feat: add CLI flags for debug/trace modes, file logging, syslog, color, timestamps

src/NATS.Server.Host/Program.cs

@@ -1,15 +1,10 @@
 using NATS.Server;
 using Serilog;
-
+using Serilog.Sinks.SystemConsole.Themes;
-Log.Logger = new LoggerConfiguration()
-    .MinimumLevel.Debug()
-    .Enrich.FromLogContext()
-    .WriteTo.Console(outputTemplate: "[{Timestamp:HH:mm:ss} {Level:u3}] {Message:lj}{NewLine}{Exception}")
-    .CreateLogger();
 
 var options = new NatsOptions();
 
-// Simple CLI argument parsing
+// Parse ALL CLI flags into NatsOptions first
 for (int i = 0; i < args.Length; i++)
 {
     switch (args[i])
@@ -55,9 +50,89 @@ for (int i = 0; i < args.Length; i++)
         case "--tlsverify":
             options.TlsVerify = true;
             break;
+        case "-D":
+            options.Debug = true;
+            break;
+        case "-V" or "-T":
+            options.Trace = true;
+            break;
+        case "-DV":
+            options.Debug = true;
+            options.Trace = true;
+            break;
+        case "--log_file" when i + 1 < args.Length:
+            options.LogFile = args[++i];
+            break;
+        case "--log_size_limit" when i + 1 < args.Length:
+            options.LogSizeLimit = long.Parse(args[++i]);
+            break;
+        case "--log_max_files" when i + 1 < args.Length:
+            options.LogMaxFiles = int.Parse(args[++i]);
+            break;
+        case "--logtime" when i + 1 < args.Length:
+            options.Logtime = bool.Parse(args[++i]);
+            break;
+        case "--logtime_utc":
+            options.LogtimeUTC = true;
+            break;
+        case "--syslog":
+            options.Syslog = true;
+            break;
+        case "--remote_syslog" when i + 1 < args.Length:
+            options.RemoteSyslog = args[++i];
+            break;
     }
 }
 
+// Build Serilog configuration from options
+var logConfig = new LoggerConfiguration()
+    .Enrich.FromLogContext();
+
+// Set minimum level based on flags
+if (options.Trace)
+    logConfig.MinimumLevel.Verbose();
+else if (options.Debug)
+    logConfig.MinimumLevel.Debug();
+else
+    logConfig.MinimumLevel.Information();
+
+// Build output template
+var timestampFormat = options.LogtimeUTC
+    ? "{Timestamp:yyyy/MM/dd HH:mm:ss.ffffff} "
+    : "{Timestamp:HH:mm:ss} ";
+var template = options.Logtime
+    ? $"[{timestampFormat}{{Level:u3}}] {{Message:lj}}{{NewLine}}{{Exception}}"
+    : "[{Level:u3}] {Message:lj}{NewLine}{Exception}";
+
+// Console sink with color auto-detection
+if (!Console.IsOutputRedirected)
+    logConfig.WriteTo.Console(outputTemplate: template, theme: AnsiConsoleTheme.Code);
+else
+    logConfig.WriteTo.Console(outputTemplate: template);
+
+// File sink with rotation
+if (!string.IsNullOrEmpty(options.LogFile))
+{
+    logConfig.WriteTo.File(
+        options.LogFile,
+        fileSizeLimitBytes: options.LogSizeLimit > 0 ? options.LogSizeLimit : null,
+        retainedFileCountLimit: options.LogMaxFiles > 0 ? options.LogMaxFiles : null,
+        rollOnFileSizeLimit: options.LogSizeLimit > 0,
+        outputTemplate: template);
+}
+
+// Syslog sink
+if (!string.IsNullOrEmpty(options.RemoteSyslog))
+{
+    logConfig.WriteTo.UdpSyslog(options.RemoteSyslog);
+}
+else if (options.Syslog)
+{
+    logConfig.WriteTo.LocalSyslog("nats-server");
+}
+
+Log.Logger = logConfig.CreateLogger();
+
 using var loggerFactory = new Serilog.Extensions.Logging.SerilogLoggerFactory(Log.Logger);
 using var server = new NatsServer(options, loggerFactory);