Merge pull request #8213 from brahmaroutu/pull_status_2404

Print a status message when pull command is executed

docs/man/docker-pull.1.md

@@ -23,6 +23,8 @@ It is also possible to specify a non-default registry to pull from.
 # EXAMPLES
 
 # Pull a repository with multiple images
+# Note that if the  image is previously downloaded then the status would be
+# 'Status: Image is up to date for fedora'
 
     $ sudo docker pull fedora
     Pulling repository fedora
@@ -31,6 +33,8 @@ It is also possible to specify a non-default registry to pull from.
     511136ea3c5a: Download complete
     73bd853d2ea5: Download complete
 
+    Status: Downloaded newer image for fedora
+
     $ sudo docker images
     REPOSITORY   TAG         IMAGE ID        CREATED      VIRTUAL SIZE
     fedora       rawhide     ad57ef8d78d7    5 days ago   359.3 MB
@@ -39,6 +43,8 @@ It is also possible to specify a non-default registry to pull from.
     fedora       latest      105182bb5e8b    5 days ago   372.7 MB
 
 # Pull an image, manually specifying path to the registry and tag
+# Note that if the  image is previously downloaded then the status would be
+# 'Status: Image is up to date for registry.hub.docker.com/fedora:20'
 
     $ sudo docker pull registry.hub.docker.com/fedora:20
     Pulling repository fedora
@@ -46,6 +52,8 @@ It is also possible to specify a non-default registry to pull from.
     511136ea3c5a: Download complete 
     fd241224e9cf: Download complete 
 
+    Status: Downloaded newer image for registry.hub.docker.com/fedora:20
+
     $ sudo docker images
     REPOSITORY   TAG         IMAGE ID        CREATED      VIRTUAL SIZE
     fedora       20          3f2fed40e4b0    4 days ago   372.7 MB

docs/sources/userguide/dockerimages.md

@@ -93,6 +93,8 @@ download the `centos` image.
     ef52fb1fe610: Download complete
     . . .
 
+    Status: Downloaded newer image for centos
+
 We can see that each layer of the image has been pulled down and now we
 can run a container from this image and we won't have to wait to
 download the image.

docs/sources/userguide/dockerrepos.md

@@ -67,6 +67,8 @@ Once you've found the image you want, you can download it with `docker pull <ima
     511136ea3c5a: Download complete
     7064731afe90: Download complete
 
+    Status: Downloaded newer image for centos
+
 You now have an image from which you can run containers.
 
 ## Contributing to Docker Hub

graph/pull.go

@@ -122,6 +122,8 @@ func (s *TagStore) pullRepository(r *registry.Session, out io.Writer, localName,
 	}
 
 	errors := make(chan error)
+
+	layers_downloaded := false
 	for _, image := range repoData.ImgList {
 		downloadImage := func(img *registry.ImgData) {
 			if askedTag != "" && img.Tag != askedTag {
@@ -158,15 +160,17 @@ func (s *TagStore) pullRepository(r *registry.Session, out io.Writer, localName,
 
 			out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s", img.Tag, localName), nil))
 			success := false
-			var lastErr error
+			var lastErr, err error
+			var is_downloaded bool
 			if mirrors != nil {
 				for _, ep := range mirrors {
 					out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, mirror: %s", img.Tag, localName, ep), nil))
-					if err := s.pullImage(r, out, img.ID, ep, repoData.Tokens, sf); err != nil {
+					if is_downloaded, err = s.pullImage(r, out, img.ID, ep, repoData.Tokens, sf); err != nil {
 						// Don't report errors when pulling from mirrors.
 						log.Debugf("Error pulling image (%s) from %s, mirror: %s, %s", img.Tag, localName, ep, err)
 						continue
 					}
+					layers_downloaded = layers_downloaded || is_downloaded
 					success = true
 					break
 				}
@@ -174,13 +178,14 @@ func (s *TagStore) pullRepository(r *registry.Session, out io.Writer, localName,
 			if !success {
 				for _, ep := range repoData.Endpoints {
 					out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Pulling image (%s) from %s, endpoint: %s", img.Tag, localName, ep), nil))
-					if err := s.pullImage(r, out, img.ID, ep, repoData.Tokens, sf); err != nil {
+					if is_downloaded, err = s.pullImage(r, out, img.ID, ep, repoData.Tokens, sf); err != nil {
 						// It's not ideal that only the last error is returned, it would be better to concatenate the errors.
 						// As the error is also given to the output stream the user will see the error.
 						lastErr = err
 						out.Write(sf.FormatProgress(utils.TruncateID(img.ID), fmt.Sprintf("Error pulling image (%s) from %s, endpoint: %s, %s", img.Tag, localName, ep, err), nil))
 						continue
 					}
+					layers_downloaded = layers_downloaded || is_downloaded
 					success = true
 					break
 				}
@@ -227,18 +232,24 @@ func (s *TagStore) pullRepository(r *registry.Session, out io.Writer, localName,
 		}
 	}
 
+	requestedTag := localName
+	if len(askedTag) > 0 {
+		requestedTag = localName + ":" + askedTag
+	}
+	WriteStatus(requestedTag, out, sf, layers_downloaded)
 	return nil
 }
 
-func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint string, token []string, sf *utils.StreamFormatter) error {
+func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint string, token []string, sf *utils.StreamFormatter) (bool, error) {
 	history, err := r.GetRemoteHistory(imgID, endpoint, token)
 	if err != nil {
-		return err
+		return false, err
 	}
 	out.Write(sf.FormatProgress(utils.TruncateID(imgID), "Pulling dependent layers", nil))
 	// FIXME: Try to stream the images?
 	// FIXME: Launch the getRemoteImage() in goroutines
 
+	layers_downloaded := false
 	for i := len(history) - 1; i >= 0; i-- {
 		id := history[i]
 
@@ -262,15 +273,16 @@ func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint
 				imgJSON, imgSize, err = r.GetRemoteImageJSON(id, endpoint, token)
 				if err != nil && j == retries {
 					out.Write(sf.FormatProgress(utils.TruncateID(id), "Error pulling dependent layers", nil))
-					return err
+					return layers_downloaded, err
 				} else if err != nil {
 					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
 					continue
 				}
 				img, err = image.NewImgJSON(imgJSON)
+				layers_downloaded = true
 				if err != nil && j == retries {
 					out.Write(sf.FormatProgress(utils.TruncateID(id), "Error pulling dependent layers", nil))
-					return fmt.Errorf("Failed to parse json: %s", err)
+					return layers_downloaded, fmt.Errorf("Failed to parse json: %s", err)
 				} else if err != nil {
 					time.Sleep(time.Duration(j) * 500 * time.Millisecond)
 					continue
@@ -295,8 +307,9 @@ func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint
 					continue
 				} else if err != nil {
 					out.Write(sf.FormatProgress(utils.TruncateID(id), "Error pulling dependent layers", nil))
-					return err
+					return layers_downloaded, err
 				}
+				layers_downloaded = true
 				defer layer.Close()
 
 				err = s.graph.Register(img, imgJSON,
@@ -306,14 +319,21 @@ func (s *TagStore) pullImage(r *registry.Session, out io.Writer, imgID, endpoint
 					continue
 				} else if err != nil {
 					out.Write(sf.FormatProgress(utils.TruncateID(id), "Error downloading dependent layers", nil))
-					return err
+					return layers_downloaded, err
 				} else {
 					break
 				}
 			}
 		}
 		out.Write(sf.FormatProgress(utils.TruncateID(id), "Download complete", nil))
-
 	}
-	return nil
+	return layers_downloaded, nil
+}
+
+func WriteStatus(requestedTag string, out io.Writer, sf *utils.StreamFormatter, layers_downloaded bool) {
+	if layers_downloaded {
+		out.Write(sf.FormatStatus("", "Status: Downloaded newer image for %s", requestedTag))
+	} else {
+		out.Write(sf.FormatStatus("", "Status: Image is up to date for %s", requestedTag))
+	}
 }