Add health check for website and worker

Author: joelverhagen

deploy/bicep/function-worker.bicep

@@ -130,6 +130,7 @@ resource worker 'Microsoft.Web/sites@2022-09-01' = {
         minTlsVersion: '1.2'
         alwaysOn: !isConsumptionPlan
         use32BitWorkerProcess: false
+        healthCheckPath: '/healthz'
         appSettings: concat([
             {
               name: 'AzureFunctionsJobHost__logging__LogLevel__Default'

deploy/bicep/spot-worker.bicep

@@ -262,7 +262,7 @@ resource vmss 'Microsoft.Compute/virtualMachineScaleSets@2021-11-01' = {
               settings: {
                 protocol: 'http'
                 port: 80
-                requestPath: '/'
+                requestPath: '/healthz'
               }
             }
           }

deploy/bicep/website.bicep

@@ -49,6 +49,7 @@ resource website 'Microsoft.Web/sites@2022-09-01' = {
         minTlsVersion: '1.2'
         alwaysOn: false // I've run into problems with the AAD client certificate not refreshing...
         use32BitWorkerProcess: false
+        healthCheckPath: '/healthz'
         appSettings: concat([
             {
               name: 'AzureAd__Instance'

src/Website/Controllers/HomeController.cs

@@ -26,6 +26,12 @@ public ViewResult Index()
             return View(_options.Value.ShowAdminMetadata ? _cache : null);
         }
 
+        [HttpGet("/healthz")]
+        public ContentResult Health()
+        {
+            return Content("The website is alive.");
+        }
+
         public async Task<RedirectToActionResult> SignOutAndRedirect()
         {
             await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);

src/Worker/Functions.cs

@@ -1,9 +1,11 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Net;
 using System.Threading.Tasks;
 using Azure.Storage.Queues.Models;
 using Microsoft.Azure.Functions.Worker;
+using Microsoft.Azure.Functions.Worker.Http;
 
 namespace NuGet.Insights.Worker
 {
@@ -33,6 +35,16 @@ public Functions(
             _messageProcessor = messageProcessor;
         }
 
+        [Function("HealthFunction")]
+        public HttpResponseData HealthFunction(
+            [HttpTrigger(AuthorizationLevel.Anonymous, "GET", Route = "healthz")] HttpRequestData request)
+        {
+            var response = request.CreateResponse(HttpStatusCode.OK);
+            response.Headers.Add("Content-Type", "text/plain; charset=utf-8");
+            response.WriteString("The worker is alive.");
+            return response;
+        }
+
         [Function("MetricsFunction")]
         public async Task MetricsFunction(
             [TimerTrigger("*/10 * * * * *")] TimerInfo timerInfo)

src/Worker/host.json

@@ -18,6 +18,9 @@
     "queues": {
       "maxDequeueCount": 10,
       "messageEncoding": "none"
+    },
+    "http": {
+      "routePrefix": ""
     }
   }
 }