ok, got it working! basically, it’s possible also to write it in the “sha256:…” format, with the output given in the error. So, the final config snippet would be:
extensions =
let
createChromiumExtensionFor = browserVersion: { id, sha256, version }:
{
inherit id;
crxPath = builtins.fetchurl {
url = "https://clients2.google.com/service/update2/crx?response=redirect&acceptformat=crx2,crx3&prodversion=${browserVersion}&x=id%3D${id}%26installsource%3Dondemand%26uc";
name = "${id}.crx";
inherit sha256;
};
inherit version;
};
createChromiumExtension = createChromiumExtensionFor (lib.versions.major pkgs.ungoogled-chromium.version);
in
[
(createChromiumExtension {
# ublock origin
id = "cjpalhdlnbpafiamejdnhcphjbkeiagm";
sha256 = "sha256:026l3wq4x7rg9f0dz4xiig25x8b7h0syil1d09hbpfzv0yg5bm4m";
version = "1.37.2";
})
(createChromiumExtension {
# dark reader
id = "eimadpbcbfnmbkopoojfekhnkhdbieeh";
sha256 = "sha256:1xw996dmkzsx2pmilb3ivyfnjckm2g1f2sx10yd4nllqbz5076mm";
version = "4.9.34";
})
];
Ah - and in order to get the nix-prefetch-url working properly I just passed it the --name argument, so that it renames the file afterwards. I think it might be a bug in the code that manages the naming of the downloaded file?
λ nix-prefetch-url --name arst.crx 'https://clients2.google.com/service/u
redirect&acceptformat=crx2,crx3&prodversion=92&x=id%3Dcjpalhdlnbpafiamejd
allsource%3Dondemand%26uc'
path is '/nix/store/yh1zgrdab3k7c7ad3wa6nx785ckdwp8x-arst.crx'
026l3wq4x7rg9f0dz4xiig25x8b7h0syil1d09hbpfzv0yg5bm4m