Add hardcoded healt check functionality

Author: ivanvs

examples/test-status-monitor/src/app.module.ts

@@ -2,10 +2,11 @@ import { Module } from '@nestjs/common';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
 import { StatusMonitorModule } from '../../../dist/status.monitor.module';
+import { HealtController } from './healtController';
 
 @Module({
   imports: [StatusMonitorModule],
-  controllers: [AppController],
+  controllers: [AppController, HealtController],
   providers: [AppService],
 })
 export class AppModule {}

examples/test-status-monitor/src/healtController.ts

@@ -0,0 +1,16 @@
+import { Get, Controller, HttpCode } from '@nestjs/common';
+
+@Controller('healt')
+export class HealtController {
+  @Get('alive')
+  @HttpCode(200)
+  alive(): string {
+    return 'OK';
+  }
+
+  @Get('dead')
+  @HttpCode(500)
+  dead(): string {
+    return 'DEAD';
+  }
+}

package-lock.json

@@ -28,6 +28,7 @@
   },
   "dependencies": {
     "@nestjs/websockets": "^5.4.0",
+    "axios": "^0.18.0",
     "debug": "^2.6.8",
     "handlebars": "~4.0.12",
     "on-headers": "^1.0.1",

package.json

@@ -0,0 +1,75 @@
+import { Injectable, Inject, forwardRef } from '@nestjs/common';
+import axios from 'axios';
+
+@Injectable()
+export class HealtCheckService {
+  healthChecks = [
+    {
+      protocol: 'http',
+      host: 'localhost',
+      path: '/healt/alive',
+      port: '3001',
+    },
+    {
+      protocol: 'http',
+      host: 'localhost',
+      path: '/healt/dead',
+      port: '3001',
+    },
+  ];
+
+  checkAllEndpoints() {
+    const checkPromises = [];
+
+    this.healthChecks.forEach(healthCheck => {
+      checkPromises.push(this.checkEndpoint(healthCheck));
+    });
+
+    let checkResults = [];
+
+    return this.allSettled(checkPromises).then(results => {
+      results.forEach((result, index) => {
+        if (result.state === 'rejected') {
+          checkResults.push({
+            path: this.healthChecks[index].path,
+            status: 'failed',
+          });
+        } else {
+          checkResults.push({
+            path: this.healthChecks[index].path,
+            status: 'ok',
+          });
+        }
+      });
+
+      return checkResults;
+    });
+  }
+
+  private checkEndpoint(healthCheck): Promise<any> {
+    let uri = `${healthCheck.protocol}://${healthCheck.host}`;
+
+    if (healthCheck.port) {
+      uri += `:${healthCheck.port}`;
+    }
+
+    uri += healthCheck.path;
+
+    //TODO (ivasiljevic) use http service instead of axios
+    return axios({
+      url: uri,
+      method: 'GET',
+    });
+  }
+
+  private allSettled(promises: Promise<any>[]): Promise<any> {
+    let wrappedPromises = promises.map(p =>
+      Promise.resolve(p).then(
+        val => ({ state: 'fulfilled', value: val }),
+        err => ({ state: 'rejected', value: err }),
+      ),
+    );
+
+    return Promise.all(wrappedPromises);
+  }
+}

src/healt.check.service.ts

@@ -2,6 +2,7 @@ import { Get, Controller, HttpCode } from '@nestjs/common';
 import * as fs from 'fs';
 import * as path from 'path';
 import Handlebars from 'handlebars';
+import { HealtCheckService } from './healt.check.service';
 
 const controllerPath = 'monitor';
 
@@ -10,7 +11,7 @@ export class StatusMonitorController {
   data;
   render;
 
-  constructor() {
+  constructor(private readonly healtCheckService: HealtCheckService) {
     this.data = {
       title: 'Nest.js Status',
       port: 3001,
@@ -32,7 +33,9 @@ export class StatusMonitorController {
 
   @Get()
   @HttpCode(200)
-  root() {
+  async root() {
+    const healtData = await this.healtCheckService.checkAllEndpoints();
+    this.data.healthCheckResults = healtData;
     return this.render(this.data);
   }
 }

src/status.monitor.controller.ts

@@ -3,10 +3,11 @@ import { StatusMonitorController } from './status.monitor.controller';
 import { StatusMonitorGateway } from './status.monitor.gateway';
 import { StatusMonitoringService } from './status.monitoring.service';
 import { StatusMonitorMiddleware } from './status.monitor.middleware';
+import { HealtCheckService } from './healt.check.service';
 
 @Module({
   controllers: [StatusMonitorController],
-  providers: [StatusMonitorGateway, StatusMonitoringService],
+  providers: [StatusMonitorGateway, StatusMonitoringService, HealtCheckService],
 })
 export class StatusMonitorModule {
   configure(consumer: MiddlewareConsumer) {

src/status.monitor.module.ts

@@ -94,7 +94,6 @@ export class StatusMonitoringService {
     const responseTime = (diff[0] * 1e3 + diff[1]) * 1e-6;
     const category = Math.floor(statusCode / 100);
 
-    console.log(responseTime);
     this.spans.forEach(span => {
       const last = span.responses[span.responses.length - 1];