feat: Add system data collection API endpoint

.gitignore

@@ -1,2 +1,3 @@
 /bin
+/data
 /obj

API/Collect.cs

@@ -0,0 +1,40 @@
+using System.Text.Json;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Open_Rails_Telemetry.API
+{
+    [Route("api/[controller]")]
+    [ApiController]
+    public class Collect : ControllerBase
+    {
+        readonly IConfiguration Configuration;
+        readonly string DataPathCollectSystem;
+
+        public Collect(IConfiguration configuration)
+        {
+            Configuration = configuration;
+            DataPathCollectSystem = Path.Combine(Configuration["DataPath"], "collect", "system");
+            if (!Directory.Exists(DataPathCollectSystem)) Directory.CreateDirectory(DataPathCollectSystem);
+        }
+
+        [HttpPost("System")]
+        [Consumes("application/json")]
+        public async Task<IActionResult> PostSystem([FromBody] JsonElement data)
+        {
+            // File's name has the date for analysis, and a random key to prevent collisions
+            var date = DateTime.UtcNow.Date;
+            var randomKey = Guid.NewGuid().ToString();
+            var file = new FileInfo(Path.Combine(DataPathCollectSystem, $"{date:yyyy-MM-dd}_{randomKey}.json"));
+            // Write the JSON into the file
+            await using (var stream = file.Create())
+            {
+                await JsonSerializer.SerializeAsync(stream, data);
+            }
+            // Wipe out the file's timestamps so we cannot correlate them with e.g. access logs
+            file.CreationTimeUtc = date;
+            file.LastWriteTimeUtc = date;
+            file.LastAccessTimeUtc = date;
+            return Ok();
+        }
+    }
+}

Program.cs

@@ -1,6 +1,7 @@
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
+builder.Services.AddControllers();
 builder.Services.AddRazorPages();
 
 var app = builder.Build();
@@ -20,6 +21,7 @@
 
 app.UseAuthorization();
 
+app.MapControllers();
 app.MapRazorPages();
 
 app.Run();

appsettings.Development.json

@@ -5,5 +5,6 @@
       "Default": "Information",
       "Microsoft.AspNetCore": "Warning"
     }
-  }
+  },
+  "DataPath": "data"
 }

appsettings.json

@@ -5,5 +5,6 @@
       "Microsoft.AspNetCore": "Warning"
     }
   },
-  "AllowedHosts": "*"
+  "AllowedHosts": "*",
+  "DataPath": "/var/local/dotnet/telemetry.openrails.org"
 }