Automate creating nix-shell environments with node2nix

npminstall.sh

#!/bin/bash

# Exit on any failure
set -e

if [ "$#" -lt 1 ]; then
	echo "Expected at least one parameter (npm package name)"
	exit 1
fi

NPM_PACKAGE_NAME="$1"
NPM_PACKAGE_VERSION="${2:-latest}"

echo "creating env for $NPM_PACKAGE_NAME:$NPM_PACKAGE_VERSION"

function fail_if_exists () {
	local FILE_NAME="$1"

	if [ -f "$FILE" ]; then
		echo "$FILE exists. Aborting to avoid overwriting it. Remove and retry if that's your intention"
		exit 1
	fi
}

fail_if_exists "default.nix"
fail_if_exists "node-env.nix"
fail_if_exists "node-packages.nix"
fail_if_exists "generated.nix"

cat <<EOT >> node2nix.nix
with import <nixpkgs> {};
stdenv.mkDerivation rec {
        name = "node2nix";
        buildInputs = [ nodePackages.node2nix ];
}
EOT

cat <<EOT >> package.json
{
        "name": "$NPM_PACKAGE_NAME",
        "version": "$NPM_PACKAGE_VERSION",
        "devDependencies": {
                "$NPM_PACKAGE_NAME": "$NPM_PACKAGE_VERSION"
        }
}
EOT

# Running it will create: default.nix, node-env.nix and node-package.nix
nix-shell node2nix.nix --run "node2nix --development"

mv default.nix generated.nix

cat <<EOT >> default.nix
let
  gen = import ./generated.nix;
in (gen { }).shell
EOT