pkgs: add `fetch-node-modules`

flake.nix

@@ -73,7 +73,13 @@
         nbPkgs = self.lib.mkNbPkgs { inherit system pkgs; };
       in rec {
         packages = flake-utils.lib.flattenTree (removeAttrs nbPkgs [
-          "pinned" "modulesPkgs" "nixops19_09" "krops" "generate-secrets" "netns-exec"
+          "fetchNodeModules"
+          "krops"
+          "modulesPkgs"
+          "netns-exec"
+          "nixops19_09"
+          "pinned"
+          "generate-secrets"
         ]) // {
           inherit (import ./examples/qemu-vm/minimal-vm.nix self pkgs system)
             # A simple demo VM.

pkgs/build-support/fetch-node-modules.nix

@@ -0,0 +1,74 @@
+# This is a modified version of
+# https://github.com/NixOS/nixpkgs/pull/128749
+
+{ lib, stdenvNoCC, makeWrapper, nodejs }:
+
+{ src
+, hash ? ""
+, runScripts ? false
+, preferLocalBuild ? true
+, npmFlags ? ""
+, ...
+} @ args:
+stdenvNoCC.mkDerivation ({
+  inherit src preferLocalBuild;
+
+  name = "${src.name}-node_modules";
+  nativeBuildInputs = [
+    makeWrapper
+    (if args ? nodejs then args.nodejs else nodejs)
+  ];
+
+  outputHashMode =  "recursive";
+
+  impureEnvVars = lib.fetchers.proxyImpureEnvVars;
+
+  phases = "unpackPhase patchPhase buildPhase installPhase";
+
+  buildPhase = ''
+    runHook preBuild
+
+    if [[ ! -f package.json ]]; then
+        echo "Error: file `package.json` doesn't exist"
+        exit 1
+    fi
+    if [[ ! -f package-lock.json ]]; then
+        echo "Error: file `package-lock.json` doesn't exist"
+        exit 1
+    fi
+
+    export SOURCE_DATE_EPOCH=1
+    export npm_config_cache=/tmp
+    NPM_FLAGS="--omit=dev --omit=optional --no-update-notifier $npmFlags"
+    # Scripts may result in non-deterministic behavior.
+    # Some packages (e.g., Puppeteer) use postinstall scripts to download extra data.
+    if [[ ! $runScripts ]]; then
+        NPM_FLAGS+=" --ignore-scripts"
+    fi
+
+    echo "Running npm ci $NPM_FLAGS"
+    npm ci $NPM_FLAGS
+
+    cp package.json \
+       package-lock.json node_modules/
+    rm -f node_modules/.package-lock.json
+
+    runHook postBuild
+  '';
+
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p $out/lib
+    cp -r node_modules $out/lib
+
+    runHook postInstall
+  '';
+} // (
+  if hash == "" then {
+    outputHashAlgo = "sha256";
+    outputHash = "";
+  } else {
+    outputHash = hash;
+  }
+) // (builtins.removeAttrs args [ "hash" ]))

pkgs/default.nix

@@ -25,6 +25,8 @@ let self = {
     packageOverrides = import ./python-packages self;
   }).pkgs;
 
+  fetchNodeModules = pkgs.callPackage ./build-support/fetch-node-modules.nix { };
+
   # Fix clightning build by using python package mistune 0.8.4, which is a
   # strict requirement. This version is affected by CVE-2022-34749, but this
   # is irrelevant in this context.