feat: watch blueprint.yaml for update and auto resend

common.go

@@ -18,6 +18,7 @@ import (
 	"github.com/fosrl/newt/logger"
 	"github.com/fosrl/newt/proxy"
 	"github.com/fosrl/newt/websocket"
+	"github.com/fsnotify/fsnotify"
 	"golang.org/x/net/icmp"
 	"golang.org/x/net/ipv4"
 	"golang.zx2c4.com/wireguard/tun/netstack"
@@ -600,3 +601,61 @@ func sendBlueprint(client *websocket.Client, file string) error {
 
 	return nil
 }
+
+func watchBlueprintFile(ctx context.Context, filePath string, send func() error) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		logger.Error("blueprint watcher: failed to create: %v", err)
+		return
+	}
+	defer watcher.Close()
+
+	if err := watcher.Add(filePath); err != nil {
+		logger.Error("blueprint watcher: failed to watch %s: %v", filePath, err)
+		return
+	}
+
+	logger.Info("Watching blueprint file for changes: %s", filePath)
+
+	var debounce *time.Timer
+	scheduleSend := func() {
+		if debounce != nil {
+			debounce.Stop()
+		}
+		debounce = time.AfterFunc(500*time.Millisecond, func() {
+			logger.Info("Blueprint file changed, resending...")
+			if err := send(); err != nil {
+				logger.Error("blueprint watcher: resend failed: %v", err)
+			}
+		})
+	}
+
+	for {
+		select {
+		case <-ctx.Done():
+			if debounce != nil {
+				debounce.Stop()
+			}
+			return
+		case event, ok := <-watcher.Events:
+			if !ok {
+				return
+			}
+			switch {
+			case event.Has(fsnotify.Write) || event.Has(fsnotify.Create):
+				if event.Has(fsnotify.Create) {
+					_ = watcher.Add(filePath)
+				}
+				scheduleSend()
+			case event.Has(fsnotify.Remove) || event.Has(fsnotify.Rename):
+				_ = watcher.Add(filePath)
+				scheduleSend()
+			}
+		case err, ok := <-watcher.Errors:
+			if !ok {
+				return
+			}
+			logger.Error("blueprint watcher: %v", err)
+		}
+	}
+}

common_test.go

@@ -1,10 +1,151 @@
 package main
 
 import (
+	"context"
 	"net"
+	"os"
+	"path/filepath"
+	"sync/atomic"
 	"testing"
+	"time"
 )
 
+func TestWatchBlueprintFile_WriteTriggersSend(t *testing.T) {
+	f, err := os.CreateTemp(t.TempDir(), "blueprint-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	var calls atomic.Int32
+	go watchBlueprintFile(ctx, f.Name(), func() error {
+		calls.Add(1)
+		return nil
+	})
+
+	time.Sleep(50 * time.Millisecond)
+
+	if err := os.WriteFile(f.Name(), []byte("content"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(700 * time.Millisecond)
+
+	if calls.Load() != 1 {
+		t.Errorf("expected 1 send call, got %d", calls.Load())
+	}
+}
+
+func TestWatchBlueprintFile_DebounceCoalescesEvents(t *testing.T) {
+	f, err := os.CreateTemp(t.TempDir(), "blueprint-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	var calls atomic.Int32
+	go watchBlueprintFile(ctx, f.Name(), func() error {
+		calls.Add(1)
+		return nil
+	})
+
+	time.Sleep(50 * time.Millisecond)
+
+	for i := 0; i < 5; i++ {
+		if err := os.WriteFile(f.Name(), []byte("change"), 0644); err != nil {
+			t.Fatal(err)
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+
+	time.Sleep(700 * time.Millisecond)
+
+	if calls.Load() != 1 {
+		t.Errorf("expected 1 send call after debounce, got %d", calls.Load())
+	}
+}
+
+func TestWatchBlueprintFile_ContextCancellationStops(t *testing.T) {
+	f, err := os.CreateTemp(t.TempDir(), "blueprint-*.yaml")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	done := make(chan struct{})
+	go func() {
+		watchBlueprintFile(ctx, f.Name(), func() error { return nil })
+		close(done)
+	}()
+
+	time.Sleep(50 * time.Millisecond)
+	cancel()
+
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Error("watchBlueprintFile did not exit after context cancellation")
+	}
+}
+
+func TestWatchBlueprintFile_AtomicWriteTriggersSend(t *testing.T) {
+	dir := t.TempDir()
+	target := filepath.Join(dir, "blueprint.yaml")
+	if err := os.WriteFile(target, []byte("initial"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	var calls atomic.Int32
+	go watchBlueprintFile(ctx, target, func() error {
+		calls.Add(1)
+		return nil
+	})
+
+	time.Sleep(50 * time.Millisecond)
+
+	tmp := filepath.Join(dir, "blueprint.yaml.tmp")
+	if err := os.WriteFile(tmp, []byte("updated"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Rename(tmp, target); err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(700 * time.Millisecond)
+
+	if calls.Load() < 1 {
+		t.Errorf("expected at least 1 send call after atomic write, got %d", calls.Load())
+	}
+}
+
+func TestWatchBlueprintFile_MissingFileReturnsGracefully(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	done := make(chan struct{})
+	go func() {
+		watchBlueprintFile(ctx, "/nonexistent/path/blueprint.yaml", func() error { return nil })
+		close(done)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(2 * time.Second):
+		t.Error("watchBlueprintFile did not return for missing file")
+	}
+}
+
 func TestParseTargetString(t *testing.T) {
 	tests := []struct {
 		name           string
@@ -13,7 +154,6 @@ func TestParseTargetString(t *testing.T) {
 		wantTargetAddr string
 		wantErr        bool
 	}{
-		// IPv4 test cases
 		{
 			name:           "valid IPv4 basic",
 			input:          "3001:192.168.1.1:80",
@@ -35,8 +175,6 @@ func TestParseTargetString(t *testing.T) {
 			wantTargetAddr: "10.0.0.1:443",
 			wantErr:        false,
 		},
-
-		// IPv6 test cases
 		{
 			name:           "valid IPv6 loopback",
 			input:          "3001:[::1]:8080",
@@ -72,8 +210,6 @@ func TestParseTargetString(t *testing.T) {
 			wantTargetAddr: "[::ffff:192.168.1.1]:6000",
 			wantErr:        false,
 		},
-
-		// Hostname test cases
 		{
 			name:           "valid hostname",
 			input:          "8080:example.com:80",
@@ -95,8 +231,6 @@ func TestParseTargetString(t *testing.T) {
 			wantTargetAddr: "localhost:3000",
 			wantErr:        false,
 		},
-
-		// Error cases
 		{
 			name:    "invalid - no colons",
 			input:   "invalid",
@@ -169,7 +303,7 @@ func TestParseTargetString(t *testing.T) {
 			}
 
 			if tt.wantErr {
-				return // Don't check other values if we expected an error
+				return
 			}
 
 			if listenPort != tt.wantListenPort {
@@ -183,7 +317,7 @@ func TestParseTargetString(t *testing.T) {
 	}
 }
 
-// TestParseTargetStringNetDialCompatibility verifies that the output is compatible with net.Dial
+// TestParseTargetStringNetDialCompatibility verifies that the output is compatible with net.Dial.
 func TestParseTargetStringNetDialCompatibility(t *testing.T) {
 	tests := []struct {
 		name  string
@@ -201,8 +335,6 @@ func TestParseTargetStringNetDialCompatibility(t *testing.T) {
 				t.Fatalf("parseTargetString(%q) unexpected error: %v", tt.input, err)
 			}
 
-			// Verify the format is valid for net.Dial by checking it can be split back
-			// This doesn't actually dial, just validates the format
 			_, _, err = net.SplitHostPort(targetAddr)
 			if err != nil {
 				t.Errorf("parseTargetString(%q) produced invalid net.Dial format %q: %v", tt.input, targetAddr, err)
@@ -248,4 +380,4 @@ func TestShouldFireRecovery(t *testing.T) {
 			}
 		})
 	}
-}
+}

go.mod

@@ -46,6 +46,7 @@ require (
 	github.com/docker/go-connections v0.7.0 // indirect
 	github.com/docker/go-units v0.5.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/google/btree v1.1.3 // indirect

go.sum

@@ -24,6 +24,8 @@ github.com/docker/go-units v0.5.0 h1:69rxXcBk27SvSaaxTtLh/8llcHD8vYHT7WSdRZ/jvr4
 github.com/docker/go-units v0.5.0/go.mod h1:fgPhTUdO+D/Jk86RDLlptpiXQzgHJF7gydDDbaIK4Dk=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
+github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
+github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
 github.com/gaissmai/bart v0.26.1 h1:+w4rnLGNlA2GDVn382Tfe3jOsK5vOr5n4KmigJ9lbTo=
 github.com/gaissmai/bart v0.26.1/go.mod h1:GREWQfTLRWz/c5FTOsIw+KkscuFkIV5t8Rp7Nd1Td5c=
 github.com/go-crypt/crypt v0.14.15 h1:q1i5OMpL05r935IxWmXgpDAVF0nvi4SMoHhGXLBQUEQ=

main.go

@@ -2245,6 +2245,12 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 		}
 	}
 
+	if blueprintFile != "" {
+		go watchBlueprintFile(ctx, blueprintFile, func() error {
+			return sendBlueprint(client, blueprintFile)
+		})
+	}
+
 	// Wait for context cancellation (from signal or service stop)
 	<-ctx.Done()