hex2nix

hex2nix is a command that generates correct Nix Expressions from the Hex.pm repository. It only generates those expressions for packages that have a buildable Build System. Right now that is rebar, rebar3, or make. It builds all of these with rebar3. That works for the vast majority of packages but not all.

Running hex2nix

Usage: hex2nix [-h [<output_path>]] [-r [<registry_url>]] [-c [<cache>]]
               [-h [<help>]]

  -o, --output-path   Output Path for the `hex-packages.nix` file
                      [default: ./]
  -r, --registry-url  The url of the registry to base generation on
                      [default:
                      https://s3.amazonaws.com/s3.hex.pm/registry.ets.gz]
  -c, --cache-result  Cache the result of package download so it can be
                      reused. This is primarily useful for testing.
                      [default: false]
  -h, --help          Print the help message for this command [default:
                      false]

You can run hex2nix with no arguments and it will dump a hex-packages.nix file in the current directory. Optionally, you can give it an output-path and point that to the erlang-modules directory of your nixpkgs repo. That is usually pkgs/development/erlang-modules. By default it pulls from the current canonical Hex.pm registry, however you can give it a different url if you so desire. Finally, you can tell it to cache the intermediate results. This is mostly useful during development of hex2nix so it doesn't have to redownload the entire package repository for every run.

Building hex2nix

Assuming you are using Nix, you can simply run make and it will build the command for you.