Add /system/df API endpoint

This endpoint return data regarding the space used by docker on disk

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>
Upstream-commit: f2e11fb8d1284626d40bb916ad6a21a316e5ab9c
Component: engine

components/engine/api/server/router/system/backend.go

@@ -14,6 +14,7 @@ import (
 type Backend interface {
 	SystemInfo() (*types.Info, error)
 	SystemVersion() types.Version
+	SystemDiskUsage() (*types.DiskUsage, error)
 	SubscribeToEvents(since, until time.Time, ef filters.Args) ([]events.Message, chan interface{})
 	UnsubscribeFromEvents(chan interface{})
 	AuthenticateToRegistry(ctx context.Context, authConfig *types.AuthConfig) (string, string, error)

components/engine/api/server/router/system/system.go

@@ -26,6 +26,7 @@ func NewRouter(b Backend, c *cluster.Cluster) router.Router {
 		router.Cancellable(router.NewGetRoute("/events", r.getEvents)),
 		router.NewGetRoute("/info", r.getInfo),
 		router.NewGetRoute("/version", r.getVersion),
+		router.NewGetRoute("/system/df", r.getDiskUsage),
 		router.NewPostRoute("/auth", r.postAuth),
 	}
 

components/engine/api/server/router/system/system_routes.go

@@ -56,6 +56,15 @@ func (s *systemRouter) getVersion(ctx context.Context, w http.ResponseWriter, r
 	return httputils.WriteJSON(w, http.StatusOK, info)
 }
 
+func (s *systemRouter) getDiskUsage(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
+	du, err := s.backend.SystemDiskUsage()
+	if err != nil {
+		return err
+	}
+
+	return httputils.WriteJSON(w, http.StatusOK, du)
+}
+
 func (s *systemRouter) getEvents(ctx context.Context, w http.ResponseWriter, r *http.Request, vars map[string]string) error {
 	if err := httputils.ParseForm(r); err != nil {
 		return err

components/engine/api/types/types.go

@@ -530,3 +530,12 @@ type Runtime struct {
 	Path string   `json:"path"`
 	Args []string `json:"runtimeArgs,omitempty"`
 }
+
+// DiskUsage contains response of Remote API:
+// GET "/system/df"
+type DiskUsage struct {
+	LayersSize int64
+	Images     []*Image
+	Containers []*Container
+	Volumes    []*Volume
+}