@Solene Firstly, I have discussed my views on the benefits of a global P2P cache at length in the previous posts:
But to summarize:
First we need to separate caching from archiving as these two have different optimization requirements. Archives require large storage but are not so concerned with bandwidth. However, caches care more about bandwidth than storage as they are updated and pruned regularly. For example: a package that is only being used by less than 10 people should probably be not in the cache as those 10 people can build it on their own machines or host a local cache if it is needed for a large set of machines. In such a case there should be a Network Admin who is running the show anyway…
It is my understanding that the only thing that needs data persistence is the tarball archive for software where the source code is not freely available for compiling from source. All other data can be rebuilt if it is missing from the P2P network when or if needed.
Yes, I know that the data persistence problem has been solved for now via the deal with a CDN.
However, bandwidth cost are also an ongoing concern if the Nix community continues to grow. My concern is that it seems the current model has the cache system merged with the archive system as a few people have been asking me how P2P solves data persistence, and I feel like they are missing the point I am trying to make. P2P solves the cache (distribution) side of the problem not the archive (persistence) side. But if Nix is reproducible (I know there are some limits to this) then persistence is not the main problem in the first place, it is the cache (distribution) side that is the main ongoing problem of concern.
If P2P is successful, then we can have Hydra be the system that seeds the P2P network as the “trusted-node”, and if there are a large number of nodes hosting a certain piece of data then the CDN can be pruned without fear of a loss of cache performance (as the P2P network is supplying the bandwidth). This pruning can be done organically instead of by necessity (if we have this crisis arise again in the future requiring a serious prune all at once manually by a person which could lead to real headaches for many people.)
I know there are people who are not keen on P2P for various reasons, but one of the main reasons why I am so strongly for it is because I believe it will make the Nix ecosystem future proof and build redundancy into into the system as a whole. (I am thinking 100 years future proof here)
@RaitoBezarius I see that you said someone just needs to make it and add nix.experimental.p2p-cache.enable? But who approves that if not the Foundation? I seem to be missing something here…
If that is the case, then there are a couple of working packages already in nixpkgs from what I have seen. If they can be ported under a main Nix config option then we can all test together globally then work out the bugs as we find them. For P2P to work it requires everyone to be on the same network and same protocol to concentrate the collective bandwidth, othewise P2P won’t work at scale.
There is a chance (10 years in the future) that a successful P2P network can replace most of what is on the CDN, which will save a serious amount of money for someone, which can then be used to pay more Nix devs at the Foundation. Money spent on talent is better than it spent on infrastructure IMHO.
Thanks for the comments I appreciate them very much.