Add database health check

Directory.Packages.props

@@ -3,42 +3,44 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
   <ItemGroup>
-    <PackageVersion Include="Azure.Search.Documents" Version="11.4.0" />
-    <PackageVersion Include="Azure.Storage.Blobs" Version="12.18.0" />
-    <PackageVersion Include="McMaster.Extensions.CommandLineUtils" Version="4.1.0" />
-    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation" Version="8.0.2" />
-    <PackageVersion Include="Microsoft.Azure.Cosmos" Version="3.36.0" />
-    <PackageVersion Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.2" />
-    <PackageVersion Include="Microsoft.EntityFrameworkCore.Relational" Version="8.0.2" />
+    <PackageVersion Include="Azure.Search.Documents" Version="11.5.1" />
+    <PackageVersion Include="Azure.Storage.Blobs" Version="12.19.1" />
+    <PackageVersion Include="McMaster.Extensions.CommandLineUtils" Version="4.1.1" />
+    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation" Version="8.0.3" />
+    <PackageVersion Include="Microsoft.Azure.Cosmos" Version="3.38.1" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore.Design" Version="8.0.3" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore.Relational" Version="8.0.3" />
     <PackageVersion Include="Microsoft.Extensions.Configuration.Abstractions" Version="8.0.0" />
-    <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.0" />
-    <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.0" />
+    <PackageVersion Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="8.0.1" />
+    <PackageVersion Include="Microsoft.Extensions.Diagnostics.HealthChecks" Version="8.0.3" />
+    <PackageVersion Include="Microsoft.Extensions.Diagnostics.HealthChecks.EntityFrameworkCore" Version="8.0.3" />
+    <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="8.0.1" />
     <PackageVersion Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="8.0.0" />
     <PackageVersion Include="NuGet.Frameworks" Version="6.9.1" />
     <PackageVersion Include="NuGet.Protocol" Version="6.9.1" />
     <PackageVersion Include="NuGet.Versioning" Version="6.9.1" />
     <PackageVersion Include="System.Reflection.Metadata" Version="8.0.0" />
-    <PackageVersion Include="System.Text.Json" Version="8.0.2" />
+    <PackageVersion Include="System.Text.Json" Version="8.0.3" />
     <PackageVersion Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
     <PackageVersion Include="Moq" Version="4.20.70" />
     <PackageVersion Include="xunit" Version="2.7.0" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.7" />
-    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.2" />
-    <PackageVersion Include="coverlet.collector" Version="6.0.1" />
+    <PackageVersion Include="Microsoft.AspNetCore.Mvc.Testing" Version="8.0.3" />
+    <PackageVersion Include="coverlet.collector" Version="6.0.2" />
     <PackageVersion Include="Humanizer" Version="2.14.1" />
-    <PackageVersion Include="Markdig" Version="0.35.0" />
-    <PackageVersion Include="Microsoft.EntityFrameworkCore.SqlServer" Version="8.0.2" />
+    <PackageVersion Include="Markdig" Version="0.36.2" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore.SqlServer" Version="8.0.3" />
     <PackageVersion Include="Microsoft.Data.SqlClient" Version="5.2.0" />
     <PackageVersion Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="8.0.2" />
-    <PackageVersion Include="Pomelo.EntityFrameworkCore.MySql" Version="8.0.1" />
+    <PackageVersion Include="Pomelo.EntityFrameworkCore.MySql" Version="8.0.2" />
     <PackageVersion Include="Aliyun.OSS.SDK.NetCore" Version="2.13.0" />
-    <PackageVersion Include="AWSSDK.S3" Version="3.7.305.29" />
-    <PackageVersion Include="AWSSDK.SecurityToken" Version="3.7.300.54" />
+    <PackageVersion Include="AWSSDK.S3" Version="3.7.307" />
+    <PackageVersion Include="AWSSDK.SecurityToken" Version="3.7.300.60" />
     <PackageVersion Include="Microsoft.Azure.Cosmos.Table" Version="1.0.8" />
     <PackageVersion Include="Microsoft.Azure.Search" Version="10.1.0" />
     <PackageVersion Include="Microsoft.Azure.Storage.Blob" Version="11.2.3" />
-    <PackageVersion Include="Google.Cloud.Storage.V1" Version="4.8.0" />
-    <PackageVersion Include="Microsoft.EntityFrameworkCore.Sqlite" Version="8.0.2" />
+    <PackageVersion Include="Google.Cloud.Storage.V1" Version="4.9.0" />
+    <PackageVersion Include="Microsoft.EntityFrameworkCore.Sqlite" Version="8.0.3" />
   </ItemGroup>
 </Project>

docs/docs/configuration.md

@@ -172,16 +172,27 @@ If not specified, the `MaxRequestBodySize` in BaGetter defaults to 250MB (262144
 
 ## Health Endpoint
 
-When running within a containerized environment like Kubernetes, a basic health endpoint is exposed at `/health` that returns 200 OK and the text "Healthy" when running.
+A health endpoint is exposed at `/health` that returns 200 OK or 503 Service Unavailable and always includes a json object listing the current status of the application:
 
-This path is configurable if needed:
+```json
+{
+  "Status": "Healthy",
+  "Sqlite": "Healthy",
+  ...
+}
+```
+
+The services can be omitted by setting the `Statistics:ListConfiguredServices` to false, in which case only the `Status` property is returned in the json object.
+
+This path and the name of the "Status" property are configurable if needed:
 
 ```json
 {
     ...
 
     "HealthCheck": {
-        "Path": "/healthz"
+        "Path": "/healthz",
+        "StatusPropertyName": "Status"
     },
 
     ...

src/BaGetter.Core/BaGetter.Core.csproj

@@ -10,6 +10,8 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Abstractions" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" />
+    <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks" />
+    <PackageReference Include="Microsoft.Extensions.Diagnostics.HealthChecks.EntityFrameworkCore" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" />
     <PackageReference Include="NuGet.Protocol" />
     <PackageReference Include="System.Reflection.Metadata" />

src/BaGetter.Core/Configuration/HealthCheckOptions.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 
 namespace BaGetter.Core;
@@ -8,6 +8,11 @@ public class HealthCheckOptions : IValidatableObject
     [Required]
     public string Path { get; set; }
 
+    /// <summary>
+    /// What the overall status property is called in the health check response. Default is "Status".
+    /// </summary>
+    public string StatusPropertyName { get; set; } = "Status";
+
     public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
     {
         if (! Path.StartsWith('/'))

src/BaGetter.Core/Extensions/DependencyInjectionExtensions.Providers.cs

@@ -106,6 +106,9 @@ public static IServiceCollection AddBaGetDbContextProvider<TContext>(
             return provider.GetRequiredService<DatabaseSearchService>();
         });
 
+        services.AddHealthChecks()
+            .AddDbContextCheck<TContext>(databaseType, tags: [databaseType]);
+
         return services;
     }
 

src/BaGetter.Core/Extensions/HealthCheckExtensions.cs

@@ -0,0 +1,61 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+
+namespace BaGetter.Core.Extensions;
+
+public static class HealthCheckExtensions
+{
+    private static readonly JsonSerializerOptions SerializerOptions = new()
+    {
+        WriteIndented = true,
+        Converters = { new JsonStringEnumConverter() }
+    };
+
+    /// <summary>
+    /// Formats the <see cref="HealthReport"/> as JSON and writes it to the specified <see cref="Stream"/>.
+    /// </summary>
+    /// <param name="report">The report to format.</param>
+    /// <param name="stream">A writable stream to write the report to. Will not be closed.</param>
+    /// <param name="detailedReport">Whether to include detailed information about each health check.</param>
+    /// <param name="statusPropertyName">The name of the property that will contain the overall status.</param>
+    /// <param name="cancellationToken"></param>
+    /// <returns>A <see cref="Task"/> completing when the report is completely written to the stream.</returns>
+    public static async Task FormatAsJson(this HealthReport report, Stream stream, bool detailedReport, string statusPropertyName = "Status",
+        CancellationToken cancellationToken = default)
+    {
+        // Always include the overall status.
+        IEnumerable<(string Key, HealthStatus Value)> entries = [(statusPropertyName, report.Status)];
+
+        // Include details if requested.
+        if (detailedReport)
+        {
+            entries = entries.Concat(report.Entries.Select(entry => (entry.Key, entry.Value.Status)));
+        }
+
+        await JsonSerializer.SerializeAsync(
+            stream,
+            entries.ToDictionary(entry => entry.Key, entry => entry.Value),
+            SerializerOptions,
+            cancellationToken);
+    }
+
+    /// <summary>
+    /// Determine whether a health check is configured for BaGetter.
+    /// </summary>
+    /// <param name="check">The <see cref="HealthCheckRegistration"/>.</param>
+    /// <param name="options">The current BaGetter configuration. Will be checked for configured services.</param>
+    /// <returns>A boolean representing whether the given check is configured in this BaGetter instance.</returns>
+    public static bool IsConfigured(this HealthCheckRegistration check, BaGetterOptions options)
+    {
+        return check.Tags.Count == 0 || // General checks
+               check.Tags.Contains(options.Database.Type) || // Database check
+               check.Tags.Contains(options.Storage.Type) || // Storage check
+               check.Tags.Contains(options.Search.Type); // Search check
+    }
+}

src/BaGetter/Startup.cs

@@ -1,5 +1,6 @@
 using System;
 using BaGetter.Core;
+using BaGetter.Core.Extensions;
 using BaGetter.Web;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
@@ -8,18 +9,19 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Options;
+using HealthCheckOptions = Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions;
 
 namespace BaGetter;
 
 public class Startup
 {
+    private IConfiguration Configuration { get; }
+
     public Startup(IConfiguration configuration)
     {
         Configuration = configuration ?? throw new ArgumentNullException(nameof(configuration));
     }
 
-    private IConfiguration Configuration { get; }
-
     public void ConfigureServices(IServiceCollection services)
     {
         services.ConfigureOptions<ValidateBaGetterOptions>();
@@ -94,6 +96,16 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
             baget.MapEndpoints(endpoints);
         });
 
-        app.UseHealthChecks(options.HealthCheck.Path);
+        app.UseHealthChecks(options.HealthCheck.Path,
+            new HealthCheckOptions
+            {
+                ResponseWriter = async (context, report) =>
+                {
+                    await report.FormatAsJson(context.Response.Body, options.Statistics.ListConfiguredServices, options.HealthCheck.StatusPropertyName,
+                        context.RequestAborted);
+                },
+                Predicate = check => check.IsConfigured(options)
+            }
+        );
     }
 }

tests/BaGetter.Tests/Support/BaGetApplication.cs

@@ -12,6 +12,7 @@
 using Microsoft.EntityFrameworkCore.Storage;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
 using Microsoft.Extensions.Logging;
 using Moq;
 using Xunit.Abstractions;
@@ -82,6 +83,8 @@ protected override void ConfigureWebHost(IWebHostBuilder builder)
                     services.AddSingleton(_upstreamClient);
                 }
 
+                services.Configure<HealthCheckServiceOptions>(opts => opts.Registrations.Clear());
+
                 // Setup the integration test database.
                 var provider = services.BuildServiceProvider();
                 var scopeFactory = provider.GetRequiredService<IServiceScopeFactory>();