hydra (e.g., /nix-cache-info)?

Everything can be cached, where “everything” really means:

  /nix-cache-info
  /.*\.narinfo$
  /nar/.*

The rest should not be proxied at all, because it’s dynamic in nature
and some of it is quite expensive to generate (things that involve
complex SQL queries.)

>> OK.
>>
>> Do you know exactly how much is cached?  Also, when does caching happen?
>
> Every OK result is cached for 7 days. My understanding is that negative
> results (e.g., 404) are not cached. The storage limit is effectively
> unlimited from my perspective, since CloudFront is a service.

Good.  :-)

>> When using nginx as a proxy as on mirror.guixsd.org, it fetches things
>> lazily, so on a cache miss it goes connect to hydra.gnu.org.
>
> CloudFront operates the same way.

Yeah, I’ve seen from the headers that it runs nginx.

Thanks,
Ludo’.