Created a global runtime checkpoint for libcontainer. Got rid of the network specific runtime checkpoint.

Docker-DCO-1.1-Signed-off-by: Vishnu Kannan <vishnuk@google.com> (github: vishh)

api.go

@@ -1,21 +1,19 @@
-package api
+package libcontainer
 
 import (
-	"github.com/docker/libcontainer"
 	"github.com/docker/libcontainer/cgroups/fs"
-
 	"github.com/docker/libcontainer/network"
 )
 
 // Returns all available stats for the given container.
-func GetContainerStats(container *libcontainer.Container, networkInfo *network.NetworkRuntimeInfo) (*ContainerStats, error) {
+func GetContainerStats(container *Config, runtimeCkpt *RuntimeCkpt) (*ContainerStats, error) {
 	containerStats := NewContainerStats()
 	stats, err := fs.GetStats(container.Cgroups)
 	if err != nil {
 		return containerStats, err
 	}
 	containerStats.CgroupStats = stats
-	networkStats, err := network.GetStats(networkInfo)
+	networkStats, err := network.GetStats(&runtimeCkpt.NetworkCkpt)
 	if err != nil {
 		return containerStats, err
 	}

checkpoint.go

@@ -0,0 +1,65 @@
+package libcontainer
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/docker/libcontainer/network"
+)
+
+// A checkpoint struct that will contain all runtime checkpointed information.
+type RuntimeCkpt struct {
+	NetworkCkpt network.NetworkCkpt `json:"network_ckpt,omitempty"`
+}
+
+// The name of the network checkpoint file
+const runtimeCkptFile = "runtimeCkpt.json"
+
+var ErrRuntimeCkptNotFound = errors.New("Runtime Checkpoint not found")
+
+// Returns the path to the network checkpoint given the path to the base directory of network checkpoint.
+func getRuntimeCkptPath(basePath string) string {
+	return filepath.Join(basePath, runtimeCkptFile)
+}
+
+// Updates the Runtime Checkpoint with current checkpoint information from all the subsystems.
+func UpdateRuntimeCkpt(basePath string) error {
+	runtimeCkpt := &RuntimeCkpt{
+		NetworkCkpt: *network.NetworkCkptImpl.GetNetworkCkpt(),
+	}
+	data, err := json.Marshal(runtimeCkpt)
+	if err != nil {
+		return fmt.Errorf("Failed to checkpoint runtime information - %s", err)
+	}
+	return ioutil.WriteFile(getRuntimeCkptPath(basePath), data, 0655)
+}
+
+// Loads and returns the rutime checkpointing existing inside basePath. Returns ErrRuntimeCkptNotFound
+// if the runtime checkpoint does not exist.
+func GetRuntimeCkpt(basePath string) (*RuntimeCkpt, error) {
+	runtimeCkpt := &RuntimeCkpt{}
+	checkpointPath := getRuntimeCkptPath(basePath)
+	f, err := os.Open(checkpointPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return runtimeCkpt, ErrRuntimeCkptNotFound
+		}
+		return runtimeCkpt, err
+	}
+	defer f.Close()
+
+	if err := json.NewDecoder(f).Decode(runtimeCkpt); err != nil {
+		return runtimeCkpt, err
+	}
+
+	return runtimeCkpt, nil
+}
+
+// Deletes the runtime checkpoint under basePath
+func DeleteNetworkRuntimeInfo(basePath string) error {
+	return os.Remove(getRuntimeCkptPath(basePath))
+}

namespaces/exec.go

@@ -87,6 +87,13 @@ func Exec(container *libcontainer.Config, term Terminal, rootfs, dataPath string
 		return -1, err
 	}
 
+	// Update the runtime checkpoint.
+	if err = libcontainer.UpdateRuntimeCkpt(dataPath); err != nil {
+		command.Process.Kill()
+		command.Wait()
+		return -1, err
+	}
+
 	// Sync with child
 	syncPipe.Close()
 

network/checkpoint.go

@@ -1,63 +1,25 @@
 package network
 
-import (
-	"encoding/json"
-	"errors"
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path/filepath"
-)
-
 // Struct describing the network specific checkpoint that will be maintained by libcontainer for all running containers
 // This is an internal checkpoint, so do not depend on it outside of libcontainer.
-type NetworkRuntimeInfo struct {
+type NetworkCkpt struct {
 	// The name of the veth interface on the Host.
 	VethHost string `json:"veth_host,omitempty"`
 	// The name of the veth interface created inside the container for the child.
 	VethChild string `json:"veth_child,omitempty"`
 }
 
-// The name of the network checkpoint file
-const networkInfoFile = "network.json"
+type NetworkCkptIntImpl struct{}
 
-var ErrNetworkRuntimeInfoNotFound = errors.New("Network Checkpoint not found")
+var (
+	networkCkptInfo = &NetworkCkpt{}
+	NetworkCkptImpl = &NetworkCkptIntImpl{}
+)
 
-// Returns the path to the network checkpoint given the path to the base directory of network checkpoint.
-func getNetworkRuntimeInfoPath(basePath string) string {
-	return filepath.Join(basePath, networkInfoFile)
+func (NetworkCkptIntImpl) GetNetworkCkpt() *NetworkCkpt {
+	return networkCkptInfo
 }
 
-// Marshalls the input network runtime info struct into a json object and stores it inside basepath.
-func writeNetworkRuntimeInfo(networkInfo *NetworkRuntimeInfo, basePath string) error {
-	data, err := json.Marshal(networkInfo)
-	if err != nil {
-		return fmt.Errorf("Failed to checkpoint network runtime information - %s", err)
-	}
-	return ioutil.WriteFile(getNetworkRuntimeInfoPath(basePath), data, 0655)
-}
-
-// Loads the network runtime info from the checkpoint and returns the unmarshaled content.
-func LoadNetworkRuntimeInfo(basePath string) (NetworkRuntimeInfo, error) {
-	var networkRuntimeInfo NetworkRuntimeInfo
-	checkpointPath := getNetworkRuntimeInfoPath(basePath)
-	f, err := os.Open(checkpointPath)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return networkRuntimeInfo, ErrNetworkRuntimeInfoNotFound
-		}
-		return networkRuntimeInfo, err
-	}
-	defer f.Close()
-
-	if err := json.NewDecoder(f).Decode(&networkRuntimeInfo); err != nil {
-		return networkRuntimeInfo, err
-	}
-
-	return networkRuntimeInfo, nil
-}
-
-// Deletes the network checkpoint under basePath
-func deleteNetworkRuntimeInfo(basePath string) error {
-	return os.Remove(getNetworkRuntimeInfoPath(basePath))
+func (NetworkCkptIntImpl) updateNetworkCkpt(n *NetworkCkpt) {
+	networkCkptInfo = n
 }

network/stats.go

@@ -20,12 +20,12 @@ type NetworkStats struct {
 }
 
 // Returns the network statistics for the network interfaces represented by the NetworkRuntimeInfo.
-func GetStats(networkRuntimeInfo *NetworkRuntimeInfo) (NetworkStats, error) {
+func GetStats(networkCkpt *NetworkCkpt) (NetworkStats, error) {
 	// This can happen if the network runtime information is missing - possible if the container was created by an old version of libcontainer.
-	if networkRuntimeInfo.VethHost == "" {
+	if networkCkpt.VethHost == "" {
 		return NetworkStats{}, nil
 	}
-	data, err := readSysfsNetworkStats(networkRuntimeInfo.VethHost)
+	data, err := readSysfsNetworkStats(networkCkpt.VethHost)
 	if err != nil {
 		return NetworkStats{}, err
 	}

network/veth.go

@@ -45,8 +45,11 @@ func (v *Veth) Create(n *Network, nspid int, context map[string]string, dataPath
 	if err := SetInterfaceInNamespacePid(name2, nspid); err != nil {
 		return err
 	}
-	networkRuntimeInfo := NetworkRuntimeInfo{VethHost: name1, VethChild: name2}
-	return writeNetworkRuntimeInfo(&networkRuntimeInfo, dataPath)
+	networkCkpt := NetworkCkptImpl.GetNetworkCkpt()
+	networkCkpt.VethHost = name1
+	networkCkpt.VethChild = name2
+	NetworkCkptImpl.updateNetworkCkpt(networkCkpt)
+	return nil
 }
 
 func (v *Veth) Initialize(config *Network, context map[string]string) error {

nsinit/stats.go

@@ -7,8 +7,6 @@ import (
 
 	"github.com/codegangsta/cli"
 	"github.com/docker/libcontainer"
-	"github.com/docker/libcontainer/api"
-	"github.com/docker/libcontainer/network"
 )
 
 var statsCommand = cli.Command{
@@ -23,12 +21,12 @@ func statsAction(context *cli.Context) {
 		log.Fatal(err)
 	}
 
-	networkRuntimeInfo, err := loadNetworkRuntimeInfo()
+	runtimeCkpt, err := libcontainer.GetRuntimeCkpt(dataPath)
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	stats, err := getContainerStats(container, &networkRuntimeInfo)
+	stats, err := getContainerStats(container, runtimeCkpt)
 	if err != nil {
 		log.Fatalf("Failed to get stats - %v\n", err)
 	}
@@ -37,8 +35,8 @@ func statsAction(context *cli.Context) {
 }
 
 // returns the container stats in json format.
-func getContainerStats(container *libcontainer.Config, networkRuntimeInfo *network.NetworkRuntimeInfo) (string, error) {
-	stats, err := libcontainer.GetContainerStats(container, networkRuntimeInfo)
+func getContainerStats(container *libcontainer.Config, runtimeCkpt *libcontainer.RuntimeCkpt) (string, error) {
+	stats, err := libcontainer.GetContainerStats(container, runtimeCkpt)
 	if err != nil {
 		return "", err
 	}

nsinit/utils.go

@@ -7,7 +7,6 @@ import (
 	"path/filepath"
 
 	"github.com/docker/libcontainer"
-	"github.com/docker/libcontainer/network"
 )
 
 func loadContainer() (*libcontainer.Config, error) {
@@ -25,17 +24,6 @@ func loadContainer() (*libcontainer.Config, error) {
 	return container, nil
 }
 
-func loadNetworkRuntimeInfo() (network.NetworkRuntimeInfo, error) {
-	data, err := network.LoadNetworkRuntimeInfo(dataPath)
-	if err != nil {
-		if err == network.ErrNetworkRuntimeInfoNotFound {
-			return network.NetworkRuntimeInfo{}, nil
-		}
-		return network.NetworkRuntimeInfo{}, err
-	}
-	return data, nil
-}
-
 func openLog(name string) error {
 	f, err := os.OpenFile(name, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0755)
 	if err != nil {

types.go

@@ -1,4 +1,4 @@
-package api
+package libcontainer
 
 import (
 	"github.com/docker/libcontainer/cgroups"