pnpm support

These changes build on top of [existing corepack support](#1222) to allow `pnpm` to be installed via [Corepack](https://nodejs.org/docs/latest/api/corepack.html).

The build process has also been modified use the `pnpm` binary at the following stages:
- installing dependencies
- running build scripts:
  - `heroku-prebuild`
  - `build` (or `heroku-postbuild`)
  - `heroku-cleanup`
- pruning dev dependencies

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## [Unreleased]
 
 - Support [Corepack](https://nodejs.org/api/corepack.html) installation of [Yarn](https://yarnpkg.com/) ([#1222](https://github.com/heroku/heroku-buildpack-nodejs/pull/1222))
+- Support [pnpm](https://pnpm.io/) ([#1224](https://github.com/heroku/heroku-buildpack-nodejs/pull/1224))
 
 ## [v240] - 2024-03-27
 

bin/compile

@@ -102,6 +102,7 @@ meta_set "build-step" "init"
 [ -e "$BUILD_DIR/node_modules" ] && PREBUILD=true || PREBUILD=false
 [ -f "$BUILD_DIR/yarn.lock" ] && YARN=true || YARN=false
 [ -f "$BUILD_DIR/package-lock.json" ] && NPM_LOCK=true || NPM_LOCK=false
+[ -f "$BUILD_DIR/pnpm-lock.yaml" ] && PNPM=true || PNPM=false
 YARN_2=$(detect_yarn_2 "$YARN" "$BUILD_DIR")
 
 ### Save build info
@@ -257,9 +258,23 @@ install_bins() {
     fi
   fi
 
+  if $PNPM; then
+    meta_set "build-step" "install-pnpm-using-corepack"
+    if [[ "$package_manager" == pnpm* ]]; then
+      package_manager="$package_manager"
+    else
+      warn "Currently pnpm installation is only supported through the 'packageManager' field in package.json"
+      fail
+    fi
+    monitor "install-pnpm-using-corepack" install_pnpm_using_corepack_package_manager "$package_manager" "$node_version"
+  fi
+
   if $YARN; then
     mcount "version.yarn.$(yarn --version)"
     meta_set "yarn-version" "$(yarn --version)"
+  elif $PNPM; then
+    mcount "version.pnpm.$(pnpm --version)"
+    meta_set "pnpm-version" "$(pnpm --version)"
   else
     mcount "version.npm.$(npm --version)"
     meta_set "npm-version" "$(npm --version)"
@@ -344,6 +359,8 @@ build_dependencies() {
     yarn_2_install "$BUILD_DIR"
   elif $YARN; then
     yarn_node_modules "$BUILD_DIR"
+  elif $PNPM; then
+    pnpm_install "$BUILD_DIR"
   elif $PREBUILD; then
     echo "Prebuild detected (node_modules already exists)"
     npm_rebuild "$BUILD_DIR"
@@ -388,6 +405,8 @@ cache_build() {
 prune_devdependencies() {
   if $YARN || $YARN_2; then
     yarn_prune_devdependencies "$BUILD_DIR" "$YARN_CACHE_FOLDER" "$BP_DIR"
+  elif $PNPM; then
+    pnpm_prune_devdependencies "$BUILD_DIR"
   else
     npm_prune_devdependencies "$BUILD_DIR"
   fi

lib/binaries.sh

@@ -142,6 +142,14 @@ install_yarn_using_corepack_package_manager() {
   echo "Using yarn $(yarn --version)"
 }
 
+install_pnpm_using_corepack_package_manager() {
+  local package_manager="$1"
+  local node_version="$2"
+  install_corepack_package_manager "$package_manager" "$node_version"
+  suppress_output pnpm --version
+  echo "Using pnpm $(pnpm --version)"
+}
+
 install_corepack_package_manager() {
   local node_major_version
   local node_minor_version

lib/dependencies.sh

@@ -33,6 +33,9 @@ run_if_present() {
       if [[ -n "$script" ]]; then
         monitor "${script_name}-script" yarn run "$script_name"
       fi
+    elif $PNPM; then
+      echo "Running $script_name"
+      monitor "${script_name}-script" pnpm run --if-present "$script_name"
     else
       echo "Running $script_name"
       monitor "${script_name}-script" npm run "$script_name" --if-present
@@ -65,6 +68,14 @@ run_build_if_present() {
           monitor "${script_name}-script" yarn run "$script_name"
         fi
       fi
+    elif $PNPM; then
+      echo "Running $script_name"
+      if [[ -n $NODE_BUILD_FLAGS ]]; then
+        echo "Running with $NODE_BUILD_FLAGS flags"
+        monitor "${script_name}-script" pnpm run --if-present "$script_name" -- "$NODE_BUILD_FLAGS"
+      else
+        monitor "${script_name}-script" pnpm run --if-present "$script_name"
+      fi
     else
       echo "Running $script_name"
       if [[ -n $NODE_BUILD_FLAGS ]]; then
@@ -305,3 +316,47 @@ npm_prune_devdependencies() {
     meta_set "skipped-prune" "false"
   fi
 }
+
+pnpm_install() {
+  local build_dir=${1:-}
+
+  echo "Running 'pnpm install' with pnpm-lock.yaml"
+  cd "$build_dir" || return
+
+  monitor "pnpm-install" pnpm install --prod=false --frozen-lockfile 2>&1
+
+  # prune the store after install to remove any package versions which may have been upgraded/removed
+  # since the last install.
+  suppress_output pnpm store prune
+}
+
+pnpm_prune_devdependencies() {
+  local build_dir=${1:-}
+
+  cd "$build_dir" || return
+
+  # seems like we can't use prune without some workarounds because it triggers pre/post-install scripts
+  # and does not respect the `--ignore-scripts` argument:
+  # https://github.com/pnpm/pnpm/issues/5030
+  #
+  # so we're going to create a temporary .npmrc file which does allow us to set the ignore-scripts config:
+  # https://pnpm.io/npmrc#ignore-scripts
+  local app_npmrc="$build_dir/.npmrc"
+  local tmp_npmrc=$(mktemp)
+
+  # copy the original .npmrc if it exists
+  if [ -f "$app_npmrc" ]; then
+    cp "$app_npmrc" "$tmp_npmrc"
+  fi
+
+  # append the temporary configuration setting
+  echo -e "\nignore-scripts=true" >> "$app_npmrc"
+  pnpm prune --prod 2>&1
+
+  # restore the original .npmrc if it exists
+  if [ -f "$app_npmrc" ]; then
+    cp "$tmp_npmrc" "$app_npmrc"
+  fi
+
+  meta_set "skipped-prune" "false"
+}

test/fixtures/pnpm-7-pnp/.gitignore

@@ -0,0 +1,2 @@
+node_modules/
+.pnp.cjs

test/fixtures/pnpm-7-pnp/.npmrc

@@ -0,0 +1,2 @@
+node-linker=pnp
+symlink=false`

test/fixtures/pnpm-7-pnp/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "pnpm-7-pnp",
+  "version": "1.0.0",
+  "packageManager": "pnpm@7.32.3",
+  "engines": {
+    "node": "18.x"
+  },
+  "scripts": {
+    "heroku-prebuild": "echo 'heroku-prebuild'",
+    "build": "echo 'heroku-build'",
+    "heroku-cleanup": "echo 'heroku-cleanup'",
+    "start": "node ./server.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "fastify": "^4.26.2"
+  },
+  "devDependencies": {
+    "dotenv": "^16.4.5"
+  }
+}