feat: add PID file and ports file support

src/NATS.Server/NatsServer.cs

@@ -42,10 +42,7 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
 
     private int _lameDuck;
 
-    // Used by future ports file implementation
-#pragma warning disable CS0169 // Field is never used
     private string? _portsFilePath;
-#pragma warning restore CS0169
 
     private static readonly TimeSpan AcceptMinSleep = TimeSpan.FromMilliseconds(10);
     private static readonly TimeSpan AcceptMaxSleep = TimeSpan.FromSeconds(1);
@@ -108,6 +105,9 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
         if (_monitorServer != null)
             await _monitorServer.DisposeAsync();
 
+        DeletePidFile();
+        DeletePortsFile();
+
         _logger.LogInformation("Server Exiting..");
         _shutdownComplete.TrySetResult();
     }
@@ -263,6 +263,9 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
             await _monitorServer.StartAsync(linked.Token);
         }
 
+        WritePidFile();
+        WritePortsFile();
+
         var tmpDelay = AcceptMinSleep;
 
         try
@@ -492,6 +495,68 @@ public sealed class NatsServer : IMessageRouter, ISubListAccess, IDisposable
         client.Account?.RemoveClient(client.Id);
     }
 
+    private void WritePidFile()
+    {
+        if (string.IsNullOrEmpty(_options.PidFile)) return;
+        try
+        {
+            File.WriteAllText(_options.PidFile, Environment.ProcessId.ToString());
+            _logger.LogDebug("Wrote PID file {PidFile}", _options.PidFile);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error writing PID file {PidFile}", _options.PidFile);
+        }
+    }
+
+    private void DeletePidFile()
+    {
+        if (string.IsNullOrEmpty(_options.PidFile)) return;
+        try
+        {
+            if (File.Exists(_options.PidFile))
+                File.Delete(_options.PidFile);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error deleting PID file {PidFile}", _options.PidFile);
+        }
+    }
+
+    private void WritePortsFile()
+    {
+        if (string.IsNullOrEmpty(_options.PortsFileDir)) return;
+        try
+        {
+            var exeName = Path.GetFileNameWithoutExtension(Environment.ProcessPath ?? "nats-server");
+            var fileName = $"{exeName}_{Environment.ProcessId}.ports";
+            _portsFilePath = Path.Combine(_options.PortsFileDir, fileName);
+
+            var ports = new { client = _options.Port, monitor = _options.MonitorPort > 0 ? _options.MonitorPort : (int?)null };
+            var json = System.Text.Json.JsonSerializer.Serialize(ports);
+            File.WriteAllText(_portsFilePath, json);
+            _logger.LogDebug("Wrote ports file {PortsFile}", _portsFilePath);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error writing ports file to {PortsFileDir}", _options.PortsFileDir);
+        }
+    }
+
+    private void DeletePortsFile()
+    {
+        if (_portsFilePath == null) return;
+        try
+        {
+            if (File.Exists(_portsFilePath))
+                File.Delete(_portsFilePath);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Error deleting ports file {PortsFile}", _portsFilePath);
+        }
+    }
+
     public void Dispose()
     {
         if (!IsShuttingDown)

tests/NATS.Server.Tests/ServerTests.cs

@@ -842,3 +842,62 @@ public class LameDuckTests
         }
     }
 }
+
+public class PidFileTests : IDisposable
+{
+    private readonly string _tempDir = Path.Combine(Path.GetTempPath(), $"nats-test-{Guid.NewGuid():N}");
+
+    public PidFileTests() => Directory.CreateDirectory(_tempDir);
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_tempDir))
+            Directory.Delete(_tempDir, recursive: true);
+    }
+
+    private static int GetFreePort()
+    {
+        using var sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+        sock.Bind(new IPEndPoint(IPAddress.Loopback, 0));
+        return ((IPEndPoint)sock.LocalEndPoint!).Port;
+    }
+
+    [Fact]
+    public async Task Server_writes_pid_file_on_startup()
+    {
+        var pidFile = Path.Combine(_tempDir, "nats.pid");
+        var port = GetFreePort();
+        var server = new NatsServer(new NatsOptions { Port = port, PidFile = pidFile }, NullLoggerFactory.Instance);
+        _ = server.StartAsync(CancellationToken.None);
+        await server.WaitForReadyAsync();
+
+        File.Exists(pidFile).ShouldBeTrue();
+        var content = await File.ReadAllTextAsync(pidFile);
+        int.Parse(content).ShouldBe(Environment.ProcessId);
+
+        await server.ShutdownAsync();
+        File.Exists(pidFile).ShouldBeFalse();
+
+        server.Dispose();
+    }
+
+    [Fact]
+    public async Task Server_writes_ports_file_on_startup()
+    {
+        var port = GetFreePort();
+        var server = new NatsServer(new NatsOptions { Port = port, PortsFileDir = _tempDir }, NullLoggerFactory.Instance);
+        _ = server.StartAsync(CancellationToken.None);
+        await server.WaitForReadyAsync();
+
+        var portsFiles = Directory.GetFiles(_tempDir, "*.ports");
+        portsFiles.Length.ShouldBe(1);
+
+        var content = await File.ReadAllTextAsync(portsFiles[0]);
+        content.ShouldContain($"\"client\":{port}");
+
+        await server.ShutdownAsync();
+        Directory.GetFiles(_tempDir, "*.ports").Length.ShouldBe(0);
+
+        server.Dispose();
+    }
+}