Add basic health check bagetter#105 (bagetter#106)

* add basic healthcheck feature bagetter#105

* make health endpoint configurable

* documentation

* remove newlines

---------

Co-authored-by: GALLIKER\pafor <[email protected]>

docs/docs/configuration.md

@@ -170,6 +170,24 @@ 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.
+
+This path is configurable if needed:
+
+```json
+{
+    ...
+
+    "HealthCheck": {
+        "Path": "/healthz"
+    },
+
+    ...
+}
+```
+
 ## Load secrets from files
 
 Mostly useful when running containerised (e.g. using Docker, Podman, Kubernetes, etc), the application will look for files named in the same pattern as environment variables under `/run/secrets`.

src/BaGetter.Core/Configuration/BaGetterOptions.cs

@@ -50,4 +50,6 @@ public class BaGetterOptions
     public SearchOptions Search { get; set; }
 
     public MirrorOptions Mirror { get; set; }
+
+    public HealthCheckOptions HealthCheck { get; set; }
 }

src/BaGetter.Core/Configuration/HealthCheckOptions.cs

@@ -0,0 +1,20 @@
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+
+namespace BaGetter.Core;
+
+public class HealthCheckOptions : IValidatableObject
+{
+    [Required]
+    public string Path { get; set; }
+
+    public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+    {
+        if (! Path.StartsWith('/'))
+        {
+            yield return new ValidationResult(
+                $"The {nameof(Path)} needs to start with a /",
+                new[] { nameof(Path) });
+        }
+    }
+}

src/BaGetter.Core/Validation/ValidateStartupOptions.cs

@@ -13,19 +13,22 @@ public class ValidateStartupOptions
     private readonly IOptions<DatabaseOptions> _database;
     private readonly IOptions<StorageOptions> _storage;
     private readonly IOptions<MirrorOptions> _mirror;
+    private readonly IOptions<HealthCheckOptions> _healthCheck;
     private readonly ILogger<ValidateStartupOptions> _logger;
 
     public ValidateStartupOptions(
         IOptions<BaGetterOptions> root,
         IOptions<DatabaseOptions> database,
         IOptions<StorageOptions> storage,
         IOptions<MirrorOptions> mirror,
+        IOptions<HealthCheckOptions> healthCheck,
         ILogger<ValidateStartupOptions> logger)
     {
         _root = root ?? throw new ArgumentNullException(nameof(root));
         _database = database ?? throw new ArgumentNullException(nameof(database));
         _storage = storage ?? throw new ArgumentNullException(nameof(storage));
         _mirror = mirror ?? throw new ArgumentNullException(nameof(mirror));
+        _healthCheck = healthCheck ?? throw new ArgumentNullException(nameof(healthCheck));
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
     }
 
@@ -39,6 +42,7 @@ public bool Validate()
             _ = _database.Value;
             _ = _storage.Value;
             _ = _mirror.Value;
+            _ = _healthCheck.Value;
 
             return true;
         }

src/BaGetter/Startup.cs

@@ -40,6 +40,8 @@ public void ConfigureServices(IServiceCollection services)
 
         services.AddSingleton<IConfigureOptions<MvcRazorRuntimeCompilationOptions>, ConfigureRazorRuntimeCompilation>();
 
+        services.AddHealthChecks();
+
         services.AddCors();
     }
 
@@ -89,5 +91,7 @@ public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
 
             baget.MapEndpoints(endpoints);
         });
+
+        app.UseHealthChecks(options.HealthCheck.Path);
     }
 }

src/BaGetter/appsettings.json

@@ -48,5 +48,9 @@
         "Default": "Warning"
       }
     }
+  },
+
+  "HealthCheck": {
+    "Path" : "/health"
   }
 }