fix cardano-wallet nixos module

[clemenscodes]

This fixes #4522.

The option self.defaultPackage.${pkgs.system} does not contain a cardano-node package, it only contains a cardano-wallet package.

Currently users are required to override the services.cardano-node.package option manually by pointing to a compatible cardano-node package.

So we point to the correct cardano-node compatible with cardano-wallet by using self.packages.${pkgs.system}.cardano-node instead.

[abailly]

Thanks a lot for the PR @clemenscodes
I am not a nix expert, could you tell me how I can verify this PR indeed fixes the issue?

[clemenscodes]

Thanks a lot for the PR @clemenscodes I am not a nix expert, could you tell me how I can verify this PR indeed fixes the issue?

The fastest way to verify would be using NixOS and running the cardano-node and cardano-wallet services at the same time successfully, without having to specify the services.cardano-node.package option. However it is not required to use NixOS. We can first understand the core issue, where in last two lines it reports

line 26: /nix/store/vxwqzhjp4wfj42cm3ff42z3cgr7244vp-cardano-wallet-2024.3.27/bin/cardano-node: No such file or directory

So the script that runs the cardano-node refers to the cardano-node binary via the cardano-wallet-2024.3.27 derivation from the nix store, and it can't find it there. All that is required for this to work again is telling the cardano-node script to look for the cardano-node binary where it actually exists.

The cardano-wallet-2024.3.27 derivation is used because the cardano-wallet module declares

services.cardano-node.package = lib.mkDefault self.defaultPackage.${pkgs.system};

in flake.nix.

You can verify that this referenced cardano-node binary does not exist by building the package and verifying that the result does not contain the binary. This can be done by building self.defaultPackage.${pkgs.system} from the root directory of the master branch of the cardano-wallet repository. After completion this will place a result symlink in the same directory, which contains a bin directory. This should contain a cardano-node binary but it only contains a cardano-wallet binary.

nix --extra-experimental-features "nix-command flakes"  build .#defaultPackage.x86_64-linux
ls result/bin | grep cardano-node # fails

After confirming this, you can then build self.packages.${pkgs.system}.cardano-node and verify that now it indeed exists.

nix --extra-experimental-features "nix-command flakes"  build .#packages.x86_64-linux.cardano-node
ls result/bin | grep cardano-node # succeeds

If you have any more questions or issues with verifying this, feel free to reach out.

[abailly]

currently trying to test this change, nix takes ages to download and build 12GB of data

[abailly]

What I don't understand is that running nix build .#packages.x86_64-linux.cardano-node at the HEAD of master just works and gives the same result than doing it in your branch. What's the point?

[clemenscodes]

Yeah, it takes a lot of data, but fortunately you can garbage collect the data afterwards. The point is that the derivation you built with nix build .#packages.x86_64-linux.cardano-node differs from the derivation built with nix build .#defaultPackage.x86_64-linux. The latter is what is currently used in the cardano-wallet nixos module, but since the latter does not produce the cardano-node binary, it breaks the cardano-node nixos module. Note that defaultPackage.x86_64-linux is not the same derivation as packages.x86_64-linux.cardano-node. All I did was update the cardano-wallet nixos module to use the proper derivation that actually has the required cardano-node for the cardano-node nixos service.

[abailly]

Integration tests rely on Nix, I will need to create an internal PR to ensure this is validated by the CI.