Adding API Health Check (#191)

src/Web/HealthChecks/ApiHealthCheck.cs

@@ -0,0 +1,40 @@
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.eShopWeb.Web.HealthChecks
+{
+    public class ApiHealthCheck : IHealthCheck
+    {
+        private readonly IHttpContextAccessor _httpContextAccessor;
+        private readonly LinkGenerator _linkGenerator;
+
+        public ApiHealthCheck(IHttpContextAccessor httpContextAccessor, LinkGenerator linkGenerator)
+        {
+            _httpContextAccessor = httpContextAccessor;
+            _linkGenerator = linkGenerator;
+        }
+
+        public async Task<HealthCheckResult> CheckHealthAsync(
+            HealthCheckContext context,
+            CancellationToken cancellationToken = default(CancellationToken))
+        {
+            var request = _httpContextAccessor.HttpContext.Request;
+
+            string apiLink = _linkGenerator.GetPathByAction("List", "Catalog");
+            string myUrl = request.Scheme + "://" + request.Host.ToString() + apiLink;
+            var client = new HttpClient();
+            var response = await client.GetAsync(myUrl);
+            var pageContents = await response.Content.ReadAsStringAsync();
+            if (pageContents.Contains(".NET Bot Black Sweatshirt"))
+            {
+                return HealthCheckResult.Healthy("The check indicates a healthy result.");
+            }
+
+            return HealthCheckResult.Unhealthy("The check indicates an unhealthy result.");
+        }
+    }
+}

src/Web/HealthChecks/HomePageHealthCheck.cs

@@ -19,7 +19,9 @@ namespace Microsoft.eShopWeb.Web.HealthChecks
             HealthCheckContext context,
             CancellationToken cancellationToken = default(CancellationToken))
         {
-            string myUrl = _httpContextAccessor.HttpContext.Request.Host.ToString();
+            var request = _httpContextAccessor.HttpContext.Request;
+            string myUrl = request.Scheme + "://" + request.Host.ToString();
+
             var client = new HttpClient();
             var response = await client.GetAsync(myUrl);
             var pageContents = await response.Content.ReadAsStringAsync();

src/Web/Properties/launchSettings.json

@@ -1,4 +1,4 @@
-{
+{
   "iisSettings": {
     "windowsAuthentication": false,
     "anonymousAuthentication": true,

src/Web/Startup.cs

@@ -1,4 +1,5 @@
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Diagnostics.HealthChecks;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Identity;
@@ -18,8 +19,12 @@ using Microsoft.eShopWeb.Web.Interfaces;
 using Microsoft.eShopWeb.Web.Services;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using Newtonsoft.Json;
 using Swashbuckle.AspNetCore.Swagger;
 using System;
+using System.Linq;
+using System.Net.Mime;
 using System.Text;
 
 namespace Microsoft.eShopWeb.Web
@@ -121,7 +126,8 @@ namespace Microsoft.eShopWeb.Web
             });
 
             services.AddHealthChecks()
-                .AddCheck<HomePageHealthCheck>("home_page_health_check");
+                .AddCheck<HomePageHealthCheck>("home_page_health_check")
+                .AddCheck<ApiHealthCheck>("api_health_check");
 
             _services = services; // used to debug registered services
         }
@@ -151,7 +157,25 @@ namespace Microsoft.eShopWeb.Web
         public void Configure(IApplicationBuilder app, IHostingEnvironment env, LinkGenerator linkGenerator)
         {
             //app.UseDeveloperExceptionPage();
-            app.UseHealthChecks("/health");
+            app.UseHealthChecks("/health",
+                new HealthCheckOptions
+                {
+                    ResponseWriter = async (context, report) =>
+                    {
+                        var result = JsonConvert.SerializeObject(
+                            new
+                            {
+                                status = report.Status.ToString(),
+                                errors = report.Entries.Select(e => new
+                                {
+                                    key = e.Key,
+                                    value = Enum.GetName(typeof(HealthStatus), e.Value.Status)
+                                })
+                            });
+                        context.Response.ContentType = MediaTypeNames.Application.Json;
+                        await context.Response.WriteAsync(result);
+                    }
+                });
             if (env.IsDevelopment())
             {
                 app.UseDeveloperExceptionPage();