Add ctr shim command

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/ctr/shim.go

@@ -0,0 +1,124 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"os/exec"
+	"syscall"
+	"time"
+
+	gocontext "context"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/grpclog"
+
+	"github.com/docker/containerd/api/shim"
+	"github.com/urfave/cli"
+)
+
+var shimCommand = cli.Command{
+	Name:  "shim",
+	Usage: "interact with a shim directly",
+	Subcommands: []cli.Command{
+		shimCreateCommand,
+		shimStartCommand,
+		shimDeleteCommand,
+	},
+	Action: func(context *cli.Context) error {
+		cmd := exec.Command("containerd-shim", "--debug")
+		cmd.SysProcAttr = &syscall.SysProcAttr{}
+		cmd.SysProcAttr.Setpgid = true
+		if err := cmd.Start(); err != nil {
+			return err
+		}
+		fmt.Println("new shim started @ ./shim.sock")
+		return nil
+	},
+}
+
+var shimCreateCommand = cli.Command{
+	Name:  "create",
+	Usage: "create a container with a shim",
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "bundle",
+			Usage: "bundle path for the container",
+		},
+		cli.StringFlag{
+			Name:  "runtime",
+			Value: "runc",
+			Usage: "runtime to use for the container",
+		},
+	},
+	Action: func(context *cli.Context) error {
+		id := context.Args().First()
+		if id == "" {
+			return fmt.Errorf("container id must be provided")
+		}
+		service, err := getShimService()
+		if err != nil {
+			return err
+		}
+		r, err := service.Create(gocontext.Background(), &shim.CreateRequest{
+			ID:      id,
+			Bundle:  context.String("bundle"),
+			Runtime: context.String("runtime"),
+		})
+		if err != nil {
+			return err
+		}
+		fmt.Printf("container created with id %s and pid %d\n", id, r.Pid)
+		return nil
+	},
+}
+
+var shimStartCommand = cli.Command{
+	Name:  "start",
+	Usage: "start a container with a shim",
+	Action: func(context *cli.Context) error {
+		service, err := getShimService()
+		if err != nil {
+			return err
+		}
+		_, err = service.Start(gocontext.Background(), &shim.StartRequest{})
+		return err
+	},
+}
+
+var shimDeleteCommand = cli.Command{
+	Name:  "delete",
+	Usage: "delete a container with a shim",
+	Action: func(context *cli.Context) error {
+		service, err := getShimService()
+		if err != nil {
+			return err
+		}
+		r, err := service.Delete(gocontext.Background(), &shim.DeleteRequest{})
+		if err != nil {
+			return err
+		}
+		fmt.Printf("container deleted and returned exit status %d", r.ExitStatus)
+		return nil
+	},
+}
+
+func getShimService() (shim.ShimServiceClient, error) {
+	bindSocket := "shim.sock"
+
+	// 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", bindSocket, timeout)
+		},
+		))
+	conn, err := grpc.Dial(fmt.Sprintf("unix://%s", bindSocket), dialOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return shim.NewShimServiceClient(conn), nil
+
+}