Removed NotActive error message from container package.

Imporved error messages.

container/container.go

@@ -14,11 +14,7 @@
 
 package container
 
-import (
-	"errors"
-
-	"github.com/google/cadvisor/info"
-)
+import "github.com/google/cadvisor/info"
 
 // Listing types.
 const (
@@ -26,8 +22,6 @@ const (
 	LIST_RECURSIVE
 )
 
-var NotActive = errors.New("Container is not active")
-
 type ListType int
 
 // Interface for container operation handlers.

container/docker/factory.go

@@ -28,16 +28,15 @@ import (
 	"github.com/google/cadvisor/info"
 )
 
-var (
-	ArgDockerEndpoint = flag.String("docker", "unix:///var/run/docker.sock", "docker endpoint")
-	defaultClient     *docker.Client
-)
+var ArgDockerEndpoint = flag.String("docker", "unix:///var/run/docker.sock", "docker endpoint")
 
 type dockerFactory struct {
 	machineInfoFactory info.MachineInfoFactory
 
 	// Whether this system is using systemd.
 	useSystemd bool
+
+	client *docker.Client
 }
 
 func (self *dockerFactory) String() string {
@@ -77,10 +76,7 @@ func (self *dockerFactory) CanHandle(name string) bool {
 	if err != nil {
 		return false
 	}
-	if defaultClient == nil {
-		log.Fatal("Default docker client is nil")
-	}
-	ctnr, err := defaultClient.InspectContainer(id)
+	ctnr, err := self.client.InspectContainer(id)
 	// We assume that if Inspect fails then the container is not known to docker.
 	// TODO(vishh): Detect lxc containers and avoid handling them.
 	if err != nil || !ctnr.State.Running {
@@ -110,12 +106,12 @@ func parseDockerVersion(full_version_string string) ([]int, error) {
 }
 
 // Register root container before running this function!
-func Register(factory info.MachineInfoFactory) (err error) {
-	defaultClient, err = docker.NewClient(*ArgDockerEndpoint)
+func Register(factory info.MachineInfoFactory) error {
+	client, err := docker.NewClient(*ArgDockerEndpoint)
 	if err != nil {
 		return fmt.Errorf("unable to communicate with docker daemon: %v", err)
 	}
-	if version, err := defaultClient.Version(); err != nil {
+	if version, err := client.Version(); err != nil {
 		return fmt.Errorf("unable to communicate with docker daemon: %v", err)
 	} else {
 		expected_version := []int{0, 11, 1}
@@ -135,6 +131,7 @@ func Register(factory info.MachineInfoFactory) (err error) {
 	f := &dockerFactory{
 		machineInfoFactory: factory,
 		useSystemd:         systemd.UseSystemd(),
+		client:             client,
 	}
 	log.Printf("Registering Docker factory")
 	container.RegisterContainerHandlerFactory(f)

container/docker/handler.go

@@ -71,8 +71,8 @@ func newDockerContainerHandler(
 	handler.ID = id
 	ctnr, err := client.InspectContainer(id)
 	// We assume that if Inspect fails then the container is not known to docker.
-	if err != nil || !ctnr.State.Running {
-		return nil, container.NotActive
+	if err != nil {
+		return nil, fmt.Errorf("failed to inspect container %s - %s\n", id, err)
 	}
 	handler.aliases = append(handler.aliases, path.Join("/docker", ctnr.Name))
 	return handler, nil
@@ -126,16 +126,17 @@ func splitName(containerName string) (string, string, error) {
 	return parent, id, nil
 }
 
-// TODO(vmarmol): Switch to getting this from libcontainer once we have a solID API.
+// TODO(vmarmol): Switch to getting this from libcontainer once we have a solid API.
 func (self *dockerContainerHandler) readLibcontainerConfig() (config *libcontainer.Config, err error) {
 	configPath := path.Join(dockerRootDir, self.ID, "container.json")
 	if !utils.FileExists(configPath) {
+		// TODO(vishh): Return file name as well once we have a better error interface.
 		err = fileNotFound
 		return
 	}
 	f, err := os.Open(configPath)
 	if err != nil {
-		return
+		return nil, fmt.Errorf("failed to open %s - %s\n", configPath, err)
 	}
 	defer f.Close()
 	d := json.NewDecoder(f)
@@ -152,15 +153,13 @@ func (self *dockerContainerHandler) readLibcontainerConfig() (config *libcontain
 func (self *dockerContainerHandler) readLibcontainerState() (state *libcontainer.State, err error) {
 	statePath := path.Join(dockerRootDir, self.ID, "state.json")
 	if !utils.FileExists(statePath) {
+		// TODO(vishh): Return file name as well once we have a better error interface.
 		err = fileNotFound
 		return
 	}
 	f, err := os.Open(statePath)
 	if err != nil {
-		if os.IsNotExist(err) {
-			err = container.NotActive
-		}
-		return
+		return nil, fmt.Errorf("failed to open %s - %s\n", statePath, err)
 	}
 	defer f.Close()
 	d := json.NewDecoder(f)

container/lmctfy/factory.go

@@ -49,7 +49,6 @@ func (self *lmctfyFactory) NewContainerHandler(name string) (container.Container
 }
 
 func (self *lmctfyFactory) CanHandle(name string) bool {
-	// TODO(vmarmol): Try to attach to the container before blindly saying true.
 	cmd := exec.Command(lmctfyBinary, "stats", "summary", name)
 	_, err := cmd.Output()
 	if err != nil {

manager/container.go

@@ -127,7 +127,7 @@ func (c *containerData) housekeeping() {
 
 func (c *containerData) housekeepingTick() {
 	err := c.updateStats()
-	if err != nil && err != container.NotActive {
+	if err != nil {
 		log.Printf("Failed to update stats for container \"%s\": %s", c.info.Name, err)
 	}
 }

manager/manager.go

@@ -284,9 +284,7 @@ func (m *manager) detectContainers() error {
 	for _, cont := range added {
 		_, err = m.createContainer(cont.Name)
 		if err != nil {
-			if err != container.NotActive {
-				log.Printf("failed to create existing container: %s: %s", cont.Name, err)
-			}
+			log.Printf("failed to create existing container: %s: %s", cont.Name, err)
 		}
 	}
 
@@ -294,9 +292,7 @@ func (m *manager) detectContainers() error {
 	for _, cont := range removed {
 		err = m.destroyContainer(cont.Name)
 		if err != nil {
-			if err != container.NotActive {
-				log.Printf("failed to destroy existing container: %s: %s", cont.Name, err)
-			}
+			log.Printf("failed to destroy existing container: %s: %s", cont.Name, err)
 		}
 	}