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containerd.go
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containerd.go
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package containerd
import (
"context"
"io"
"path/filepath"
"sync"
"github.com/containerd/containerd"
"github.com/containerd/containerd/linux/runcopts"
"github.com/docker/docker/api/errdefs"
"github.com/docker/docker/libcontainerd"
"github.com/opencontainers/runtime-spec/specs-go"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
)
// PluginNamespace is the name used for the plugins namespace
var PluginNamespace = "moby-plugins"
// ExitHandler represents an object that is called when the exit event is received from containerd
type ExitHandler interface {
HandleExitEvent(id string) error
}
// New creates a new containerd plugin executor
func New(rootDir string, remote libcontainerd.Remote, exitHandler ExitHandler) (*Executor, error) {
e := &Executor{
rootDir: rootDir,
exitHandler: exitHandler,
}
client, err := remote.NewClient(PluginNamespace, e)
if err != nil {
return nil, errors.Wrap(err, "error creating containerd exec client")
}
e.client = client
return e, nil
}
// Executor is the containerd client implementation of a plugin executor
type Executor struct {
rootDir string
client libcontainerd.Client
exitHandler ExitHandler
}
// Create creates a new container
func (e *Executor) Create(id string, spec specs.Spec, stdout, stderr io.WriteCloser) error {
opts := runcopts.RuncOptions{
RuntimeRoot: filepath.Join(e.rootDir, "runtime-root"),
}
ctx := context.Background()
err := e.client.Create(ctx, id, &spec, &opts)
if err != nil {
return err
}
_, err = e.client.Start(ctx, id, "", false, attachStreamsFunc(stdout, stderr))
return err
}
// Restore restores a container
func (e *Executor) Restore(id string, stdout, stderr io.WriteCloser) error {
alive, _, err := e.client.Restore(context.Background(), id, attachStreamsFunc(stdout, stderr))
if err != nil && !errdefs.IsNotFound(err) {
return err
}
if !alive {
_, _, err = e.client.DeleteTask(context.Background(), id)
if err != nil && !errdefs.IsNotFound(err) {
logrus.WithError(err).Errorf("failed to delete container plugin %s task from containerd", id)
return err
}
err = e.client.Delete(context.Background(), id)
if err != nil && !errdefs.IsNotFound(err) {
logrus.WithError(err).Errorf("failed to delete container plugin %s from containerd", id)
return err
}
}
return nil
}
// IsRunning returns if the container with the given id is running
func (e *Executor) IsRunning(id string) (bool, error) {
status, err := e.client.Status(context.Background(), id)
return status == libcontainerd.StatusRunning, err
}
// Signal sends the specified signal to the container
func (e *Executor) Signal(id string, signal int) error {
return e.client.SignalProcess(context.Background(), id, libcontainerd.InitProcessName, signal)
}
// ProcessEvent handles events from containerd
// All events are ignored except the exit event, which is sent of to the stored handler
func (e *Executor) ProcessEvent(id string, et libcontainerd.EventType, ei libcontainerd.EventInfo) error {
switch et {
case libcontainerd.EventExit:
// delete task and container
if _, _, err := e.client.DeleteTask(context.Background(), id); err != nil {
logrus.WithError(err).Errorf("failed to delete container plugin %s task from containerd", id)
}
if err := e.client.Delete(context.Background(), id); err != nil {
logrus.WithError(err).Errorf("failed to delete container plugin %s from containerd", id)
}
return e.exitHandler.HandleExitEvent(ei.ContainerID)
}
return nil
}
type cio struct {
containerd.IO
wg sync.WaitGroup
}
func (c *cio) Wait() {
c.wg.Wait()
c.IO.Wait()
}
func attachStreamsFunc(stdout, stderr io.WriteCloser) libcontainerd.StdioCallback {
return func(iop *libcontainerd.IOPipe) (containerd.IO, error) {
if iop.Stdin != nil {
iop.Stdin.Close()
// closing stdin shouldn't be needed here, it should never be open
panic("plugin stdin shouldn't have been created!")
}
cio := &cio{IO: iop}
cio.wg.Add(2)
go func() {
io.Copy(stdout, iop.Stdout)
stdout.Close()
cio.wg.Done()
}()
go func() {
io.Copy(stderr, iop.Stderr)
stderr.Close()
cio.wg.Done()
}()
return cio, nil
}
}