containerd/linux/shim.go

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package linux
import (
"fmt"
"io/ioutil"
"log"
"net"
"os/exec"
"path/filepath"
"syscall"
"time"
"google.golang.org/grpc"
"google.golang.org/grpc/grpclog"
"github.com/docker/containerd/api/services/shim"
"github.com/docker/containerd/utils"
"github.com/pkg/errors"
)
func newShim(path string) (shim.ShimClient, error) {
socket := filepath.Join(path, "shim.sock")
l, err := utils.CreateUnixSocket(socket)
if err != nil {
return nil, err
}
cmd := exec.Command("containerd-shim")
cmd.Dir = path
f, err := l.(*net.UnixListener).File()
if err != nil {
return nil, err
}
cmd.ExtraFiles = append(cmd.ExtraFiles, f)
// make sure the shim can be re-parented to system init
// and is cloned in a new mount namespace because the overlay/filesystems
// will be mounted by the shim
cmd.SysProcAttr = &syscall.SysProcAttr{
Cloneflags: syscall.CLONE_NEWNS,
Setpgid: true,
}
if err := cmd.Start(); err != nil {
return nil, errors.Wrapf(err, "failed to start shim")
}
// close our side of the socket, do not close the listener as it will
// remove the socket from disk
f.Close()
// since we are currently the parent go ahead and make sure we wait on the shim
go cmd.Wait()
return connectShim(socket)
}
func loadShim(path string) (shim.ShimClient, error) {
socket := filepath.Join(path, "shim.sock")
return connectShim(socket)
// TODO: failed to connect to the shim, check if it's alive
// - if it is kill it
// - in both case call runc killall and runc delete on the id
}
func connectShim(socket string) (shim.ShimClient, error) {
// reset the logger for grpc to log to dev/null so that it does not mess with our stdio
grpclog.SetLogger(log.New(ioutil.Discard, "", log.LstdFlags))
dialOpts := []grpc.DialOption{grpc.WithInsecure(), grpc.WithTimeout(100 * time.Second)}
dialOpts = append(dialOpts,
grpc.WithDialer(func(addr string, timeout time.Duration) (net.Conn, error) {
return net.DialTimeout("unix", socket, timeout)
}),
grpc.WithBlock(),
grpc.WithTimeout(2*time.Second),
)
conn, err := grpc.Dial(fmt.Sprintf("unix://%s", socket), dialOpts...)
if err != nil {
return nil, errors.Wrapf(err, "failed to connect to shim via \"%s\"", fmt.Sprintf("unix://%s", socket))
}
return shim.NewShimClient(conn), nil
}