Add Redis Health Check (OrchardCMS#13589)

Co-authored-by: Zoltán Lehóczky <zoltan.lehoczky@lombiq.com>

src/OrchardCore.Modules/OrchardCore.Redis/HealthChecks/Extensions/RedisHealthCheckExtensions.cs

@@ -0,0 +1,9 @@
+using OrchardCore.Redis.HealthChecks;
+
+namespace Microsoft.Extensions.DependencyInjection;
+
+public static class RedisHealthCheckExtensions
+{
+    public static IHealthChecksBuilder AddRedisCheck(this IHealthChecksBuilder healthChecksBuilder)
+        => healthChecksBuilder.AddCheck<RedisHealthCheck>("Redis Health Check");
+}

src/OrchardCore.Modules/OrchardCore.Redis/HealthChecks/RedisHealthCheck.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+
+namespace OrchardCore.Redis.HealthChecks;
+
+public class RedisHealthCheck : IHealthCheck
+{
+    private const int Timeout = 30;
+
+    private readonly IServiceProvider _serviceProvider;
+
+    public RedisHealthCheck(IServiceProvider serviceProvider) => _serviceProvider = serviceProvider;
+
+    public async Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var redisService = _serviceProvider.GetService<IRedisService>();
+            if (redisService == null)
+            {
+                return HealthCheckResult.Unhealthy(description: $"The service '{nameof(IRedisService)}' isn't registered.");
+            }
+
+            if (redisService.Connection == null)
+            {
+                await redisService.ConnectAsync();
+            }
+
+            if (redisService.Connection.IsConnected)
+            {
+                var time = await redisService.Database.PingAsync();
+                if (time > TimeSpan.FromSeconds(Timeout))
+                {
+                    return HealthCheckResult.Unhealthy(description: $"The Redis server couldn't be reached within {Timeout} seconds and might be offline or have degraded performance.");
+                }
+                else
+                {
+                    return HealthCheckResult.Healthy();
+                }
+            }
+            else
+            {
+                return HealthCheckResult.Unhealthy(description: "Couldn't connect to the Redis server.");
+            }
+        }
+        catch (Exception ex)
+        {
+            return HealthCheckResult.Unhealthy("Retrieving the status of the Redis service failed.", ex);
+        }
+    }
+}

src/OrchardCore.Modules/OrchardCore.Redis/HealthChecks/Startup.cs

@@ -0,0 +1,19 @@
+using Microsoft.Extensions.DependencyInjection;
+using OrchardCore.Modules;
+
+namespace OrchardCore.Redis.HealthChecks;
+
+[RequireFeatures("OrchardCore.HealthChecks")]
+public class Startup : StartupBase
+{
+    // The order of this startup configuration should be greater than zero to register the Redis check early,
+    // so the health check can be reported alongside with other health checks in the system.
+    public override int Order => 100;
+
+    public override void ConfigureServices(IServiceCollection services)
+    {
+        services
+            .AddHealthChecks()
+            .AddRedisCheck();
+    }
+}

src/docs/reference/modules/Redis/README.md

@@ -8,6 +8,10 @@ Integrates Redis into Orchard Core. Provides the following features:
 - Redis Lock: Distributed Lock using Redis.
 - Redis DataProtection: Distributed DataProtection using Redis.
 
+## Health Checks
+
+This module provides a health check to report the status for the Redis server. Refer also to the [Health Checks Section](../HealthChecks/README.md).
+
 ## Video
 
 <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/etH6IJOGUe8" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>