Skip updating containers where no local image info can be retrieved (#612)

* Revert "Image of running container no longer needed locally (#571)"

This reverts commit 6da66fb312.

* Update client.go

* fix: skip updating when no image info can be retrieved

This will allow watchtower to continue even though the image info for a
container cannot be retrieved. If this happens one warning will be emitted
and the container will be skipped, unless NoRestart or OnlyMonitor is supplied

internal/actions/update.go

@@ -1,6 +1,7 @@
 package actions
 
 import (
+	"errors"
 	"github.com/containrrr/watchtower/internal/util"
 	"github.com/containrrr/watchtower/pkg/container"
 	"github.com/containrrr/watchtower/pkg/lifecycle"
@@ -25,11 +26,13 @@ func Update(client container.Client, params types.UpdateParams) error {
 		return err
 	}
 
-	for i, container := range containers {
-		stale, err := client.IsContainerStale(container)
+	for i, targetContainer := range containers {
+		stale, err := client.IsContainerStale(targetContainer)
+		if stale && !params.NoRestart && !params.MonitorOnly && !targetContainer.HasImageInfo() {
+			err = errors.New("no available image info")
+		}
 		if err != nil {
-			log.Infof("Unable to update container %s. Proceeding to next.", containers[i].Name())
-			log.Debug(err)
+			log.Infof("Unable to update container %q: %v. Proceeding to next.", containers[i].Name(), err)
 			stale = false
 		}
 		containers[i].Stale = stale
@@ -89,12 +92,12 @@ func stopStaleContainer(container container.Container, client container.Client,
 func restartContainersInSortedOrder(containers []container.Container, client container.Client, params types.UpdateParams) {
 	imageIDs := make(map[string]bool)
 
-	for _, container := range containers {
-		if !container.Stale {
+	for _, staleContainer := range containers {
+		if !staleContainer.Stale {
 			continue
 		}
-		restartStaleContainer(container, client, params)
-		imageIDs[container.ImageID()] = true
+		restartStaleContainer(staleContainer, client, params)
+		imageIDs[staleContainer.ImageID()] = true
 	}
 	if params.Cleanup {
 		for imageID := range imageIDs {

pkg/container/client.go

@@ -119,8 +119,12 @@ func (client dockerClient) GetContainer(containerID string) (Container, error) {
 		return Container{}, err
 	}
 
-	container := Container{containerInfo: &containerInfo}
-	return container, nil
+	imageInfo, _, err := client.api.ImageInspectWithRaw(bg, containerInfo.Image)
+	if err != nil {
+		log.Warnf("Failed to retrieve container image info: %v", err)
+	}
+
+	return Container{containerInfo: &containerInfo, imageInfo: &imageInfo}, nil
 }
 
 func (client dockerClient) StopContainer(c Container, timeout time.Duration) error {

pkg/container/container.go

@@ -221,3 +221,8 @@ func (c Container) hostConfig() *dockercontainer.HostConfig {
 
 	return hostConfig
 }
+
+// HasImageInfo returns whether image information could be retrieved for the container
+func (c Container) HasImageInfo() bool {
+	return c.imageInfo != nil
+}