AUTH-2587 add config watcher and reload logic for access client forwarder

watcher/file.go

@@ -0,0 +1,58 @@
+package watcher
+
+import (
+	"github.com/fsnotify/fsnotify"
+)
+
+// File is a file watcher that notifies when a file has been changed
+type File struct {
+	watcher  *fsnotify.Watcher
+	shutdown chan struct{}
+}
+
+// NewFile is a standard constructor
+func NewFile() (*File, error) {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		return nil, err
+	}
+	f := &File{
+		watcher:  watcher,
+		shutdown: make(chan struct{}),
+	}
+	return f, nil
+}
+
+// Add adds a file to start watching
+func (f *File) Add(filepath string) error {
+	return f.watcher.Add(filepath)
+}
+
+// Shutdown stop the file watching run loop
+func (f *File) Shutdown() {
+	f.shutdown <- struct{}{}
+}
+
+// Start is a runloop to watch for files changes from the file paths added from Add()
+func (f *File) Start(notifier Notification) {
+	for {
+		select {
+		case event, ok := <-f.watcher.Events:
+			if !ok {
+				return
+			}
+			if event.Op&fsnotify.Write == fsnotify.Write {
+				notifier.WatcherItemDidChange(event.Name)
+			}
+		case err, ok := <-f.watcher.Errors:
+			if !ok {
+				return
+			}
+			notifier.WatcherDidError(err)
+
+		case <-f.shutdown:
+			f.watcher.Close()
+			return
+		}
+	}
+}

watcher/file_test.go

@@ -0,0 +1,54 @@
+package watcher
+
+import (
+	"bufio"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type mockNotifier struct {
+	eventPath string
+}
+
+func (n *mockNotifier) WatcherItemDidChange(path string) {
+	n.eventPath = path
+}
+
+func (n *mockNotifier) WatcherDidError(err error) {
+}
+
+func TestFileChanged(t *testing.T) {
+	filePath := "test_file"
+	f, err := os.Create(filePath)
+	assert.NoError(t, err)
+	defer func() {
+		f.Close()
+		os.Remove(filePath)
+	}()
+
+	service, err := NewFile()
+	assert.NoError(t, err)
+
+	err = service.Add(filePath)
+	assert.NoError(t, err)
+
+	n := &mockNotifier{}
+	go service.Start(n)
+
+	f.Sync()
+
+	w := bufio.NewWriter(f)
+	_, err = w.WriteString("hello Austin, do you like my file watcher?\n")
+	assert.NoError(t, err)
+	err = w.Flush()
+	assert.NoError(t, err)
+
+	// give it time to trigger
+	time.Sleep(10 * time.Millisecond)
+	service.Shutdown()
+
+	assert.Equal(t, filePath, n.eventPath, "notifier didn't get an new file write event")
+}

watcher/notify.go

@@ -0,0 +1,14 @@
+package watcher
+
+// Notification is the delegate methods from the Notifier
+type Notification interface {
+	WatcherItemDidChange(string)
+	WatcherDidError(error)
+}
+
+// Notifier is the base interface for file watching
+type Notifier interface {
+	Start(Notification)
+	Add(string) error
+	Shutdown()
+}