node-healthz

Define a set of checkers to your express application. /healthz endpoint then becomes available.

router.use(
    expressMiddleware(
        {
            sql: {
                type: 'knex',
                adapter: knex, // Your knex instance
            },
            mongo: {
                type: 'mongoose',
                adapter: mongoose, // Your mongoose instance
            },
            custom: {
                check: () => true,/* Custom check. May be async */
            }
        }
    )
)

..and resulting GET /healthz resopnse:

{
    "tldr": "OK",
    "t": "501ms",
    "checkers": {
        "sql": {
            "result": true,
            "error": null,
            "t": "0ms",
            "health": "OK",
            "crucial": false
        },
        "hello": {
            "result": null,
            "error": null,
            "t": "501ms",
            "health": "TIMEOUT",
            "crucial": false
        },
    },
    "options": {
        "timeout": 500
    }
}

API

expressMiddleware({ [key: string]: AdapterOptions }): RequestHandler

Define a set of app health checkers. Returns an express route handler.

System is considered healthy if all the checkers responded without error in given timeout.

If request comes, and routes starts /healthz, system health is calculated and returned:

GET /healthz

Supported query parameters
timeout	Optional. Default: 5000. How much time in ms do the checkers have to respond.

Status code is 500 for unhealthy system, 200 otherwise.

Response JSON body:

{
    tldr: 'OK' | 'NOT_OK',
    checkers: [
        {
            result: boolean // true if checker responds in given time
            error: string | null // error message if the checker fails
            t: string // time, 245ms
            health: 'OK' | 'ERROR' | 'TIMEOUT'
            crucial: boolean
        }
    ],
    t: string // total time, 245ms
    options: { // Optional parameters from the input
        timeout: 1000,
    }
}

Types

AdapterOptions: object

Attribute	Type	Description
type	AdapterType	Optional. If not supplied, check function has to be defined.
adapter	any	Optional. If type is specified, appropriate adapter instance has to be passed in here. E.g. you Mongoose instance.
crucial	boolean	Optional. Default: false. If true and checker fails, system health outcome cannot be OK.
check	function	Optional. Use this if you want to do the check completely by yourself. Check may return a Promise. Check is called with AdapterOptions, extended with a timeout: number prop.

AdapterType: string

Supported adapter types defining the instance that is found in adapter option.

'knex' | 'mongoose'