container: add exec command prototype

Signed-off-by: Jacek J. Łakis <jacek.lakis@intel.com>

server/container_exec.go

@@ -1,11 +1,38 @@
 package server
 
 import (
+	"fmt"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/kubernetes-incubator/cri-o/oci"
 	"golang.org/x/net/context"
 	pb "k8s.io/kubernetes/pkg/kubelet/api/v1alpha1/runtime"
 )
 
 // Exec prepares a streaming endpoint to execute a command in the container.
 func (s *Server) Exec(ctx context.Context, req *pb.ExecRequest) (*pb.ExecResponse, error) {
-	return &pb.ExecResponse{}, nil
+	logrus.Debugf("ExecRequest %+v", req)
+	c, err := s.getContainerFromRequest(req.ContainerId)
+	if err != nil {
+		return nil, err
+	}
+
+	if err = s.runtime.UpdateStatus(c); err != nil {
+		return nil, err
+	}
+
+	cState := s.runtime.ContainerStatus(c)
+	if !(cState.Status == oci.ContainerStateRunning || cState.Status == oci.ContainerStateCreated) {
+		return nil, fmt.Errorf("container is not created or running")
+	}
+
+	if req.Cmd == nil {
+		return nil, fmt.Errorf("exec command cannot be empty")
+	}
+
+	url := "url"
+
+	return &pb.ExecResponse{
+		Url: url,
+	}, nil
 }