Easier per-project cachix configuration

[zimbatm]

Cater for the following scenario:

$ cd projectA
$ nix-build # this should use the binary cache of projectA
$ cd ../projectB
$ nix-build # this should use the binary cache of projectB

Ideally both projects don't need any configuration and nix-build knows how to use the right binary cache.

Potentially introduce a cachix run -- dispatcher that wraps all the nix CLI tools with the right config.

[domenkozar]

Relevant: #5

[domenkozar]

I was thinking something like:

cachix run <name1> <name2> -- nix-build would be a scoped run of the two binary caches. I wonder what are the drawbacks?

[domenkozar]

Similar use case is hashbang scripts, cachix could provide a binary cache temporary only for the script being ran.

[jezen]

I was going to open a new issue for this question, but it seems somewhat relevant to this thread.

I manage a few different Haskell projects. Many of the dependencies are shared. Should each project have its own binary cache? Or should I have a general binary cache — like cachix create jezen or something — and use that all the time?

[domenkozar]

What could work is that shell.nix would set something like:

shellHook = ''
  export XDG_CONFIG_HOME = $(pwd);
'';

and then running something like cachix authtoken && cachix use in the shell.

Confirmed by @betaboon that this works! Note that you have to put nix/nix.conf and nix/netrc into .gitignore (or git-encrypt) it.