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:

1. options.order was specified.
2. 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|