Satan-pm NPM | npm.io

satan-pm

Upstart friendly node.js cluster manager.

Usage

  Usage: satan [options] -- [args...]

  Options:

    -h, --help                      output usage information
    -V, --version                   output the version number
    -s, --script [path]             worker script path
    -d, --working-directory [path]  working directory
    -i, --instances [count]         number of workers to spawn
    -n, --node-arguments [args]     custom arguments to nodejs
    -p, --scheduling-policy         cluster scheduling policy(none or rr)
    -c, --config [path]             config file path
    -p, --pid-file [path]           pid file path

Graceful Reload

When satan-pm process receives a SIGHUP signal, it will gracefully reload all workers, each at a time.

To do so, it will trigger a disconnect on the worker with cluster.worker.disconnect().

You can hook up the shutdown process to do a custom cleanup procedure(e.g.: you have a worker consuming a Redis queue). For this you need to add a listener to the shutdown event on the process global.

Please note that when you listen to the shutdown event you are responsible for terminating the process(i.e.: calling cluster.worker.disconnect()).

Graceful Shutdown

satan-pm will also do a graceful shutdown when it receives a SIGTERM or SIGINT signal. The behaviour is exactly the same as the graceful reload.

Example

config.json

{
	"workingDirectory": "/app/your-server/current",
	"script": "bin/server.js",
	"arguments": "-p 3000",
	"instances": 4
}

Running:

satan -c config.json

Bonus: GC Signal

When satan-pm receives a SIGUSR2 it will trigger a garbage collection. This is useful when debugging memory leaks or when you need to clean up the memory before a reload.

Bonus: Upstart Configuration

This is a example upstart configuration that plays well with satan:

start on started networking
stop on stopping networking

respawn
respawn limit 5 20

reload signal SIGHUP

chdir /app/your-server/current

setuid deploy
setgid deploy

env NODE_ENV=production

exec /usr/bin/satan -c /app/your-server/shared/satan.json