cluster: Add support to cluster to work with 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 nodejs#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: nodejs#19026

Author: sameer-coder

lib/internal/cluster/master.js

@@ -102,11 +102,14 @@ 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.split(' ') : [];
 
   util._extend(workerEnv, env);
   workerEnv.NODE_UNIQUE_ID = '' + id;
 
-  if (execArgv.some((arg) => arg.match(debugArgRegex))) {
+  if (execArgv.some((arg) => arg.match(debugArgRegex)) ||
+      nodeOptions.some((arg) => arg.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 +1,27 @@
+'use strict';
+const common = require('../common');
+const cluster = require('cluster');
+const assert = require('assert');
+
+if (process.config.variables.node_without_node_options)
+  common.skip('missing NODE_OPTIONS support');
+
+
+checkForInspectSupport('--inspect');
+
+function checkForInspectSupport(flag) {
+  const env = Object.assign({}, process.env, { NODE_OPTIONS: flag });
+  const o = JSON.stringify(flag);
+
+  if (cluster.isMaster) {
+    cluster.fork(env);
+
+    cluster.on('online', (worker) => {
+      process.exit(0);
+    });
+
+    cluster.on('exit', (worker, code, signal) => {
+      assert.fail(`For ${o}, failed to start a cluster with inspect option`);
+    });
+  }
+}