Handle out of disk situation on kubelets.

Kubelet will stop accepting new pods if it detects low disk space on root fs or fs holding docker images.
Running pods are not affected. low-diskspace-threshold-mb is used to configure the low diskspace threshold.

pkg/kubelet/cadvisor/cadvisor_fake.go

@@ -52,6 +52,10 @@ func (c *Fake) DockerImagesFsInfo() (cadvisorApiV2.FsInfo, error) {
 	return cadvisorApiV2.FsInfo{}, nil
 }
 
+func (c *Fake) RootFsInfo() (cadvisorApiV2.FsInfo, error) {
+	return cadvisorApiV2.FsInfo{}, nil
+}
+
 func (c *Fake) WatchEvents(request *events.Request) (*events.EventChannel, error) {
 	return new(events.EventChannel), nil
 }

pkg/kubelet/cadvisor/cadvisor_linux.go

@@ -132,16 +132,24 @@ func (cc *cadvisorClient) MachineInfo() (*cadvisorApi.MachineInfo, error) {
 }
 
 func (cc *cadvisorClient) DockerImagesFsInfo() (cadvisorApiV2.FsInfo, error) {
-	res, err := cc.GetFsInfo(cadvisorFs.LabelDockerImages)
+	return cc.getFsInfo(cadvisorFs.LabelDockerImages)
+}
+
+func (cc *cadvisorClient) RootFsInfo() (cadvisorApiV2.FsInfo, error) {
+	return cc.getFsInfo(cadvisorFs.LabelSystemRoot)
+}
+
+func (cc *cadvisorClient) getFsInfo(label string) (cadvisorApiV2.FsInfo, error) {
+	res, err := cc.GetFsInfo(label)
 	if err != nil {
 		return cadvisorApiV2.FsInfo{}, err
 	}
 	if len(res) == 0 {
-		return cadvisorApiV2.FsInfo{}, fmt.Errorf("failed to find information for the filesystem containing Docker images")
+		return cadvisorApiV2.FsInfo{}, fmt.Errorf("failed to find information for the filesystem labeled %q", label)
 	}
-	// TODO(vmarmol): Handle this better when Docker has more than one image filesystem.
+	// TODO(vmarmol): Handle this better when a label has more than one image filesystem.
 	if len(res) > 1 {
-		glog.Warningf("More than one Docker images filesystem: %#v. Only using the first one", res)
+		glog.Warningf("More than one filesystem labeled %q: %#v. Only using the first one", label, res)
 	}
 
 	return res[0], nil

pkg/kubelet/cadvisor/cadvisor_mock.go

@@ -62,6 +62,11 @@ func (c *Mock) DockerImagesFsInfo() (cadvisorApiV2.FsInfo, error) {
 	return args.Get(0).(cadvisorApiV2.FsInfo), args.Error(1)
 }
 
+func (c *Mock) RootFsInfo() (cadvisorApiV2.FsInfo, error) {
+	args := c.Called()
+	return args.Get(0).(cadvisorApiV2.FsInfo), args.Error(1)
+}
+
 func (c *Mock) WatchEvents(request *events.Request) (*events.EventChannel, error) {
 	args := c.Called()
 	return args.Get(0).(*events.EventChannel), args.Error(1)

pkg/kubelet/cadvisor/cadvisor_unsupported.go

@@ -61,6 +61,10 @@ func (cu *cadvisorUnsupported) DockerImagesFsInfo() (cadvisorApiV2.FsInfo, error
 	return cadvisorApiV2.FsInfo{}, unsupportedErr
 }
 
+func (cu *cadvisorUnsupported) RootFsInfo() (cadvisorApiV2.FsInfo, error) {
+	return cadvisorApiV2.FsInfo{}, unsupportedErr
+}
+
 func (cu *cadvisorUnsupported) WatchEvents(request *events.Request) (*events.EventChannel, error) {
 	return nil, unsupportedErr
 }

pkg/kubelet/cadvisor/types.go

@@ -34,6 +34,9 @@ type Interface interface {
 	// Returns usage information about the filesystem holding Docker images.
 	DockerImagesFsInfo() (cadvisorApiV2.FsInfo, error)
 
+	// Returns usage information about the root filesystem.
+	RootFsInfo() (cadvisorApiV2.FsInfo, error)
+
 	// Get events streamed through passedChannel that fit the request.
 	WatchEvents(request *events.Request) (*events.EventChannel, error)
 }