add health check

tanks-backend/TanksServer/Endpoints.cs

@@ -1,7 +1,12 @@
+using System.IO;
+using System.Text;
+using System.Text.Json;
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Diagnostics.HealthChecks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.HttpResults;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
 using TanksServer.GameLogic;
 using TanksServer.Interactivity;
 
@@ -25,6 +30,11 @@ internal sealed class Endpoints(
         app.MapGet("/map", () => mapService.MapNames);
         app.MapPost("/map", PostMap);
         app.MapGet("/map/{name}", GetMapByName);
+
+        app.MapHealthChecks("/health", new HealthCheckOptions
+        {
+            ResponseWriter = WriteJsonHealthCheckResponse
+        });
     }
 
     private Results<BadRequest<string>, NotFound<string>, Ok> PostMap([FromQuery] string name)
@@ -107,4 +117,41 @@ internal sealed class Endpoints(
         var mapInfo = new MapInfo(prototype.Name, prototype.GetType().Name, preview.Data);
         return TypedResults.Ok(mapInfo);
     }
+
+    private static Task WriteJsonHealthCheckResponse(HttpContext context, HealthReport healthReport)
+    {
+        context.Response.ContentType = "application/json; charset=utf-8";
+
+        var options = new JsonWriterOptions { Indented = true };
+
+        using var memoryStream = new MemoryStream();
+        using (var jsonWriter = new Utf8JsonWriter(memoryStream, options))
+        {
+            jsonWriter.WriteStartObject();
+            jsonWriter.WriteString("status", healthReport.Status.ToString());
+            jsonWriter.WriteStartObject("results");
+
+            foreach (var healthReportEntry in healthReport.Entries)
+            {
+                jsonWriter.WriteStartObject(healthReportEntry.Key);
+                jsonWriter.WriteString("status",
+                    healthReportEntry.Value.Status.ToString());
+                jsonWriter.WriteString("description",
+                    healthReportEntry.Value.Description);
+                jsonWriter.WriteStartObject("data");
+
+                foreach (var item in healthReportEntry.Value.Data)
+                    jsonWriter.WriteString(item.Key, item.Value.ToString());
+
+                jsonWriter.WriteEndObject();
+                jsonWriter.WriteEndObject();
+            }
+
+            jsonWriter.WriteEndObject();
+            jsonWriter.WriteEndObject();
+        }
+
+        return context.Response.WriteAsync(
+            Encoding.UTF8.GetString(memoryStream.ToArray()));
+    }
 }