diff --git a/api/api.go b/api/api.go
index a9e375e82b..97275bad0b 100644
--- a/api/api.go
+++ b/api/api.go
@@ -263,13 +263,14 @@ func postImagesCreate(c *context, w http.ResponseWriter, r *http.Request) {
 		if tag := r.Form.Get("tag"); tag != "" {
 			image += ":" + tag
 		}
-		begin := func(name string) {
-			fmt.Fprintf(wf, "{%q:%q,%q:\"Pulling %s...\",%q:{}}", "id", name, "status", image, "progressDetail")
+		callback := func(what, status string) {
+			if status == "" {
+				fmt.Fprintf(wf, "{%q:%q,%q:\"Pulling %s...\",%q:{}}", "id", what, "status", image, "progressDetail")
+			} else {
+				fmt.Fprintf(wf, "{%q:%q,%q:\"Pulling %s... : %s\",%q:{}}", "id", what, "status", image, status, "progressDetail")
+			}
 		}
-		end := func(name string) {
-			fmt.Fprintf(wf, "{%q:%q,%q:\"Pulling %s... : downloaded\",%q:{}}", "id", name, "status", image, "progressDetail")
-		}
-		c.cluster.Pull(image, begin, end)
+		c.cluster.Pull(image, callback)
 	} else { //import
 		httpError(w, "Not supported in clustering mode.", http.StatusNotImplemented)
 	}
diff --git a/cluster/cluster.go b/cluster/cluster.go
index 899cec97ac..1844363b35 100644
--- a/cluster/cluster.go
+++ b/cluster/cluster.go
@@ -3,15 +3,31 @@ package cluster
 import "github.com/samalba/dockerclient"
 
 type Cluster interface {
+	// Create a container
 	CreateContainer(config *dockerclient.ContainerConfig, name string) (*Container, error)
+
+	// Remove a container
 	RemoveContainer(container *Container, force bool) error
 
+	// Return all images
 	Images() []*Image
+
+	// Return one image matching `IdOrName`
 	Image(IdOrName string) *Image
+
+	// Return all containers
 	Containers() []*Container
+
+	// Return container the matching `IdOrName`
 	Container(IdOrName string) *Container
 
-	Pull(name string, begin, end func(string))
+	// Pull images
+	// `callback` can be called multiple time
+	//  `what` is what is being pulled
+	//  `status` is the current status, like "", "in progress" or "downloaded
+	Pull(name string, callback func(what, status string))
 
+	// Return some info about the cluster, like nb or containers / images
+	// It is pretty open, so the implementation decides what to return.
 	Info() [][2]string
 }
diff --git a/cluster/swarm/cluster.go b/cluster/swarm/cluster.go
index 57623daf8c..4e712009ca 100644
--- a/cluster/swarm/cluster.go
+++ b/cluster/swarm/cluster.go
@@ -186,14 +186,18 @@ func (c *Cluster) Image(IdOrName string) *cluster.Image {
 	return nil
 }
 
-func (c *Cluster) Pull(name string, begin, end func(string)) {
+func (c *Cluster) Pull(name string, callback func(what, status string)) {
 	size := len(c.nodes)
 	done := make(chan bool, size)
 	for _, n := range c.nodes {
 		go func(nn *node) {
-			begin(nn.Name())
-			nn.Pull(name)
-			end(nn.Name())
+			if callback != nil {
+				callback(nn.Name(), "")
+			}
+			nn.pull(name)
+			if callback != nil {
+				callback(nn.Name(), "downloaded")
+			}
 			done <- true
 		}(n)
 	}