feat(status): Custom status response (#192)

* Added statusOkResponse to configuration

The new configuration property: statusOkResponse will allow to globally configure the HTTP response body, used to respond with on a successful healthcheck.

* Memoize the value of statusOkResponse

When no healthtchecks were defined, the value of statusOkResponse would be returned as is. Therefore, memoizing its string representation would boost performance.

* Added statusErrorResponse to configuration

The new configuration property: statusErrorResponse will allow to globally configure the HTTP response body, used to respond with on an unsuccessful healthcheck.
An unsuccessful healthcheck may override the global statusErrorResponse property by setting the statusResponse property on the Error object.

* Incorporated use of headers

README.md

@@ -58,7 +58,9 @@ const options = {
   caseInsensitive,                  // [optional] whether given health checks routes are case insensitive (defaults to false)
 
   statusOk,                         // [optional = 200] status to be returned for successful healthchecks
+  statusOkResponse,                 // [optional = { status: 'ok' }] status response to be returned for successful healthchecks
   statusError,                      // [optional = 503] status to be returned for unsuccessful healthchecks
+  statusErrorResponse,              // [optional = { status: 'error' }] status response to be returned for unsuccessful healthchecks
 
   // cleanup options
   timeout: 1000,                    // [optional = 1000] number of milliseconds before forceful exiting

lib/standalone-tests/terminus.onsignal.fail.custom.response.js

@@ -0,0 +1,23 @@
+'use strict'
+const http = require('http')
+const server = http.createServer((req, res) => res.end('hello'))
+
+const { createTerminus } = require('../../')
+const SIGNAL = 'SIGINT'
+
+createTerminus(server, {
+  healthChecks: {
+    '/health': () => Promise.resolve()
+  },
+  signal: SIGNAL,
+  beforeShutdown: () => {
+    return new Promise((resolve) => {
+      setTimeout(resolve, 1000)
+    })
+  },
+  statusErrorResponse: { status: 'down' }
+})
+
+server.listen(8000, () => {
+  process.kill(process.pid, SIGNAL)
+})

lib/standalone-tests/terminus.onsignal.fail.custom.status.code.js

@@ -0,0 +1,23 @@
+'use strict'
+const http = require('http')
+const server = http.createServer((req, res) => res.end('hello'))
+
+const { createTerminus } = require('../../')
+const SIGNAL = 'SIGINT'
+
+createTerminus(server, {
+  healthChecks: {
+    '/health': () => Promise.resolve()
+  },
+  signal: SIGNAL,
+  beforeShutdown: () => {
+    return new Promise((resolve) => {
+      setTimeout(resolve, 1000)
+    })
+  },
+  statusError: 501
+})
+
+server.listen(8000, () => {
+  process.kill(process.pid, SIGNAL)
+})

lib/terminus.js

@@ -3,28 +3,23 @@
 const stoppable = require('stoppable')
 const { promisify } = require('util')
 
-const SUCCESS_RESPONSE = JSON.stringify({
-  status: 'ok'
-})
+let SUCCESS_RESPONSE
 
-const FAILURE_RESPONSE = JSON.stringify({
-  status: 'error'
-})
+let FAILURE_RESPONSE
 
 function noopResolves () {
   return Promise.resolve()
 }
 
-async function sendSuccess (res, { info, verbatim, statusOk, headers }) {
+async function sendSuccess (res, { info, verbatim, statusOk, statusOkResponse, headers }) {
+  res.statusCode = statusOk
   res.setHeader('Content-Type', 'application/json')
   res.writeHead(statusOk, headers)
   if (info) {
     return res.end(
       JSON.stringify(
         Object.assign(
-          {
-            status: 'ok'
-          },
+          statusOkResponse,
           verbatim ? info : { info, details: info }
         )
       )
@@ -34,7 +29,7 @@ async function sendSuccess (res, { info, verbatim, statusOk, headers }) {
 }
 
 async function sendFailure (res, options) {
-  const { error, headers, onSendFailureDuringShutdown, exposeStackTraces, statusCode, statusError } = options
+  const { error, headers, onSendFailureDuringShutdown, exposeStackTraces, statusCode, statusResponse, statusError, statusErrorResponse } = options
 
   function replaceErrors (_, value) {
     if (value instanceof Error) {
@@ -54,16 +49,19 @@ async function sendFailure (res, options) {
   if (onSendFailureDuringShutdown) {
     await onSendFailureDuringShutdown()
   }
+  res.statusCode = statusCode || statusError
+  const responseBody = statusResponse || statusErrorResponse
   res.setHeader('Content-Type', 'application/json')
   res.writeHead(statusCode || statusError, headers)
   if (error) {
-    return res.end(JSON.stringify({
-      status: 'error',
-      error,
-      details: error
-    }, replaceErrors))
+    return res.end(JSON.stringify(
+      Object.assign(
+        responseBody, {
+          error,
+          details: error
+        }), replaceErrors))
   }
-  res.end(FAILURE_RESPONSE)
+  res.end(statusResponse ? JSON.stringify(responseBody) : FAILURE_RESPONSE)
 }
 
 const intialState = {
@@ -73,35 +71,39 @@ const intialState = {
 function noop () {}
 
 function decorateWithHealthCheck (server, state, options) {
-  const { healthChecks, logger, headers, onSendFailureDuringShutdown, sendFailuresDuringShutdown, caseInsensitive, statusOk, statusError } = options
+  const { healthChecks, logger, headers, onSendFailureDuringShutdown, sendFailuresDuringShutdown, caseInsensitive, statusOk, statusOkResponse, statusError, statusErrorResponse } = options
 
   let hasSetHandler = false
   const createHandler = (listener) => {
     const check = hasSetHandler
       ? () => {}
       : async (healthCheck, res) => {
         if (state.isShuttingDown && sendFailuresDuringShutdown) {
-          return sendFailure(res, { onSendFailureDuringShutdown, statusError })
+          return sendFailure(res, { onSendFailureDuringShutdown, statusError, statusErrorResponse })
         }
         let info
         try {
           info = await healthCheck({ state })
         } catch (error) {
           logger('healthcheck failed', error)
+          const statusCode = error.statusCode
+          const statusResponse = error.statusResponse
           return sendFailure(
             res,
             {
               error: error.causes,
               headers,
               exposeStackTraces: healthChecks.__unsafeExposeStackTraces,
-              statusCode: error.statusCode,
-              statusError
+              statusCode,
+              statusResponse,
+              statusError,
+              statusErrorResponse
             }
           )
         }
         return sendSuccess(
           res,
-          { info, verbatim: healthChecks.verbatim, statusOk, headers }
+          { info, verbatim: healthChecks.verbatim, statusOk, statusOkResponse, headers }
         )
       }
 
@@ -184,12 +186,18 @@ function terminus (server, options = {}) {
     logger = noop,
     caseInsensitive = false,
     statusOk = 200,
+    statusOkResponse = { status: 'ok' },
     statusError = 503,
+    statusErrorResponse = { status: 'error' },
     headers = options.headers || {}
   } = options
   const onSignal = options.onSignal || options.onSigterm || noopResolves
   const state = Object.assign({}, intialState)
 
+  SUCCESS_RESPONSE = JSON.stringify(statusOkResponse)
+
+  FAILURE_RESPONSE = JSON.stringify(statusErrorResponse)
+
   if (Object.keys(healthChecks).length > 0) {
     decorateWithHealthCheck(server, state, {
       healthChecks,
@@ -198,7 +206,9 @@ function terminus (server, options = {}) {
       onSendFailureDuringShutdown,
       caseInsensitive,
       statusOk,
+      statusOkResponse,
       statusError,
+      statusErrorResponse,
       headers
     })
   }