@webframe/healthcheck

A healthcheck for services with no HTTP server, such as queue workers. It writes the service's health to a file every so often, and the container's healthcheck reads it.

npm install @webframe/healthcheck

import { defineHealthcheck } from '@webframe/healthcheck'

const worker = defineWorker({
  source,
  jobs,
  health: defineHealthcheck({ filePath: '/tmp/health', checkInterval: 10_000 }),
})

A worker given it marks it unhealthy when it hits an error it can't recover from, so the container is restarted. Anything else can call health.error() itself.

# compose.yaml
healthcheck:
  test: ["CMD", "grep", "-q", "^healthy$", "/tmp/health"]
  interval: 30s

Services with an HTTP server don't need it: every server answers GET /healthcheck.

Options

Option
filePath	The file to write healthy or unhealthy to.
checkInterval	How often to write it, in milliseconds.

It writes the file once straight away, then on each interval. The timer doesn't keep the process alive by itself.

Methods

Name	What it does
error()	Marks the service unhealthy for good, writes that at once, and stops the timer.
read()	The status in the file. If the file holds anything else, it marks the service unhealthy and throws.
stop()	Stops writing, as the service shuts down.