Shutdown-hook NPM

Shutdown-Hook

Shutdown-Hook is an injectable shutdown hook (well dah..) module for Node.js applications.

Installation

npm install shutdown-hook

Usage

Create a new instance:

const ShutdownHook = require('shutdown-hook')
let shutdownHook = new ShutdownHook(options)

Constructor Options:

Property	Description	Default Value
timeout	Sets a timeout in ms for the shutdown operation to complete. If the shutdown operations exceed the timeout, the process will exit with code 1	10000ms
lifo	Reverses the execution order of the shutdown functions	false

Add shutdown functions:

shutdownHook.add(_ => doSomething(), options)

Shutdown functions are executed in the order they were added unless:

options.order was specified.
lifo: true was specified when instantiating the hook.

Shutdown function can return nothing, a value, a Promise, or throw an error. A rejected promise or error will stop the shutdown sequence (subsequent functions will not be run) and exit the process with code 1.

You can also name shutdown functions:

shutdownHook.add('database', _ => doSomething(), {name: "foo"})

This might be useful when listening to events (see below). If no name was given, the library auto-generates a name for consistency.

Options:

Property	Description	Default Value
name	the name of the shutdown function. will be used when emitting events
order	the order of the function is the shutdown sequence. functions are ordered in ascending order before execution	0

Register to termination signals:

shutdownHook.register()

Registers the shutdown hook to trigger the shutdown sequence when receiving SIGTERM, SIGINT or "shutdown" messages sent through the process event emitter.

Listen to shutdown sequence events:

shutdownHook.on('ShutdownStarted', (e) => log.info('it has began'))
shutdownHook.on('ComponentShutdown', (e) => log.info('shutting down one component'))
shutdownHook.on('ShutdownEnded', (e) => log.info('it has ended'))

Events structure:

Event	Property	Type	Description	Optional
ComponentShutdown	name	String	Name of the shutdown functions that's being executed	No
	order	Number	the order of the shutdown function in the sequence	No
	index	Number	the index of the shutdown function in the sequence	No
ShutdownEnded	code	Number	The exit code the library used when calling `process.exit()`	No
	error	Error	The error the library caught in case the sequence failed to run	Yes