From fe9a14fede8ca98fbfd59f76ad87e8fd25a6c478 Mon Sep 17 00:00:00 2001
From: rajmayank <mayank9856@gmail.com>
Date: Wed, 9 Oct 2019 04:56:23 +0530
Subject: [PATCH] issue-31: Added health check endpoint

---
 src/app.ts                               |  5 ++-
 src/controllers/healthCheckController.ts | 46 ++++++++++++++++++++++++
 src/routes/healthCheckRoutes.ts          | 17 +++++++++
 swagger.json                             | 19 ++++++++++
 4 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 src/controllers/healthCheckController.ts
 create mode 100644 src/routes/healthCheckRoutes.ts

diff --git a/src/app.ts b/src/app.ts
index 004b532..ffc2a34 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -2,8 +2,10 @@ import * as bodyParser from "body-parser";
 import * as express from "express";
 import * as helmet from "helmet";
 import * as swaggerUi from "swagger-ui-express";
+import * as swaggerDocument from "./../swagger.json";
 
 import { fiddleRoutes } from "./routes/fiddleRoutes";
+import { healthCheckRoutes } from "./routes/healthCheckRoutes";
 
 class App {
   public app: express.Application;
@@ -16,8 +18,9 @@ class App {
   private config(): void {
     this.app.use(helmet());
     this.app.use(bodyParser.json()); // parse json from request body
+    this.app.use("/health", healthCheckRoutes);
     this.app.use("/fiddles", fiddleRoutes);
-    // this.app.use("/docs", swaggerUi.serve, swaggerUi.setup(require("../swagger.json")));
+    this.app.use("/docs", swaggerUi.serve, swaggerUi.setup(swaggerDocument));
   }
 }
 
diff --git a/src/controllers/healthCheckController.ts b/src/controllers/healthCheckController.ts
new file mode 100644
index 0000000..7fc2af8
--- /dev/null
+++ b/src/controllers/healthCheckController.ts
@@ -0,0 +1,46 @@
+import { Request, Response } from "express";
+import * as mongoose from "mongoose";
+
+
+const mongooseConnectionStates = {
+    0: "disconnected",
+    1: "connected",
+    2: "connecting",
+    3: "disconnecting"
+}
+
+export class HealthCheckController {
+
+    public check = (req: Request, res: Response) => {
+
+        let isServerHealthy = true
+
+        let mongooseState = mongoose.connection.readyState;
+        if (mongooseState != 1)
+            isServerHealthy = false
+
+        // Add additional checks here
+
+        let healthStatus = {
+          'status': isServerHealthy ? 'healthy' : 'unhealthy',
+          'services': {
+            'db_connection': mongooseConnectionStates[mongooseState]
+          }
+        }
+
+        if (isServerHealthy) {
+            return res
+                .status(200)
+                .type('json')
+                .send(healthStatus)
+        } else {
+            return res
+                .status(500)
+                .type('json')
+                .send(healthStatus)
+        }
+    };
+
+}
+
+export const healthCheckController = new HealthCheckController();
\ No newline at end of file
diff --git a/src/routes/healthCheckRoutes.ts b/src/routes/healthCheckRoutes.ts
new file mode 100644
index 0000000..3c629a1
--- /dev/null
+++ b/src/routes/healthCheckRoutes.ts
@@ -0,0 +1,17 @@
+import * as express from "express";
+import { healthCheckController } from "../controllers/healthCheckController";
+
+class HealthCheckRoutes {
+  public router: express.Router = express.Router();
+
+  constructor() {
+    this.config();
+  }
+
+  private config(): void {
+
+    this.router.get("/", healthCheckController.check);
+  }
+}
+
+export const healthCheckRoutes = new HealthCheckRoutes().router;
diff --git a/swagger.json b/swagger.json
index f739868..1e1e745 100644
--- a/swagger.json
+++ b/swagger.json
@@ -26,6 +26,25 @@
     }
   },
   "paths": {
+    "/health": {
+      "get": {
+        "tags": [
+          "health"
+        ],
+        "summary": "Get the status of the service",
+        "produces": [
+          "application/json"
+        ],
+        "responses": {
+          "200": {
+            "description": "Service is operating normally"
+          },
+          "500": {
+            "description": "Service is not operating normally"
+          }
+        }
+      }
+    },
     "/users": {
       "post": {
         "tags": [