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|
package cgroups
import (
"fmt"
"os"
"path/filepath"
"strconv"
)
type rawCgroup struct {
root string
cgroup string
}
func rawApply(c *Cgroup, pid int) (ActiveCgroup, error) {
// We have two implementation of cgroups support, one is based on
// systemd and the dbus api, and one is based on raw cgroup fs operations
// following the pre-single-writer model docs at:
// http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups/
//
// we can pick any subsystem to find the root
cgroupRoot, err := FindCgroupMountpoint("cpu")
if err != nil {
return nil, err
}
cgroupRoot = filepath.Dir(cgroupRoot)
if _, err := os.Stat(cgroupRoot); err != nil {
return nil, fmt.Errorf("cgroups fs not found")
}
cgroup := c.Name
if c.Parent != "" {
cgroup = filepath.Join(c.Parent, cgroup)
}
raw := &rawCgroup{
root: cgroupRoot,
cgroup: cgroup,
}
if err := raw.setupDevices(c, pid); err != nil {
return nil, err
}
if err := raw.setupMemory(c, pid); err != nil {
return nil, err
}
if err := raw.setupCpu(c, pid); err != nil {
return nil, err
}
if err := raw.setupCpuset(c, pid); err != nil {
return nil, err
}
return raw, nil
}
func (raw *rawCgroup) path(subsystem string) (string, error) {
initPath, err := GetInitCgroupDir(subsystem)
if err != nil {
return "", err
}
return filepath.Join(raw.root, subsystem, initPath, raw.cgroup), nil
}
func (raw *rawCgroup) join(subsystem string, pid int) (string, error) {
path, err := raw.path(subsystem)
if err != nil {
return "", err
}
if err := os.MkdirAll(path, 0755); err != nil && !os.IsExist(err) {
return "", err
}
if err := writeFile(path, "cgroup.procs", strconv.Itoa(pid)); err != nil {
return "", err
}
return path, nil
}
func (raw *rawCgroup) setupDevices(c *Cgroup, pid int) (err error) {
if !c.DeviceAccess {
dir, err := raw.join("devices", pid)
if err != nil {
return err
}
defer func() {
if err != nil {
os.RemoveAll(dir)
}
}()
if err := writeFile(dir, "devices.deny", "a"); err != nil {
return err
}
allow := []string{
// allow mknod for any device
"c *:* m",
"b *:* m",
// /dev/null, zero, full
"c 1:3 rwm",
"c 1:5 rwm",
"c 1:7 rwm",
// consoles
"c 5:1 rwm",
"c 5:0 rwm",
"c 4:0 rwm",
"c 4:1 rwm",
// /dev/urandom,/dev/random
"c 1:9 rwm",
"c 1:8 rwm",
// /dev/pts/ - pts namespaces are "coming soon"
"c 136:* rwm",
"c 5:2 rwm",
// tuntap
"c 10:200 rwm",
}
for _, val := range allow {
if err := writeFile(dir, "devices.allow", val); err != nil {
return err
}
}
}
return nil
}
func (raw *rawCgroup) setupMemory(c *Cgroup, pid int) (err error) {
if c.Memory != 0 || c.MemorySwap != 0 {
dir, err := raw.join("memory", pid)
if err != nil {
return err
}
defer func() {
if err != nil {
os.RemoveAll(dir)
}
}()
if c.Memory != 0 {
if err := writeFile(dir, "memory.limit_in_bytes", strconv.FormatInt(c.Memory, 10)); err != nil {
return err
}
if err := writeFile(dir, "memory.soft_limit_in_bytes", strconv.FormatInt(c.Memory, 10)); err != nil {
return err
}
}
// By default, MemorySwap is set to twice the size of RAM.
// If you want to omit MemorySwap, set it to `-1'.
if c.MemorySwap != -1 {
if err := writeFile(dir, "memory.memsw.limit_in_bytes", strconv.FormatInt(c.Memory*2, 10)); err != nil {
return err
}
}
}
return nil
}
func (raw *rawCgroup) setupCpu(c *Cgroup, pid int) (err error) {
// We always want to join the cpu group, to allow fair cpu scheduling
// on a container basis
dir, err := raw.join("cpu", pid)
if err != nil {
return err
}
if c.CpuShares != 0 {
if err := writeFile(dir, "cpu.shares", strconv.FormatInt(c.CpuShares, 10)); err != nil {
return err
}
}
return nil
}
func (raw *rawCgroup) setupCpuset(c *Cgroup, pid int) (err error) {
if c.CpusetCpus != "" {
dir, err := raw.join("cpuset", pid)
if err != nil {
return err
}
defer func() {
if err != nil {
os.RemoveAll(dir)
}
}()
if err := writeFile(dir, "cpuset.cpus", c.CpusetCpus); err != nil {
return err
}
}
return nil
}
func (raw *rawCgroup) Cleanup() error {
get := func(subsystem string) string {
path, _ := raw.path(subsystem)
return path
}
for _, path := range []string{
get("memory"),
get("devices"),
get("cpu"),
get("cpuset"),
} {
if path != "" {
os.RemoveAll(path)
}
}
return nil
}
|
