[Nix-dev] still waiting for https://cache.nixos.org after 5 seconds...

[Graham Christensen]

Denis <denis at camfex.cz> writes:

> There are many issues with cache.nixos.org (slowness in some regoins,
> downtimes) so setting up a second CDN would be useful. It is for free.

Hi,

Unfortunately, these problems are very hard to diagnose. More often than
not, the issue is between the user and AWS.

I have a tool that provides information to help Amazon debug the
problem:

https://gist.github.com/grahamc/df1bb806eb3552650d03eef7036a72ba

If you run this when when you are having issues, please send the results
to me and I'll collect them.

Cloudfront is an extremely stable platform (along the axis of
"availability") to build off of. They promise a minimum of 99.9%[0] of
all requests will be correctly serviced, while simultaneously providing
edge-caching to improve performance in certain regions.

Our Cloudfront distribution is backed by S3, a similar promise of 99.9%
availability[1]. S3 provides additional guarantees, like its durability
(99.999999999% [2].)

Our cloudfront distribution sees almost almost 100,000 unique users each
month, each downloading hundreds or thousands of NARs and narinfo files.
At the size of the cache (many TBs) and traffic it sees, these numbers
aren't an easy feat.

0: https://aws.amazon.com/cloudfront/sla/
1: https://aws.amazon.com/s3/sla/
2: https://aws.amazon.com/s3/faqs/

Best,
Graham