refactor: docker event watcher

internal/idlewatcher/provider/docker.go

@@ -12,7 +12,7 @@ import (
 
 type DockerProvider struct {
 	client      *docker.SharedClient
-	watcher     *watcher.DockerWatcher
+	watcher     watcher.DockerWatcher
 	containerID string
 }
 

internal/watcher/docker_watcher.go

@@ -15,10 +15,7 @@ import (
 )
 
 type (
-	DockerWatcher struct {
+	DockerWatcher     string
-		host   string
-		client *docker.SharedClient
-	}
 	DockerListOptions = docker_events.ListOptions
 )
 
@@ -58,14 +55,75 @@ func DockerFilterContainerNameID(nameOrID string) filters.KeyValuePair {
 	return filters.Arg("container", nameOrID)
 }
 
-func NewDockerWatcher(host string) *DockerWatcher {
+func NewDockerWatcher(host string) DockerWatcher {
-	return &DockerWatcher{host: host}
+	return DockerWatcher(host)
 }
 
-func (w *DockerWatcher) Events(ctx context.Context) (<-chan Event, <-chan gperr.Error) {
+func (w DockerWatcher) Events(ctx context.Context) (<-chan Event, <-chan gperr.Error) {
 	return w.EventsWithOptions(ctx, optionsDefault)
 }
 
+func (w DockerWatcher) EventsWithOptions(ctx context.Context, options DockerListOptions) (<-chan Event, <-chan gperr.Error) {
+	eventCh := make(chan Event)
+	errCh := make(chan gperr.Error)
+
+	go func() {
+		client, err := docker.NewClient(string(w))
+		if err != nil {
+			errCh <- gperr.Wrap(err, "docker watcher: failed to initialize client")
+			return
+		}
+
+		defer func() {
+			close(eventCh)
+			close(errCh)
+			client.Close()
+		}()
+
+		cEventCh, cErrCh := client.Events(ctx, options)
+		defer logging.Debug().Str("host", client.Address()).Msg("docker watcher closed")
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case msg := <-cEventCh:
+				w.handleEvent(msg, eventCh)
+			case err := <-cErrCh:
+				if err == nil {
+					continue
+				}
+				errCh <- w.parseError(err)
+				// release the error because reopening event channel may block
+				//nolint:ineffassign,wastedassign
+				err = nil
+				// trigger reload (clear routes)
+				eventCh <- reloadTrigger
+
+				retry := time.NewTicker(dockerWatcherRetryInterval)
+				defer retry.Stop()
+				ok := false
+				for !ok {
+					select {
+					case <-ctx.Done():
+						return
+					case <-retry.C:
+						if checkConnection(ctx, client) {
+							ok = true
+							break
+						}
+					}
+				}
+				// connection successful, trigger reload (reload routes)
+				eventCh <- reloadTrigger
+				// reopen event channel
+				cEventCh, cErrCh = client.Events(ctx, options)
+			}
+		}
+	}()
+
+	return eventCh, errCh
+}
+
 func (w DockerWatcher) parseError(err error) gperr.Error {
 	if errors.Is(err, context.DeadlineExceeded) {
 		return gperr.New("docker client connection timeout")
@@ -76,18 +134,7 @@ func (w DockerWatcher) parseError(err error) gperr.Error {
 	return gperr.Wrap(err)
 }
 
-func (w *DockerWatcher) checkConnection(ctx context.Context) bool {
+func (w DockerWatcher) handleEvent(event docker_events.Message, ch chan<- Event) {
-	ctx, cancel := context.WithTimeout(ctx, dockerWatcherRetryInterval)
-	defer cancel()
-	err := w.client.CheckConnection(ctx)
-	if err != nil {
-		logging.Debug().Err(err).Msg("docker watcher: connection failed")
-		return false
-	}
-	return true
-}
-
-func (w *DockerWatcher) handleEvent(event docker_events.Message, ch chan<- Event) {
 	action, ok := events.DockerEventMap[event.Action]
 	if !ok {
 		return
@@ -101,63 +148,13 @@ func (w *DockerWatcher) handleEvent(event docker_events.Message, ch chan<- Event
 	}
 }
 
-func (w *DockerWatcher) EventsWithOptions(ctx context.Context, options DockerListOptions) (<-chan Event, <-chan gperr.Error) {
+func checkConnection(ctx context.Context, client *docker.SharedClient) bool {
-	eventCh := make(chan Event)
+	ctx, cancel := context.WithTimeout(ctx, dockerWatcherRetryInterval)
-	errCh := make(chan gperr.Error)
+	defer cancel()
-
+	err := client.CheckConnection(ctx)
-	go func() {
-		var err error
-		w.client, err = docker.NewClient(w.host)
 	if err != nil {
-			errCh <- gperr.Wrap(err, "docker watcher: failed to initialize client")
+		logging.Debug().Err(err).Msg("docker watcher: connection failed")
-			return
+		return false
 	}
-
+	return true
-		defer func() {
-			close(eventCh)
-			close(errCh)
-			w.client.Close()
-		}()
-
-		cEventCh, cErrCh := w.client.Events(ctx, options)
-		defer logging.Debug().Str("host", w.client.Address()).Msg("docker watcher closed")
-		for {
-			select {
-			case <-ctx.Done():
-				return
-			case msg := <-cEventCh:
-				w.handleEvent(msg, eventCh)
-			case err := <-cErrCh:
-				if err == nil {
-					continue
-				}
-				errCh <- w.parseError(err)
-				// release the error because reopening event channel may block
-				err = nil
-				// trigger reload (clear routes)
-				eventCh <- reloadTrigger
-
-				retry := time.NewTicker(dockerWatcherRetryInterval)
-				defer retry.Stop()
-				ok := false
-				for !ok {
-					select {
-					case <-ctx.Done():
-						return
-					case <-retry.C:
-						if w.checkConnection(ctx) {
-							ok = true
-							break
-						}
-					}
-				}
-				// connection successful, trigger reload (reload routes)
-				eventCh <- reloadTrigger
-				// reopen event channel
-				cEventCh, cErrCh = w.client.Events(ctx, options)
-			}
-		}
-	}()
-
-	return eventCh, errCh
 }