`nix-index` fails due to `mesos` not being found

[OleMussmann]

The package comma fails for me, because nix-index can't, well, index anymore. I'm not sure if nix-index is choking, or if nix-env is to blame.

$ nix-index
+ querying available packages
error: querying available packages failed
caused by: nix-env failed with error: nix-env failed with exit code 1:
error: attribute 'mesos' missing

       at /nix/var/nix/profiles/per-user/root/channels/nixos/pkgs/development/haskell-modules/configuration-nix.nix:143:24:

          142|     # Pass _only_ mesos; the correct protobuf is propagated.
          143|     extraLibraries = [ pkgs.mesos ];
             |                        ^
          144|     preConfigure = "sed -i -e /extra-lib-dirs/d -e 's|, /usr/include, /usr/local/include/mesos||' hs-mesos.cabal";
       Did you mean one of meson, ecos, geos, less or memo?
(use '--show-trace' to show detailed location information)

$ nix-index --version
nix-index 0.1.5

$ nixos-version --json
{"nixosVersion":"22.11.20230524.99fe1b8","nixpkgsRevision":"99fe1b870522d6ee3e692c2b6e663d6868a3fde4"}

[Shiryel]

I was having this issue, because I was using Nix flakes without updating the Nix channels.

This problem happens because nix-index expects an updated <nixpkgs> channel.

I fixed this issue by syncing the NIX_PATH with the current version of my nixpkgs input (from flake.nix):

{
  nix.nixPath = [ "nixpkgs=${nixpkgs.outPath}" ];
}

Note that you also need nix.channel.enable to be true (the default)

[Emil Nikolov]

I am also getting this error. Aren't flakes a replacement for channels? Why are they still needed for this?

[Ryan Lahfa]

I am also getting this error. Aren't flakes a replacement for channels? Why are they still needed for this?

Flakes are an experimental feature, they are no replacement to channels today except if you know what you are doing.

[Emil Nikolov]

I just wasn't aware that it's possible to use channels when using flakes. I got started with flakes directly and have never used channels.