Merge pull request #253 from avagin/cr-cgroups

c/r: create cgroups to restore a container

libcontainer/cgroups/cgroups_test.go

@@ -3,27 +3,16 @@
 package cgroups
 
 import (
-	"bytes"
 	"testing"
 )
 
-const (
-	cgroupsContents = `11:hugetlb:/
-10:perf_event:/
-9:blkio:/
-8:net_cls:/
-7:freezer:/
-6:devices:/
-5:memory:/
-4:cpuacct,cpu:/
-3:cpuset:/
-2:name=systemd:/user.slice/user-1000.slice/session-16.scope`
-)
-
 func TestParseCgroups(t *testing.T) {
-	r := bytes.NewBuffer([]byte(cgroupsContents))
+	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
-	_, err := ParseCgroupFile("blkio", r)
 	if err != nil {
 		t.Fatal(err)
 	}
+
+	if _, ok := cgroups["cpu"]; !ok {
+		t.Fail()
+	}
 }

libcontainer/cgroups/utils.go

@@ -5,7 +5,6 @@ package cgroups
 import (
 	"bufio"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -105,12 +104,12 @@ type Mount struct {
 	Subsystems []string
 }
 
-func (m Mount) GetThisCgroupDir() (string, error) {
+func (m Mount) GetThisCgroupDir(cgroups map[string]string) (string, error) {
 	if len(m.Subsystems) == 0 {
 		return "", fmt.Errorf("no subsystem for mount")
 	}
 
-	return GetThisCgroupDir(m.Subsystems[0])
+	return getControllerPath(m.Subsystems[0], cgroups)
 }
 
 func GetCgroupMounts() ([]Mount, error) {
@@ -176,23 +175,22 @@ func GetAllSubsystems() ([]string, error) {
 
 // Returns the relative path to the cgroup docker is running in.
 func GetThisCgroupDir(subsystem string) (string, error) {
-	f, err := os.Open("/proc/self/cgroup")
+	cgroups, err := ParseCgroupFile("/proc/self/cgroup")
 	if err != nil {
 		return "", err
 	}
-	defer f.Close()
 
-	return ParseCgroupFile(subsystem, f)
+	return getControllerPath(subsystem, cgroups)
 }
 
 func GetInitCgroupDir(subsystem string) (string, error) {
-	f, err := os.Open("/proc/1/cgroup")
+
+	cgroups, err := ParseCgroupFile("/proc/1/cgroup")
 	if err != nil {
 		return "", err
 	}
-	defer f.Close()
 
-	return ParseCgroupFile(subsystem, f)
+	return getControllerPath(subsystem, cgroups)
 }
 
 func ReadProcsFile(dir string) ([]int, error) {
@@ -219,23 +217,40 @@ func ReadProcsFile(dir string) ([]int, error) {
 	return out, nil
 }
 
-func ParseCgroupFile(subsystem string, r io.Reader) (string, error) {
+func ParseCgroupFile(path string) (map[string]string, error) {
-	s := bufio.NewScanner(r)
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	s := bufio.NewScanner(f)
+	cgroups := make(map[string]string)
 
 	for s.Scan() {
 		if err := s.Err(); err != nil {
-			return "", err
+			return nil, err
 		}
 
 		text := s.Text()
 		parts := strings.Split(text, ":")
 
 		for _, subs := range strings.Split(parts[1], ",") {
-			if subs == subsystem || subs == cgroupNamePrefix+subsystem {
+			cgroups[subs] = parts[2]
-				return parts[2], nil
-			}
 		}
 	}
+	return cgroups, nil
+}
+
+func getControllerPath(subsystem string, cgroups map[string]string) (string, error) {
+
+	if p, ok := cgroups[subsystem]; ok {
+		return p, nil
+	}
+
+	if p, ok := cgroups[cgroupNamePrefix+subsystem]; ok {
+		return p, nil
+	}
 
 	return "", NewNotFoundError(subsystem)
 }

libcontainer/container_linux.go

@@ -423,7 +423,7 @@ func (c *linuxContainer) Checkpoint(criuOpts *CriuOpts) error {
 		return err
 	}
 
-	err = c.criuSwrk(nil, req, criuOpts)
+	err = c.criuSwrk(nil, req, criuOpts, false)
 	if err != nil {
 		return err
 	}
@@ -516,6 +516,7 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 			FileLocks:      proto.Bool(criuOpts.FileLocks),
 		},
 	}
+
 	for _, m := range c.config.Mounts {
 		switch m.Device {
 		case "bind":
@@ -573,14 +574,36 @@ func (c *linuxContainer) Restore(process *Process, criuOpts *CriuOpts) error {
 		}
 	}
 
-	err = c.criuSwrk(process, req, criuOpts)
+	err = c.criuSwrk(process, req, criuOpts, true)
 	if err != nil {
 		return err
 	}
 	return nil
 }
 
-func (c *linuxContainer) criuSwrk(process *Process, req *criurpc.CriuReq, opts *CriuOpts) error {
+func (c *linuxContainer) criuApplyCgroups(pid int, req *criurpc.CriuReq) error {
+	if err := c.cgroupManager.Apply(pid); err != nil {
+		return err
+	}
+
+	path := fmt.Sprintf("/proc/%d/cgroup", pid)
+	cgroupsPaths, err := cgroups.ParseCgroupFile(path)
+	if err != nil {
+		return err
+	}
+
+	for c, p := range cgroupsPaths {
+		cgroupRoot := &criurpc.CgroupRoot{
+			Ctrl: proto.String(c),
+			Path: proto.String(p),
+		}
+		req.Opts.CgRoot = append(req.Opts.CgRoot, cgroupRoot)
+	}
+
+	return nil
+}
+
+func (c *linuxContainer) criuSwrk(process *Process, req *criurpc.CriuReq, opts *CriuOpts, applyCgroups bool) error {
 	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_SEQPACKET|syscall.SOCK_CLOEXEC, 0)
 	if err != nil {
 		return err
@@ -614,6 +637,13 @@ func (c *linuxContainer) criuSwrk(process *Process, req *criurpc.CriuReq, opts *
 		}
 	}()
 
+	if applyCgroups {
+		err := c.criuApplyCgroups(cmd.Process.Pid, req)
+		if err != nil {
+			return err
+		}
+	}
+
 	var extFds []string
 	if process != nil {
 		extFds, err = getPipeFds(cmd.Process.Pid)

libcontainer/rootfs_linux.go

@@ -253,10 +253,15 @@ func getCgroupMounts(m *configs.Mount) ([]*configs.Mount, error) {
 		return nil, err
 	}
 
+	cgroupPaths, err := cgroups.ParseCgroupFile("/proc/self/cgroup")
+	if err != nil {
+		return nil, err
+	}
+
 	var binds []*configs.Mount
 
 	for _, mm := range mounts {
-		dir, err := mm.GetThisCgroupDir()
+		dir, err := mm.GetThisCgroupDir(cgroupPaths)
 		if err != nil {
 			return nil, err
 		}