plugins: Helper function to run the npm CLI

src/node/utils/run_npm.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const log4js = require('log4js');
+const runCmd = require('./run_cmd');
+
+const logger = log4js.getLogger('runNpm');
+const npmLogger = log4js.getLogger('npm');
+
+const stdoutLogger = (line) => npmLogger.info(line);
+const stderrLogger = (line) => npmLogger.error(line);
+
+/**
+ * Wrapper around `runCmd()` that logs output to an npm logger by default.
+ *
+ * @param args Command-line arguments to pass to npm.
+ * @param opts See the documentation for `runCmd()`. The `stdoutLogger` and `stderrLogger` options
+ *     default to a log4js logger.
+ *
+ * @returns A Promise with additional `stdout`, `stderr`, and `child` properties. See the
+ *     documentation for `runCmd()`.
+ */
+module.exports = exports = (args, opts = {}) => {
+  const cmd = ['npm', ...args];
+  logger.info(`Executing command: ${cmd.join(' ')}`);
+  const p = runCmd(cmd, {stdoutLogger, stderrLogger, ...opts});
+  p.then(
+      () => logger.info(`Successfully ran command: ${cmd.join(' ')}`),
+      () => logger.error(`npm command failed: ${cmd.join(' ')}`));
+  // MUST return the original Promise returned from runCmd so that the caller can access stdout.
+  return p;
+};
+
+// Log the version of npm at startup.
+let loggedVersion = false;
+(async () => {
+  if (loggedVersion) return;
+  loggedVersion = true;
+  const p = runCmd(['npm', '--version'], {stdoutLogger: null, stderrLogger});
+  const chunks = [];
+  await Promise.all([
+    (async () => { for await (const chunk of p.stdout) chunks.push(chunk); })(),
+    p, // Await in parallel to avoid unhandled rejection if np rejects during chunk read.
+  ]);
+  const version = Buffer.concat(chunks).toString().replace(/\n+$/g, '');
+  logger.info(`npm --version: ${version}`);
+})().catch((err) => {
+  logger.error(`Failed to get npm version: ${err.stack}`);
+  // This isn't a fatal error so don't re-throw.
+});