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Merge pull request #583 from alexlarsson/conmon-reap-zombies

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conmon: Don't leave zombies and fix cgroup race
This commit is contained in:
Mrunal Patel 2017-06-20 07:53:52 -07:00 • committed by GitHub
commit 88037b143b
3 changed files with 121 additions and 82 deletions
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48
oci/oci.go
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@ -128,10 +128,12 @@ func getOCIVersion(name string, args ...string) (string, error) {
func (r *Runtime) CreateContainer(c *Container, cgroupParent string) error {
var stderrBuf bytes.Buffer
parentPipe, childPipe, err := newPipe()
childStartPipe, parentStartPipe, err := newPipe()
if err != nil {
return fmt.Errorf("error creating socket pair: %v", err)
}
defer parentPipe.Close()
defer parentStartPipe.Close()
var args []string
if r.cgroupManager == "systemd" {
@ -163,9 +165,10 @@ func (r *Runtime) CreateContainer(c *Container, cgroupParent string) error {
if c.terminal {
cmd.Stderr = &stderrBuf
}
cmd.ExtraFiles = append(cmd.ExtraFiles, childPipe)
cmd.ExtraFiles = append(cmd.ExtraFiles, childPipe, childStartPipe)
// 0, 1 and 2 are stdin, stdout and stderr
cmd.Env = append(r.conmonEnv, fmt.Sprintf("_OCI_SYNCPIPE=%d", 3))
cmd.Env = append(cmd.Env, fmt.Sprintf("_OCI_STARTPIPE=%d", 4))
err = cmd.Start()
if err != nil {
@ -175,6 +178,7 @@ func (r *Runtime) CreateContainer(c *Container, cgroupParent string) error {
// We don't need childPipe on the parent side
childPipe.Close()
childStartPipe.Close()
// Move conmon to specified cgroup
if cgroupParent != "" {
@ -186,6 +190,19 @@ func (r *Runtime) CreateContainer(c *Container, cgroupParent string) error {
}
}
/* We set the cgroup, now the child can start creating children */
someData := []byte{0}
_, err = parentStartPipe.Write(someData)
if err != nil {
return err
}
/* Wait for initial setup and fork, and reap child */
err = cmd.Wait()
if err != nil {
return err
}
// Wait to get container pid from conmon
type syncStruct struct {
si *syncInfo
@ -207,21 +224,10 @@ func (r *Runtime) CreateContainer(c *Container, cgroupParent string) error {
return fmt.Errorf("error reading container (probably exited) json message: %v", ss.err)
}
logrus.Debugf("Received container pid: %d", ss.si.Pid)
errorMessage := ""
if c.terminal {
errorMessage = stderrBuf.String()
fmt.Fprintf(os.Stderr, errorMessage)
errorMessage = sanitizeConmonErrorMessage(errorMessage)
} else {
if ss.si.Message != "" {
errorMessage = ss.si.Message
}
}
if ss.si.Pid == -1 {
if errorMessage != "" {
logrus.Debugf("Container creation error: %s", errorMessage)
return fmt.Errorf("container create failed: %s", errorMessage)
if ss.si.Message != "" {
logrus.Debugf("Container creation error: %s", ss.si.Message)
return fmt.Errorf("container create failed: %s", ss.si.Message)
}
logrus.Debugf("Container creation failed")
return fmt.Errorf("container create failed")
@ -232,18 +238,6 @@ func (r *Runtime) CreateContainer(c *Container, cgroupParent string) error {
return nil
}
// sanitizeConmonErrorMessage removes conmon debug messages from error string
func sanitizeConmonErrorMessage(errString string) string {
var sanitizedLines []string
lines := strings.Split(errString, "\n")
for _, line := range lines {
if !strings.HasPrefix(line, "[conmon") {
sanitizedLines = append(sanitizedLines, line)
}
}
return strings.Join(sanitizedLines, "\n")
}
func createUnitName(prefix string, name string) string {
return fmt.Sprintf("%s-%s.scope", prefix, name)
}