381 lines
8.8 KiB
Go
381 lines
8.8 KiB
Go
package shim
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import (
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"context"
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"encoding/json"
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"io/ioutil"
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"os"
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"os/exec"
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"path/filepath"
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"strconv"
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"sync"
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"syscall"
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"github.com/docker/containerd/execution"
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"github.com/docker/containerd/log"
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"github.com/pkg/errors"
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"github.com/sirupsen/logrus"
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"golang.org/x/sys/unix"
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runc "github.com/crosbymichael/go-runc"
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starttime "github.com/opencontainers/runc/libcontainer/system"
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)
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type newProcessOpts struct {
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shimBinary string
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runtime string
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runtimeArgs []string
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container *execution.Container
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exec bool
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execution.StartProcessOpts
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}
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func newProcess(ctx context.Context, o newProcessOpts) (*process, error) {
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procStateDir, err := o.container.StateDir().NewProcess(o.ID)
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if err != nil {
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return nil, err
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}
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exitPipe, controlPipe, err := getControlPipes(procStateDir)
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if err != nil {
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return nil, err
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}
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defer func() {
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if err != nil {
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exitPipe.Close()
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controlPipe.Close()
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}
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}()
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cmd, err := newShim(o, procStateDir)
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if err != nil {
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return nil, err
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}
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defer func() {
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if err != nil {
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cmd.Process.Kill()
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cmd.Wait()
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}
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}()
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abortCh := make(chan syscall.WaitStatus, 1)
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go func() {
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var shimStatus syscall.WaitStatus
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if err := cmd.Wait(); err != nil {
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shimStatus = execution.UnknownStatusCode
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} else {
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shimStatus = cmd.ProcessState.Sys().(syscall.WaitStatus)
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}
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abortCh <- shimStatus
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close(abortCh)
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}()
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process := &process{
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root: procStateDir,
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id: o.ID,
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exitChan: make(chan struct{}),
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exitPipe: exitPipe,
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controlPipe: controlPipe,
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}
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pid, stime, status, err := waitForPid(ctx, abortCh, procStateDir)
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if err != nil {
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return nil, err
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}
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process.pid = int64(pid)
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process.status = status
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process.startTime = stime
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return process, nil
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}
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func loadProcess(root, id string) (*process, error) {
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pid, err := runc.ReadPidFile(filepath.Join(root, pidFilename))
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if err != nil {
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return nil, err
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}
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stime, err := ioutil.ReadFile(filepath.Join(root, startTimeFilename))
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if err != nil {
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return nil, err
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}
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path := filepath.Join(root, exitPipeFilename)
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exitPipe, err := os.OpenFile(path, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
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if err != nil {
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return nil, err
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}
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defer func() {
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if err != nil {
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exitPipe.Close()
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}
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}()
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path = filepath.Join(root, controlPipeFilename)
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controlPipe, err := os.OpenFile(path, syscall.O_RDWR|syscall.O_NONBLOCK, 0)
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if err != nil {
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return nil, err
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}
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defer func() {
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if err != nil {
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controlPipe.Close()
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}
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}()
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p := &process{
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root: root,
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id: id,
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pid: int64(pid),
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exitChan: make(chan struct{}),
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exitPipe: exitPipe,
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controlPipe: controlPipe,
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startTime: string(stime),
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// TODO: status may need to be stored on disk to handle
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// Created state for init (i.e. a Start is needed to run the
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// container)
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status: execution.Running,
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}
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markAsStopped := func(p *process) (*process, error) {
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p.setStatus(execution.Stopped)
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return p, nil
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}
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if err = syscall.Kill(pid, 0); err != nil {
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if err == syscall.ESRCH {
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return markAsStopped(p)
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}
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return nil, err
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}
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cstime, err := starttime.GetProcessStartTime(pid)
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if err != nil {
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if os.IsNotExist(err) {
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return markAsStopped(p)
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}
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return nil, err
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}
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if p.startTime != cstime {
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return markAsStopped(p)
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}
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return p, nil
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}
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type process struct {
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root string
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id string
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pid int64
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exitChan chan struct{}
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exitPipe *os.File
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controlPipe *os.File
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startTime string
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status execution.Status
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ctx context.Context
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mu sync.Mutex
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}
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func (p *process) ID() string {
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return p.id
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}
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func (p *process) Pid() int64 {
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return p.pid
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}
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func (p *process) Wait() (uint32, error) {
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<-p.exitChan
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log.G(p.ctx).WithFields(logrus.Fields{"process-id": p.ID(), "pid": p.pid}).
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Debugf("wait is over")
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// Cleanup those fds
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p.exitPipe.Close()
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p.controlPipe.Close()
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// If the container process is still alive, it means the shim crashed
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// and the child process had updated it PDEATHSIG to something
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// else than SIGKILL. Or that epollCtl failed
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if p.isAlive() {
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err := syscall.Kill(int(p.pid), syscall.SIGKILL)
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if err != nil {
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return execution.UnknownStatusCode, errors.Wrap(err, "failed to kill process")
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}
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return uint32(128 + int(syscall.SIGKILL)), nil
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}
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data, err := ioutil.ReadFile(filepath.Join(p.root, exitStatusFilename))
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if err != nil {
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return execution.UnknownStatusCode, errors.Wrap(err, "failed to read process exit status")
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}
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if len(data) == 0 {
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return execution.UnknownStatusCode, errors.New(execution.ErrProcessNotExited.Error())
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}
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status, err := strconv.Atoi(string(data))
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if err != nil {
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return execution.UnknownStatusCode, errors.Wrapf(err, "failed to parse exit status")
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}
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p.setStatus(execution.Stopped)
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return uint32(status), nil
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}
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func (p *process) Signal(sig os.Signal) error {
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err := syscall.Kill(int(p.pid), sig.(syscall.Signal))
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if err != nil {
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return errors.Wrap(err, "failed to signal process")
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}
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return nil
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}
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func (p *process) Status() execution.Status {
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p.mu.Lock()
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s := p.status
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p.mu.Unlock()
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return s
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}
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func (p *process) setStatus(s execution.Status) {
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p.mu.Lock()
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p.status = s
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p.mu.Unlock()
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}
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func (p *process) isAlive() bool {
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if err := syscall.Kill(int(p.pid), 0); err != nil {
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if err == syscall.ESRCH {
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return false
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}
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log.G(p.ctx).WithFields(logrus.Fields{"process-id": p.ID(), "pid": p.pid}).
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Warnf("kill(0) failed: %v", err)
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return false
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}
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// check that we have the same startttime
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stime, err := starttime.GetProcessStartTime(int(p.pid))
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if err != nil {
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if os.IsNotExist(err) {
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return false
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}
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log.G(p.ctx).WithFields(logrus.Fields{"process-id": p.ID(), "pid": p.pid}).
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Warnf("failed to get process start time: %v", err)
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return false
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}
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if p.startTime != stime {
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return false
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}
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return true
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}
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func waitForPid(ctx context.Context, abortCh chan syscall.WaitStatus, root string) (pid int, stime string, status execution.Status, err error) {
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status = execution.Unknown
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for {
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select {
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case <-ctx.Done():
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return
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case wait := <-abortCh:
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if wait.Signaled() {
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err = errors.Errorf("shim died prematurarily: %v", wait.Signal())
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return
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}
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err = errors.Errorf("shim exited prematurarily with exit code %v", wait.ExitStatus())
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return
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default:
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}
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pid, err = runc.ReadPidFile(filepath.Join(root, pidFilename))
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if err == nil {
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break
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} else if !os.IsNotExist(err) {
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return
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}
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}
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status = execution.Created
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stime, err = starttime.GetProcessStartTime(pid)
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switch {
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case os.IsNotExist(err):
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status = execution.Stopped
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case err != nil:
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return
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default:
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var b []byte
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path := filepath.Join(root, startTimeFilename)
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b, err = ioutil.ReadFile(path)
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switch {
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case os.IsNotExist(err):
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err = ioutil.WriteFile(path, []byte(stime), 0600)
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if err != nil {
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return
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}
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case err != nil:
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err = errors.Wrapf(err, "failed to get start time for pid %d", pid)
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return
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case string(b) != stime:
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status = execution.Stopped
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}
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}
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return pid, stime, status, nil
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}
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func newShim(o newProcessOpts, workDir string) (*exec.Cmd, error) {
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cmd := exec.Command(o.shimBinary, o.container.ID(), o.container.Bundle(), o.runtime)
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cmd.Dir = workDir
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cmd.SysProcAttr = &syscall.SysProcAttr{
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Setpgid: true,
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}
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state := processState{
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Process: o.Spec,
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Exec: o.exec,
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Stdin: o.Stdin,
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Stdout: o.Stdout,
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Stderr: o.Stderr,
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RuntimeArgs: o.runtimeArgs,
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NoPivotRoot: false,
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CheckpointPath: "",
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RootUID: int(o.Spec.User.UID),
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RootGID: int(o.Spec.User.GID),
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}
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f, err := os.Create(filepath.Join(workDir, "process.json"))
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if err != nil {
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return nil, errors.Wrapf(err, "failed to create shim's process.json for container %s", o.container.ID())
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}
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defer f.Close()
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if err := json.NewEncoder(f).Encode(state); err != nil {
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return nil, errors.Wrapf(err, "failed to create shim's processState for container %s", o.container.ID())
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}
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if err := cmd.Start(); err != nil {
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return nil, errors.Wrapf(err, "failed to start shim for container %s", o.container.ID())
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}
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return cmd, nil
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}
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func getControlPipes(root string) (exitPipe *os.File, controlPipe *os.File, err error) {
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path := filepath.Join(root, exitPipeFilename)
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if err = unix.Mkfifo(path, 0700); err != nil {
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return exitPipe, controlPipe, errors.Wrap(err, "failed to create shim exit fifo")
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}
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if exitPipe, err = os.OpenFile(path, syscall.O_RDONLY|syscall.O_NONBLOCK, 0); err != nil {
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return exitPipe, controlPipe, errors.Wrap(err, "failed to open shim exit fifo")
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}
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path = filepath.Join(root, controlPipeFilename)
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if err = unix.Mkfifo(path, 0700); err != nil {
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return exitPipe, controlPipe, errors.Wrap(err, "failed to create shim control fifo")
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}
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if controlPipe, err = os.OpenFile(path, syscall.O_RDWR|syscall.O_NONBLOCK, 0); err != nil {
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return exitPipe, controlPipe, errors.Wrap(err, "failed to open shim control fifo")
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}
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return exitPipe, controlPipe, nil
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}
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