fixup shim2

cmd/containerd-shim-runu-v2/service.go

@@ -22,11 +22,16 @@ package main
 import (
 	"context"
 	"os"
+	"syscall"
 
 	"github.com/containerd/containerd/errdefs"
+	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/runtime/v2/shim"
 	taskAPI "github.com/containerd/containerd/runtime/v2/task"
 	ptypes "github.com/gogo/protobuf/types"
+
+	"github.com/pkg/errors"
+	exec "golang.org/x/sys/execabs"
 )
 
 var (
@@ -43,8 +48,63 @@ type service struct {
 }
 
 // StartShim is a binary call that executes a new shim returning the address
-func (s *service) StartShim(ctx context.Context, opts shim.StartOpts) (string, error) {
-	return "", nil
+func (s *service) StartShim(ctx context.Context, opts shim.StartOpts) (_ string, retErr error) {
+	cmd, err := newCommand(ctx, opts.ID, opts.ContainerdBinary, opts.Address, opts.TTRPCAddress)
+	if err != nil {
+		return "", err
+	}
+	address, err := shim.SocketAddress(ctx, opts.Address, opts.ID)
+	if err != nil {
+		return "", err
+	}
+	socket, err := shim.NewSocket(address)
+	if err != nil {
+		if !shim.SocketEaddrinuse(err) {
+			return "", err
+		}
+		if err := shim.RemoveSocket(address); err != nil {
+			return "", errors.Wrap(err, "remove already used socket")
+		}
+		if socket, err = shim.NewSocket(address); err != nil {
+			return "", err
+		}
+	}
+	defer func() {
+		if retErr != nil {
+			socket.Close()
+			_ = shim.RemoveSocket(address)
+		}
+	}()
+	// make sure that reexec shim-v2 binary use the value if need
+	if err := shim.WriteAddress("address", address); err != nil {
+		return "", err
+	}
+
+	f, err := socket.File()
+	if err != nil {
+		return "", err
+	}
+
+	cmd.ExtraFiles = append(cmd.ExtraFiles, f)
+
+	if err := cmd.Start(); err != nil {
+		f.Close()
+		return "", err
+	}
+	defer func() {
+		if retErr != nil {
+			cmd.Process.Kill()
+		}
+	}()
+	// make sure to wait after start
+	go cmd.Wait()
+	if err := shim.WritePidFile("shim.pid", cmd.Process.Pid); err != nil {
+		return "", err
+	}
+	if err := shim.AdjustOOMScore(cmd.Process.Pid); err != nil {
+		return "", errors.Wrap(err, "failed to adjust OOM score for shim")
+	}
+	return address, nil
 }
 
 // Cleanup is a binary call that cleans up any resources used by the shim when the service crashes
@@ -137,3 +197,30 @@ func (s *service) Update(ctx context.Context, r *taskAPI.UpdateTaskRequest) (*pt
 func (s *service) Wait(ctx context.Context, r *taskAPI.WaitRequest) (*taskAPI.WaitResponse, error) {
 	return nil, errdefs.ErrNotImplemented
 }
+
+func newCommand(ctx context.Context, id, containerdBinary, containerdAddress, containerdTTRPCAddress string) (*exec.Cmd, error) {
+	ns, err := namespaces.NamespaceRequired(ctx)
+	if err != nil {
+		return nil, err
+	}
+	self, err := os.Executable()
+	if err != nil {
+		return nil, err
+	}
+	cwd, err := os.Getwd()
+	if err != nil {
+		return nil, err
+	}
+	args := []string{
+		"-namespace", ns,
+		"-id", id,
+		"-address", containerdAddress,
+	}
+	cmd := exec.Command(self, args...)
+	cmd.Dir = cwd
+	cmd.Env = append(os.Environ(), "GOMAXPROCS=4")
+	cmd.SysProcAttr = &syscall.SysProcAttr{
+		Setpgid: true,
+	}
+	return cmd, nil
+}