Add health check

Author: ThomasKranitsas

README.md

@@ -47,6 +47,7 @@ The following parameters can be set in config files or in env variables:
 - EMAIL_VERIFY_DISAGREE_URL: email verify disagree URL
 - SCOPES: the configurable M2M token scopes, refer `config/default.js` for more details
 - SEARCH_MEMBERS_ADMIN_ONLY_FIELDS: only admin and M2M can view these fields for search members API
+- HEALTH_CHECK_TIMEOUT: health check timeout in milliseconds
 
 Set the following environment variables used by bus API to get TC M2M token (use 'set' insted of 'export' for Windows OS):
 ```

config/default.js

@@ -43,6 +43,9 @@ module.exports = {
     MEMBER_TRAIT_ES_TYPE: process.env.MEMBER_TRAIT_ES_TYPE || '_doc'
   },
 
+  // health check timeout in milliseconds
+  HEALTH_CHECK_TIMEOUT: process.env.HEALTH_CHECK_TIMEOUT || 3000,
+
   // file upload max size in bytes
   FILE_UPLOAD_SIZE_LIMIT: process.env.FILE_UPLOAD_SIZE_LIMIT
     ? Number(process.env.FILE_UPLOAD_SIZE_LIMIT) : 10 * 1024 * 1024, // 10M

src/common/errors.js

@@ -34,5 +34,6 @@ module.exports = {
   BadRequestError: createError('BadRequestError', 400),
   UnauthorizedError: createError('UnauthorizedError', 401),
   ForbiddenError: createError('ForbiddenError', 403),
-  NotFoundError: createError('NotFoundError', 404)
+  NotFoundError: createError('NotFoundError', 404),
+  ServiceUnavailableError: createError('ServiceUnavailableError', 503)
 }

src/controllers/HealthController.js

@@ -0,0 +1,35 @@
+/**
+ * Controller for health check endpoint
+ */
+const config = require('config')
+const service = require('../services/SearchService')
+const errors = require('../common/errors')
+
+// the topcoder-healthcheck-dropin library returns checksRun count,
+// here it follows that to return such count
+let checksRun = 0
+
+/**
+ * Check health of the app
+ * @param {Object} req the request
+ * @param {Object} res the response
+ */
+async function checkHealth (req, res) {
+  // perform a quick database access operation, if there is no error and is quick, then consider it healthy
+  checksRun += 1
+  const timestampMS = new Date().getTime()
+  try {
+    await service.searchMembers(null, { page: 1, perPage: 1 })
+  } catch (e) {
+    throw new errors.ServiceUnavailableError(`There is database operation error, ${e.message}`)
+  }
+  if (new Date().getTime() - timestampMS > Number(config.HEALTH_CHECK_TIMEOUT)) {
+    throw new errors.ServiceUnavailableError('Database operation is slow.')
+  }
+  // there is no error, and it is quick, then return checks run count
+  res.send({ checksRun })
+}
+
+module.exports = {
+  checkHealth
+}

src/routes.js

@@ -108,5 +108,11 @@ module.exports = {
       method: 'searchMembers',
       scopes: [MEMBERS.READ, MEMBERS.ALL]
     }
+  },
+  '/members/health': {
+    get: {
+      controller: 'HealthController',
+      method: 'checkHealth'
+    }
   }
 }