Roll Call

A module to provide upstream dependency checks for service health endpoints

Requirements

This module is written with standards ES2015 and up and does not use any transpilers.
The required NodeJS engine is >8.6.

Usage

The module should work with any web framework.

const rc = require('@frontseed/roll-call')

const checks = rc.configure({
  // Check a simple HTTP endpoint if it returns 200.
  mySimpleWebCheck: new rc.WebCheck('https://example.com/status'),

  // Add options and a custom callback to execute your own response checks.
  myComplexWebCheck: new rc.WebCheck(
    // URL to check.
    'https://example.com/other',
    // Options passed to the underlying Axios web client.
    {
      validateStatus: () => true,
      timeout: 5000
    },
    // Callback to run on response.
    res => (res && !res.error ? rc.up() : rc.down(res))
  ),

  // Add a raw check to check on any custom dependency such as a socket connection.
  myRawCheck: new RawCheck(() => {
    const result = myInternalCheck()
    return result ? rc.up() : rc.down()
  })
})

The configure() method here returns a function which returns a Promise.
This promise resolves to a an object containing a status code and a JSON payload to serve in a health endpoint payload with a web framework of your choice. Add your own handler to cater for this.

Credits

This is a simplified, more modern and framework agnostic variant of @hmcts/nodejs-healthcheck.