cluster: add support for NODE_OPTIONS="--inspect"

When using cluster and --inspect as cli argument it is correctly
handled and each worker will use a different port, this was
fixed by #13619. But when env var NODE_OPTIONS="--inspect"
is set this logic doesn't apply and the workers will fail as they
try to attach to the same port.

Fixes: #19026

PR-URL: #19165
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

lib/internal/cluster/master.js

@@ -103,11 +103,14 @@ function createWorkerProcess(id, env) {
   const workerEnv = util._extend({}, process.env);
   const execArgv = cluster.settings.execArgv.slice();
   const debugArgRegex = /--inspect(?:-brk|-port)?|--debug-port/;
+  const nodeOptions = process.env.NODE_OPTIONS ?
+    process.env.NODE_OPTIONS : '';
 
   util._extend(workerEnv, env);
   workerEnv.NODE_UNIQUE_ID = '' + id;
 
-  if (execArgv.some((arg) => arg.match(debugArgRegex))) {
+  if (execArgv.some((arg) => arg.match(debugArgRegex)) ||
+      nodeOptions.match(debugArgRegex)) {
     let inspectPort;
     if ('inspectPort' in cluster.settings) {
       if (typeof cluster.settings.inspectPort === 'function')

test/parallel/test-inspect-support-for-node_options.js

@@ -0,0 +1,30 @@
+'use strict';
+const common = require('../common');
+const cluster = require('cluster');
+const assert = require('assert');
+
+common.skipIfInspectorDisabled();
+
+checkForInspectSupport('--inspect');
+
+function checkForInspectSupport(flag) {
+
+  const nodeOptions = JSON.stringify(flag);
+  const numWorkers = 2;
+  process.env.NODE_OPTIONS = flag;
+
+  if (cluster.isMaster) {
+    for (let i = 0; i < numWorkers; i++) {
+      cluster.fork();
+    }
+
+    cluster.on('online', (worker) => {
+      worker.disconnect();
+    });
+
+    cluster.on('exit', common.mustCall((worker, code, signal) => {
+      const errMsg = `For NODE_OPTIONS ${nodeOptions}, failed to start cluster`;
+      assert.strictEqual(worker.exitedAfterDisconnect, true, errMsg);
+    }, numWorkers));
+  }
+}