How do I find which revision of #nixos nixpkgs-unstable is available in cache for darwin-x86_64? Every time I update to latest unstable revision, I have to rebuild a lot of packages and it takes hours.

@abnv https://hydra.nixos.org/jobset/nixpkgs/trunk take the one with a lot of greens, avoid those with a lot of grey

@raito Thanks. Running `flake update` defaulted to using the first revision in that list but that leads to a lot of building on my MacBook. Any idea how I use a different revision from the Hydra build history? It seems I need the SRI hash but I can't find it anywhere on the Hydra build pages.

@abnv apologies I don't have the flake CLI in mind but you can do something like github:nixpkgs/$revision and let nix flake lock --update-input update the SRI hashes for you

@raito Thanks, that worked! I used one revision before the latest and there was no building. It's a pity that I have to do this manually though instead of `flake update` taking care of it automatically.

PS: the flake URL syntax is `github:nixos/nixpkgs?rev=$rev`.

@abnv I guess it's a bit out of scope for flakes because they do not have the semantics of our nixpkgs channels unfortunately.

@raito which semantics are you talking about? Maybe I can write a script to automate it with flakes.

@abnv a revision completely built by Hydra vs a revision not completely built by Hydra, etc.

a revision completely tested by Hydra, etc.