CI workflow for Nix appears completely broken by Cachix

[meejah]

For example:

Building PR for user/org: tahoe-lafs
Building branch: pull/1394
Non-upstream build.
Cache not required.
Cache not writeable.
Cachix credentials missing; will not attempt cache writes.
error: unexpected EOF reading a line

Exited with code exit status 1

[hacklschorsch]

The error: unexpected EOF reading a line comes from Nix waiting for an answer to an interactive prompt that never comes:

do you want to allow configuration setting 'substituters' to be set to '​https://tahoe-lafs-opensource.cachix.org' (y/N)? error: unexpected EOF reading a line

I added flags to make nix more trusting in ​https://github.com/tahoe-lafs/tahoe-lafs/pull/1398

[meejah]

In N&B today it was said this was closed in error. Reopened.

[btlogy]

I wonder how bad these 3 builds will look like on Github w/o caching. I'm going to try a workflow inspired on the one I'm using already elsewhere...

[btlogy]

Ok, same as Flo said in the N&B earlier: the same job on Github is also re-building the whole world from scratch... We likely need to bump nixpkgs in the flake to nixos-24.05 which is deprecated but should still be in caches. Because our current jobs are still based on nixos-23.05 and even nixos-22.11 which are nowhere to be found (outside Cachix maybe).

[btlogy]

Flo and I made some progress: updating everything to nixos-24_11 (released a few days ago) seems to work decently w/o our Cachix, because the public cache holds most of the binaries we need.

I've squashed and rework our commits to prepare a meaningful PR:

• ​https://github.com/tahoe-lafs/tahoe-lafs/pull/1403

REM: the proposed change is also dropping the nix packaging and testing of Tahoe-LAFS on Python 3.9 in favor of doing it now on Python 3.12.

[hacklschorsch]

Fixed in ​https://github.com/tahoe-lafs/tahoe-lafs/pull/1403