Add NLog file logging configuration and error handling

Integrate NLog for structured file-based logging by adding configuration to appsettings.json and initializing NLog in Program.cs. Wrap application startup in a try-catch block to log unhandled exceptions. No changes to core application logic.

Program.cs

@@ -1,19 +1,26 @@
 using Microsoft.AspNetCore.Authentication.Negotiate;
 using Microsoft.OpenApi.Models;
+using NLog;
+using NLog.Web;
 
-var builder = WebApplication.CreateBuilder(args);
+var logger = LogManager.Setup().LoadConfigurationFromAppSettings().GetCurrentClassLogger();
+logger.Info("Logging initialized!");
+
+try
+{
+    var builder = WebApplication.CreateBuilder(args);
 
 
-// Add services to the container.
+    // Add services to the container.
 
-builder.Services.AddControllers();
+    builder.Services.AddControllers();
     builder.Services.AddAuthentication(NegotiateDefaults.AuthenticationScheme)
         .AddNegotiate();
-builder.Services.AddAuthorization();
-// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
-builder.Services.AddEndpointsApiExplorer();
-builder.Services.AddSwaggerGen(options =>
-{
+    builder.Services.AddAuthorization();
+    // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
+    builder.Services.AddEndpointsApiExplorer();
+    builder.Services.AddSwaggerGen(options =>
+    {
         options.SwaggerDoc("v1", new OpenApiInfo
         {
             Title = "FakeNTLMServer",
@@ -47,26 +54,32 @@ builder.Services.AddSwaggerGen(options =>
         var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
         if (File.Exists(xmlPath))
             options.IncludeXmlComments(xmlPath);
-});
+    });
 
-var app = builder.Build();
+    var app = builder.Build();
 
-// Configure the HTTP request pipeline.
-if (app.Environment.IsDevelopment() || app.Configuration.GetValue<bool>("EnableSwagger"))
-{
+    // Configure the HTTP request pipeline.
+    if (app.Environment.IsDevelopment() || app.Configuration.GetValue<bool>("EnableSwagger"))
+    {
         app.UseSwagger();
         app.UseSwaggerUI(options =>
         {
             // Enable sending credentials (NTLM tokens) with Swagger UI requests
             options.ConfigObject.AdditionalItems["withCredentials"] = true;
         });
+    }
+
+    app.UseHttpsRedirection();
+
+    app.UseAuthentication();
+    app.UseAuthorization();
+
+    app.MapControllers();
+
+    app.Run();
+}
+catch (Exception ex)
+{
+    logger.Error(ex, "Stopped program because of exception");
+    throw;
 }
-
-app.UseHttpsRedirection();
-
-app.UseAuthentication();
-app.UseAuthorization();
-
-app.MapControllers();
-
-app.Run();

appsettings.json

@@ -11,5 +11,48 @@
       "Protocols": "Http1"
     }
   },
-  "EnableSwagger": true
+  "EnableSwagger": true,
+  "NLog": {
+    "throwConfigExceptions": true,
+    "variables": {
+      "logDirectory": "E:\\LogFiles\\Digital Data\\FakeNTLMServer",
+      "logFileNamePrefix": "${shortdate}-FakeNTLMServer"
+    },
+    "targets": {
+      "infoLogs": {
+        "type": "File",
+        "fileName": "${logDirectory}\\${logFileNamePrefix}-Info.log",
+        "maxArchiveDays": 30
+      },
+      "errorLogs": {
+        "type": "File",
+        "fileName": "${logDirectory}\\${logFileNamePrefix}-Error.log",
+        "maxArchiveDays": 30
+      },
+      "criticalLogs": {
+        "type": "File",
+        "fileName": "${logDirectory}\\${logFileNamePrefix}-Critical.log",
+        "maxArchiveDays": 30
+      }
+    },
+    // Trace, Debug, Info, Warn, Error and *Fatal*
+    "rules": [
+      {
+        "logger": "*",
+        "minLevel": "Info",
+        "maxLevel": "Warn",
+        "writeTo": "infoLogs"
+      },
+      {
+        "logger": "*",
+        "level": "Error",
+        "writeTo": "errorLogs"
+      },
+      {
+        "logger": "*",
+        "level": "Fatal",
+        "writeTo": "criticalLogs"
+      }
+    ]
+  }
 }