feat: support installation from custom NPM registry

read and respect registry configuration from .npmrc if it exists

Author: Eynorey

README.md

@@ -52,6 +52,10 @@ If `run_install` is a YAML string representation of either an object or an array
 
 This is useful when you want to use a incompatible pair of Node.js and pnpm.
 
+## Registry Configuration
+
+The action automatically respects custom registry configuration from `.npmrc` files in your workspace root. If a `.npmrc` file exists and contains a `registry=` line, the action will use that registry URL to install pnpm. Otherwise, the default npm registry will be used.
+
 ## Outputs
 
 ### `dest`
@@ -83,7 +87,7 @@ jobs:
           version: 10
 ```
 
-###  Install only pnpm with `packageManager`
+### Install only pnpm with `packageManager`
 
 Omit `version` input to use the version in the [`packageManager` field in the `package.json`](https://nodejs.org/api/corepack.html).
 

dist/index.js

@@ -6,10 +6,12 @@ import path from 'path'
 import { execPath } from 'process'
 import util from 'util'
 import { Inputs } from '../inputs'
+import { readNpmrcRegistry } from '../utils'
 import YAML from 'yaml'
 
 export async function runSelfInstaller(inputs: Inputs): Promise<number> {
   const { version, dest, packageJsonFile, standalone } = inputs
+  const { GITHUB_WORKSPACE } = process.env
 
   // prepare self install
   await rm(dest, { recursive: true, force: true })
@@ -21,7 +23,18 @@ export async function runSelfInstaller(inputs: Inputs): Promise<number> {
 
   // prepare target pnpm
   const target = await readTarget({ version, packageJsonFile, standalone })
-  const cp = spawn(execPath, [path.join(__dirname, 'pnpm.cjs'), 'install', target, '--no-lockfile'], {
+  const installArgs = [path.join(__dirname, 'pnpm.cjs'), 'install', target, '--no-lockfile']
+
+  if (GITHUB_WORKSPACE) {
+    const customRegistry = await readNpmrcRegistry(GITHUB_WORKSPACE)
+
+    if (customRegistry) {
+      installArgs.push('--registry', customRegistry)
+    }
+  }
+
+  // run self-install
+  const cp = spawn(execPath, installArgs, {
     cwd: dest,
     stdio: ['pipe', 'inherit', 'inherit'],
   })

src/install-pnpm/run.ts

@@ -1,5 +1,8 @@
+import { debug, info, warning } from '@actions/core'
+import { readFile } from 'fs/promises'
 import path from 'path'
 import process from 'process'
+import util from 'util'
 import { Inputs } from '../inputs'
 
 export const getBinDest = (inputs: Inputs): string => path.join(inputs.dest, 'node_modules', '.bin')
@@ -8,3 +11,50 @@ export const patchPnpmEnv = (inputs: Inputs): NodeJS.ProcessEnv => ({
   ...process.env,
   PATH: getBinDest(inputs) + path.delimiter + process.env.PATH,
 })
+
+/**
+ * Reads and parses a potential .npmrc file to extract registry configuration
+ * @param workspaceRoot - The root directory of the workspace
+ * @returns The registry URL if found, otherwise undefined
+ */
+export async function readNpmrcRegistry(workspaceRoot: string): Promise<string | undefined> {
+  try {
+    const npmrcPath = path.join(workspaceRoot, '.npmrc');
+
+    debug(`Attempting to read .npmrc file from: ${npmrcPath}`);
+    const content = await readFile(npmrcPath, 'utf8');
+
+    for (const line of content.split('\n')) {
+      const trimmedLine = line.trim();
+
+      // skip comments and empty lines
+      if (!trimmedLine || /^[#;]/.test(trimmedLine)) {
+        continue;
+      }
+
+      const match = trimmedLine.match(/^registry\s*=\s*(.+)$/);
+      if (match) {
+        const registry = match[1].trim();
+
+        if (!/^https?:\/\//.test(registry)) {
+          warning(`Invalid registry URL format in .npmrc (must be http/https): ${registry}`);
+          continue;
+        }
+
+        info(`Using custom registry from .npmrc: ${registry}`);
+        return registry;
+      }
+    }
+
+    debug('No valid registry configuration found in .npmrc, using default NPM registry');
+  } catch (error) {
+    if (util.types.isNativeError(error) && 'code' in error && error.code === 'ENOENT') {
+      debug('No .npmrc file found, using default NPM registry');
+    } else {
+      const errorMessage = util.types.isNativeError(error) ? error.message : String(error);
+      warning(`Error reading .npmrc file: ${errorMessage}`);
+    }
+  }
+  
+  return;
+}