Better error message when current schema is one version behind the latest one

[MidAutumnMoon]

After a flake update, colmena started to show following error message:

 while calling the 'throw' builtin
         at «string»:1:64:
            1| with builtins; hive: assert (hive.__schema == "v0.20241006" || throw ''
             |                                                                ^
            2|     The colmenaHive output (schema ${hive.__schema}) isn't compatible with this version of Colmena.

       error: The colmenaHive output (schema v0.5) isn't compatible with this version of Colmena.

       Hint: Use the same version of Colmena as in the Flake input

It's really confusing because I do uses colmena from upstream flake.

It took me a while to realize that the colmena currently installed is outdated because systems have yet been updated due to this error, and surely "v0.20241006" is older than "v0.5" :/ After updating with good old nixos-rebuild the error sure is gone.

I'd like to suggest that colmena gives a better hint, saying something like: "The schema v0.20241006 is from the previous version of colmena where the latest is v0.5. Use nixos-rebuild to update your system first to install the newer colmena".

[zhaofengli]

I'd like to suggest that colmena gives a better hint, saying something like: "The schema v0.20241006 is from the previous version of colmena where the latest is v0.5. Use nixos-rebuild to update your system first to install the newer colmena".

Would it help to clarify that it's a mismatch between the Colmena executable and the Colmena input in the flake? People get the colmena command via various ways and it's not always globally installed. Personally, I add it to the devShell in the same flake so the version is always consistent.

[MidAutumnMoon]

Would it help to clarify that it's a mismatch between the Colmena executable and the Colmena input in the flake?

I think this could be helpful. Using Github code search there are bunch of configs which install colmena globally, so it might beneficial for more people :)

I add it to the devShell

I used to do this too, but the experience isn't quite enjoyful so I opted into install apps globally.

[JonnyHaystack]

I'd like to suggest that colmena gives a better hint, saying something like: "The schema v0.20241006 is from the previous version of colmena where the latest is v0.5. Use nixos-rebuild to update your system first to install the newer colmena".

Would it help to clarify that it's a mismatch between the Colmena executable and the Colmena input in the flake? People get the colmena command via various ways and it's not always globally installed. Personally, I add it to the devShell in the same flake so the version is always consistent.

@zhaofengli would you mind providing a minimal example of a flake that does this? I'm having trouble figuring out how to pass the colmena flake input as a package for the devShell. Also struggled when trying to use flake-utils.lib.eachDefaultSystem for the devShell (as almost all examples tend to use it) while having the colmenaHive output separately

[HritwikSinghal]

@JonnyHaystack below works for me.

flake.nix

{
  inputs = {
    nixpkgs.url = "github:nixos/nixpkgs/master";
  
    colmena = {
      url = "github:zhaofengli/colmena";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    sops-nix = {
      url = "github:Mic92/sops-nix";
      inputs.nixpkgs.follows = "nixpkgs";
    };
  };

  outputs =
    {
      self,
      nixpkgs,
      colmena,
      sops-nix,
    }@inputs: {
      devShells = eachDefaultSystemMap (
        system:
        let
          pkgs = import nixpkgs {
            inherit system;
          };
        in
        {
          default = pkgs.callPackage ./shell.nix { inherit (inputs) sops-nix colmena; };
        }
      );
    };
}

shell.nix

{
  pkgs,
  colmena,
  sops-nix,
  ...
}:
mkShell {
  buildInputs = [
       colmena.defaultPackage.${pkgs.system}
  ];
}

In shell.nix, i have to use the package from flake instead of upstream nixpkgs (which is at 0.4.0), so colmena.defaultPackage.${pkgs.system} or colmena.packages.${pkgs.system}.colmena. Now my colmena version is 0.5.0-pre and that error is gone