cluster-manager

cluster-manager

Purpose

To manage apps that want to use nodejs cluster module. This module will restart workers on failure and allows rolling restarts. It can send email notifications on worker failure.

Install

npm install -g cluster-manager

Usage

var clusterManager = require('cluster-manager');

clusterManager({
    exec:"/PATH/TO/APPLICATION",
    workers: 5,
    notify:{
        from:"[e-mail]",
        to:"[e-mail]",
        subjectPrefix:"SUBJECT PREFIX"
    }
});

Options

Below are the keys that can be set in the JSON object. They are all optional except for exec.

exec

node application that will be started by the cluster

<dt>workers</dt>
<dd>number of workers that will be spawned. Default:2</dd>

<dt>pidfile</dt>
<dd>File to store the ID for the main process. Used to send signals to the cluster manager</dd>

<dt>notify</dt>
<dd>Object with a <i>from</i>, <i>to</i> and <i>subjectPrefix</i> property. If set, the recipient will receive email notifications on events that affect the workers. To send notifications, it requires __/usr/lib/sendmail__.</dd>

<dt>verbose</dt>
<dd>Handles if the cluster-manager will be verbose in its messages. Default:false</dd>

<dt>silent</dt>
<dd>Determines if the worker stdout streams are silent. Default:false</dd>

<dt>env</dt>
<dd>Object with the environment variables passed on to the workers</dd>

<dt>waitBeforeShutdown</dt>
<dd>How long to wait after reloading workers to confirm reload was successful. After this time, the old workers will be shut down.</dd>

<dt>waitBeforeForceQuit</dt>
<dd>How long to wait before the cluster manager will force a worker to shutdown after the initial shutdown request</dd>

Signals

While the cluster manager is running, you can send signals.

*To reload workers - start new ones and shut down the old ones.

kill -HUP MASTERPID

*To output to stdout number of workers and their PIDs

kill -USR1 MASTERPID

*To increase running workers to the maximum number set at the start

kill -USR2 MASTERPID

*To attempt graceful shutdown

kill -TERM MASTERPID

NPM Maintainers

The npm module for this library is maintained by:

• Roger Castells
• Viktor Trako
• Dan Jenkins

License

cluster-manager is licensed under the MIT license.