pm2/lib/God/ClusterMode.js

Production process manager for Node.JS applications with a built-in load balancer.

/**
 * Copyright 2013-present the PM2 project authors. All rights reserved.
 * Use of this source code is governed by a license that
 * can be found in the LICENSE file.
 */
'use strict';

/**
 * @file Cluster execution functions related
 * @author Alexandre Strzelewicz <as@unitech.io>
 * @project PM2
 */
var cluster       = require('cluster');
var path          = require('path');
var Utility       = require('../Utility.js');
var pkg           = require('../../package.json');
var typestrip     = require('../tools/typestrip.js');
var StdioLogger   = require('./StdioLogger.js');

/**
 * Description
 * @method exports
 * @param {} God
 * @return
 */
module.exports = function ClusterMode(God) {

  /**
   * For Node apps - Cluster mode
   * It will wrap the code and enable load-balancing mode
   * @method nodeApp
   * @param {} env_copy
   * @param {} cb
   * @return Literal
   */
  God.nodeApp = function nodeApp(env_copy, cb){
    var clu = null;

    console.log(`App [${env_copy.name}:${env_copy.pm_id}] starting in -cluster mode-`)
    if (env_copy.node_args && Array.isArray(env_copy.node_args)) {
      cluster.settings.execArgv = env_copy.node_args;
    }

    // Cluster workers run on the daemon's node, whose version can differ
    // from the CLI that resolved the interpreter: ensure type stripping
    // is active for .ts apps when this node needs the flag
    if (path.extname(env_copy.pm_exec_path || '') === '.ts' &&
        typestrip.supportLevel(process.versions.node) === 'flag' &&
        cluster.settings.execArgv.indexOf('--experimental-strip-types') === -1) {
      cluster.settings.execArgv = cluster.settings.execArgv.concat('--experimental-strip-types');
    }

    env_copy._pm2_version = pkg.version;

    // The worker's stdout/stderr are piped to the daemon (cluster silent
    // mode) instead of inheriting the daemon's fds: writes that bypass the
    // process.stdout.write hook of ProcessContainer.js (pino/sonic-boom,
    // children spawned with stdio 'inherit' like `npm start`...) used to
    // land in pm2.log (#3675 #4719 #4872 #4916 #4953 #5633)
    var stds = StdioLogger.stdsFromEnv(env_copy);

    // open() and not Utility.startLogging: files created here (as root) are
    // chowned to the app uid/gid the worker switches to before reopening them
    StdioLogger.open(stds, env_copy, function(err) {
      if (err) {
        God.logAndGenerateError(err);
        return cb(err);
      }

      try {
        // node.js cluster clients can not receive deep-level objects or arrays in the forked process, e.g.:
        // { "args": ["foo", "bar"], "env": { "foo1": "bar1" }} will be parsed to
        // { "args": "foo, bar", "env": "[object Object]"}
        // So we passing a stringified JSON here.
        clu = cluster.fork({pm2_env: JSON.stringify(env_copy), windowsHide: true});
      } catch(e) {
        God.logAndGenerateError(e);
        StdioLogger.close(stds);
        return cb(e);
      }

      clu.pm2_env = env_copy;

      var stdio = StdioLogger.attach(God, clu.process, env_copy, stds);

      // Pipes closed and not the Worker 'exit': exit is relayed from ChildProcess
      // exit, which fires before the stdio pipes are drained. Data still in
      // flight (or written by an stdio-inherit child outliving the worker)
      // would hit closed streams and be dropped from the log files
      var closed = false;

      StdioLogger.onPipesClosed(clu.process, function cluCloseLogs() {
        closed = true;
        try {
          stdio.flush();
          StdioLogger.close(stds);
        } catch(e) { God.logAndGenerateError(e); }
      });

      // A stopped app stays in clusters_db: reloading its logs must not
      // reopen streams nobody will ever close (fd leak)
      clu._reloadLogs = function(cb) {
        if (closed) return cb();
        try {
          StdioLogger.close(stds);
        } catch(e) { God.logAndGenerateError(e); }
        StdioLogger.open(stds, env_copy, function(err) {
          // worker closed while reopening
          if (closed) {
            try { StdioLogger.close(stds); } catch(e) {}
          }
          return cb(err);
        });
      };

      bindMessages(clu);

      return cb(null, clu);
    });
  };

  function bindMessages(clu) {

    /**
     * Broadcast message to God
     */
    clu.on('message', function cluMessage(msg) {
      /*********************************
       * If you edit this function
       * Do the same in ForkMode.js !
       *********************************/
      if (msg.data && msg.type) {
        return God.bus.emit(msg.type ? msg.type : 'process:msg', {
          at      : Utility.getDate(),
          data    : msg.data,
          process :  {
            pm_id      : clu.pm2_env.pm_id,
            name       : clu.pm2_env.name,
            rev        : (clu.pm2_env.versioning && clu.pm2_env.versioning.revision) ? clu.pm2_env.versioning.revision : null,
            namespace  : clu.pm2_env.namespace
          }
        });
      }
      else {

        if (typeof msg == 'object' && 'node_version' in msg) {
          clu.pm2_env.node_version = msg.node_version;
          return false;
        }

        return God.bus.emit('process:msg', {
          at      : Utility.getDate(),
          raw     : msg,
          process :  {
            pm_id      : clu.pm2_env.pm_id,
            name       : clu.pm2_env.name,
            namespace  : clu.pm2_env.namespace
          }
        });
      }
    });
  }
};