WASM Nix build script

flake.nix

# ...

        # nix run .#wasm-packages
        apps.wasm-packages = {
          type = "app";
          program = toString (pkgs.writeShellScript "wasm-packages" ''
            ${wasmPackScript { packageName = "somepkg-wasm"; }}/bin/wasmPackScript
          '');
        };

wasmPackScript.nix

{ lib, stdenv, pkgs, rust }:

{ packageName }:
pkgs.writeShellApplication rec {
  name = "wasmPackScript";

  text = ''
    outdir="$WORKSPACE_ROOT/packages/@mytunes/${packageName}"
    pushd "$WORKSPACE_ROOT/rust-packages/${packageName}"

    rm -rf outdir
    mkdir -p "$outdir"

    # TODO remove workaround for https://github.com/rustwasm/wasm-pack/issues/1263
    mkdir -p "$outdir/tmpbin/bin"
    cp "${pkgs.binaryen}/bin/wasm-opt" "$outdir/tmpbin/bin"
    cp "${pkgs.binaryen}/bin/wasm-opt" "$outdir/tmpbin"
    export PATH="$outdir/tmpbin:$PATH"

    # TODO fix warning: (SSL certificate problem: unable to get local issuer certificate)
    wasm-pack build --out-dir "$outdir" --scope "mytunes" --target web --release

    # Add newline otherwise Yarn will try to reformat the `package.json`
    printf "\n" >> "$outdir"/package.json

    # Only git-ignore the wasm files
    printf "*.wasm" > "$outdir"/.gitignore

    echo "Contents of $outdir:"
    ls -la "$outdir"
  '';

  runtimeInputs = [
    pkgs.wasm-pack
    pkgs.wasm-bindgen-cli # needed for wasm-pack
    pkgs.binaryen # needed for wasm-pack
    pkgs.cargo
    rust
  ];

}