Print devicemapper status details in docker info

This adds a generic Status call in the Driver api and
implements if for the devicemapper backend.

The status is an array of key/value strings rather than a map so that
we can guarantee some static order of the docker info output.

api_params.go

@@ -52,16 +52,17 @@ type APIInfo struct {
 	Debug              bool
 	Containers         int
 	Images             int
-	Driver             string `json:",omitempty"`
-	NFd                int    `json:",omitempty"`
-	NGoroutines        int    `json:",omitempty"`
-	MemoryLimit        bool   `json:",omitempty"`
-	SwapLimit          bool   `json:",omitempty"`
-	IPv4Forwarding     bool   `json:",omitempty"`
-	LXCVersion         string `json:",omitempty"`
-	NEventsListener    int    `json:",omitempty"`
-	KernelVersion      string `json:",omitempty"`
-	IndexServerAddress string `json:",omitempty"`
+	Driver             string      `json:",omitempty"`
+	DriverStatus       [][2]string `json:",omitempty"`
+	NFd                int         `json:",omitempty"`
+	NGoroutines        int         `json:",omitempty"`
+	MemoryLimit        bool        `json:",omitempty"`
+	SwapLimit          bool        `json:",omitempty"`
+	IPv4Forwarding     bool        `json:",omitempty"`
+	LXCVersion         string      `json:",omitempty"`
+	NEventsListener    int         `json:",omitempty"`
+	KernelVersion      string      `json:",omitempty"`
+	IndexServerAddress string      `json:",omitempty"`
 }
 
 type APITop struct {

aufs/aufs.go

@@ -103,6 +103,10 @@ func (a *AufsDriver) String() string {
 	return "aufs"
 }
 
+func (d *AufsDriver) Status() [][2]string {
+	return nil
+}
+
 // Three folders are created for each id
 // mnt, layers, and diff
 func (a *AufsDriver) Create(id, parent string) error {

commands.go

@@ -461,6 +461,9 @@ func (cli *DockerCli) CmdInfo(args ...string) error {
 	fmt.Fprintf(cli.out, "Containers: %d\n", out.Containers)
 	fmt.Fprintf(cli.out, "Images: %d\n", out.Images)
 	fmt.Fprintf(cli.out, "Driver: %s\n", out.Driver)
+	for _, pair := range out.DriverStatus {
+		fmt.Fprintf(cli.out, " %s: %s\n", pair[0], pair[1])
+	}
 	if out.Debug || os.Getenv("DEBUG") != "" {
 		fmt.Fprintf(cli.out, "Debug mode (server): %v\n", out.Debug)
 		fmt.Fprintf(cli.out, "Debug mode (client): %v\n", os.Getenv("DEBUG") != "")

devmapper/driver.go

@@ -37,6 +37,21 @@ func (d *Driver) String() string {
 	return "devicemapper"
 }
 
+func (d *Driver) Status() [][2]string {
+	s := d.DeviceSet.Status()
+
+	status := [][2]string{
+		{"Pool Name", s.PoolName},
+		{"Data file", s.DataLoopback},
+		{"Metadata file", s.MetadataLoopback},
+		{"Data Space Used", fmt.Sprintf("%.1f Mb", float64(s.Data.Used)/(1024*1024))},
+		{"Data Space Total", fmt.Sprintf("%.1f Mb", float64(s.Data.Total)/(1024*1024))},
+		{"Metadata Space Used", fmt.Sprintf("%.1f Mb", float64(s.Metadata.Used)/(1024*1024))},
+		{"Metadata Space Total", fmt.Sprintf("%.1f Mb", float64(s.Metadata.Total)/(1024*1024))},
+	}
+	return status
+}
+
 func (d *Driver) Cleanup() error {
 	return d.DeviceSet.Shutdown()
 }

graphdriver/driver.go

@@ -19,6 +19,8 @@ type Driver interface {
 	Get(id string) (dir string, err error)
 	Size(id string) (bytes int64, err error)
 
+	Status() [][2]string
+
 	Cleanup() error
 }
 

graphdriver/dummy/driver.go

@@ -27,6 +27,10 @@ func (d *Driver) String() string {
 	return "dummy"
 }
 
+func (d *Driver) Status() [][2]string {
+	return nil
+}
+
 func (d *Driver) Cleanup() error {
 	return nil
 }

server.go

@@ -376,6 +376,7 @@ func (srv *Server) DockerInfo() *APIInfo {
 		Containers:         len(srv.runtime.List()),
 		Images:             imgcount,
 		Driver:             srv.runtime.driver.String(),
+		DriverStatus:       srv.runtime.driver.Status(),
 		MemoryLimit:        srv.runtime.capabilities.MemoryLimit,
 		SwapLimit:          srv.runtime.capabilities.SwapLimit,
 		IPv4Forwarding:     !srv.runtime.capabilities.IPv4ForwardingDisabled,