Add health check endpoint

src/common/errors.js

@@ -54,10 +54,19 @@ class ForbiddenError extends ApiError {
   }
 }
 
+// The forbidden error
+class ServiceUnavailable extends ApiError {
+  constructor(message, details) {
+    super(503, 'SERVICE_UNAVAILABLE', message);
+    this.details = details;
+  }
+}
+
 module.exports = {
   ApiError,
   ValidationError,
   NotFoundError,
   UnauthorizedError,
   ForbiddenError,
+  ServiceUnavailable,
 };

src/config.js

@@ -54,7 +54,8 @@ module.exports = {
     AWS_ACCESS_KEY_ID: process.env.AWS_ACCESS_KEY_ID,
     AWS_SECRET_ACCESS_KEY: process.env.AWS_SECRET_ACCESS_KEY,
     AWS_REGION: process.env.AWS_REGION,
-    IS_LOCAL: process.env.IS_LOCAL
+    IS_LOCAL: process.env.IS_LOCAL,
+    TIMEOUT: process.env.TIMEOUT || 10000, // eslint-disable-line no-magic-numbers
   },
   TOPCODER_VALUES: {
     dev: {

src/controllers/AppHealthController.js

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2019 TopCoder, Inc. All rights reserved.
+ */
+
+/**
+ * This controller exposes application health related endpoints.
+ *
+ * @author Thomas Kranitsas
+ * @version 1.0
+ */
+const helper = require('../common/helper');
+const AppHealthService = require('../services/AppHealthService');
+
+/**
+ * gets the application health
+ * @returns {Object} the health details
+ */
+async function getAppHealth() {
+  return await AppHealthService.getAppHealth();
+}
+
+module.exports = {
+  getAppHealth,
+};
+
+helper.buildController(module.exports);

src/models/index.js

@@ -33,4 +33,6 @@ fs.readdirSync(__dirname).forEach((file) => { // eslint-disable-line no-sync
   }
 });
 
+models.DynamoDB = dynamoose.ddb();
+
 module.exports = models;

src/routes.js

@@ -226,4 +226,10 @@ module.exports = {
       method: 'getAppConfig',
     },
   },
+  '/health': {
+    get: {
+      controller: 'AppHealthController',
+      method: 'getAppHealth',
+    },
+  },
 };

src/services/AppHealthService.js

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2019 TopCoder, Inc. All rights reserved.
+ */
+
+/**
+ * This service will provide app health related operations.
+ *
+ * @author Thomas Kranitsas
+ * @version 1.0
+ */
+const config = require('../config');
+const helper = require('../common/helper');
+const { DynamoDB } = require('../models');
+
+/**
+ * gets the application health
+ * @returns {Object} the health details
+ */
+async function getAppHealth() {
+  const checkDynamoDB = new Promise((resolve, reject) => {
+    DynamoDB.listTables({}, (err, data) => {
+      if (err) {
+        return reject(new errors.ServiceUnavailable('DynamoDB instance cannot be reached'));
+      }
+      return resolve();
+    });
+  });
+
+  const timeOutBreak = new Promise((resolve, reject) => {
+    setTimeout(reject, config.DYNAMODB.TIMEOUT, new errors.ServiceUnavailable('DynamoDB instance cannot be reached'));
+  });
+
+  await Promise.race([checkDynamoDB, timeOutBreak]);
+
+  return {
+    checksRun: 1,
+  };
+}
+
+module.exports = {
+  getAppHealth,
+};
+
+helper.buildService(module.exports);