Migrate the use of fsnotify to fswatcher in cert_watcher.go (jaegertr…

…acing#4232)

Signed-off-by: haanhvu <haanh6594@gmail.com>

## Which problem is this PR solving?
First step for jaegertracing#3924 as discussed
[here](jaegertracing#3924 (comment))

---------

Signed-off-by: haanhvu <haanh6594@gmail.com>

pkg/config/tlscfg/cert_watcher.go

@@ -27,6 +27,8 @@ import (
 
 	"github.com/fsnotify/fsnotify"
 	"go.uber.org/zap"
+
+	"github.com/jaegertracing/jaeger/pkg/fswatcher"
 )
 
 // certWatcher watches filesystem changes on certificates supplied via Options
@@ -37,7 +39,7 @@ type certWatcher struct {
 	mu           sync.RWMutex
 	opts         Options
 	logger       *zap.Logger
-	watcher      *fsnotify.Watcher
+	watcher      fswatcher.Watcher
 	cert         *tls.Certificate
 	caHash       string
 	clientCAHash string
@@ -58,7 +60,7 @@ func newCertWatcher(opts Options, logger *zap.Logger) (*certWatcher, error) {
 		cert = &c
 	}
 
-	watcher, err := fsnotify.NewWatcher()
+	watcher, err := fswatcher.NewWatcher()
 	if err != nil {
 		return nil, err
 	}
@@ -148,7 +150,7 @@ func (w *certWatcher) setupWatchedPaths() error {
 func (w *certWatcher) watchChangesLoop(rootCAs, clientCAs *x509.CertPool) {
 	for {
 		select {
-		case event, ok := <-w.watcher.Events:
+		case event, ok := <-w.watcher.Events():
 			if !ok {
 				return // channel closed means the watcher is closed
 			}
@@ -158,7 +160,7 @@ func (w *certWatcher) watchChangesLoop(rootCAs, clientCAs *x509.CertPool) {
 				event.Op&fsnotify.Remove == fsnotify.Remove {
 				w.attemptReload(rootCAs, clientCAs)
 			}
-		case err, ok := <-w.watcher.Errors:
+		case err, ok := <-w.watcher.Errors():
 			if !ok {
 				return // channel closed means the watcher is closed
 			}

pkg/config/tlscfg/cert_watcher_test.go

@@ -23,12 +23,13 @@ import (
 	"testing"
 	"time"
 
-	"github.com/fsnotify/fsnotify"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/zap"
 	"go.uber.org/zap/zapcore"
 	"go.uber.org/zap/zaptest/observer"
+
+	"github.com/jaegertracing/jaeger/pkg/fswatcher"
 )
 
 const (
@@ -340,7 +341,7 @@ func createTimestampDir(t *testing.T, dir string, ca, cert, key string) {
 }
 
 func TestAddCertsToWatch_err(t *testing.T) {
-	watcher, err := fsnotify.NewWatcher()
+	watcher, err := fswatcher.NewWatcher()
 	require.NoError(t, err)
 	defer watcher.Close()
 	w := &certWatcher{

pkg/fswatcher/fs_watcher.go

@@ -20,6 +20,7 @@ import "github.com/fsnotify/fsnotify"
 // Primarily used for mocking the fsnotify lib.
 type Watcher interface {
 	Add(name string) error
+	Close() error
 	Events() chan fsnotify.Event
 	Errors() chan error
 }
@@ -34,6 +35,11 @@ func (f *fsnotifyWatcherWrapper) Add(name string) error {
 	return f.fsnotifyWatcher.Add(name)
 }
 
+// Close closes the watcher.
+func (f *fsnotifyWatcherWrapper) Close() error {
+	return f.fsnotifyWatcher.Close()
+}
+
 // Events returns the fsnotify.Watcher's Events chan.
 func (f *fsnotifyWatcherWrapper) Events() chan fsnotify.Event {
 	return f.fsnotifyWatcher.Events

pkg/fswatcher/fs_watcher_test.go

@@ -32,6 +32,9 @@ func TestFsWatcher(t *testing.T) {
 	err = w.Add("../../cmd/query/app/fixture/ui-config.json")
 	assert.NoError(t, err)
 
+	err = w.Close()
+	assert.NoError(t, err)
+
 	events := w.Events()
 	assert.NotZero(t, events)