fix: ctr run --cni get failed

when   user  executes ctr run --cni to start a container,it will call cni plugin to create network .But when user kills it,the network won’t be removed. if we run a container with same namespace and name again will trigger a bug. we should remove the network when user kills task if it enables cni plugin.

Fix:#6604

Signed-off-by: SongJiang Han <songjiang.dark@gmail.com>

cmd/ctr/commands/cni.go

@@ -0,0 +1,51 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package commands
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/namespaces"
+	"github.com/containerd/typeurl"
+)
+
+func init() {
+	typeurl.Register(&NetworkMetaData{},
+		"github.com/containerd/containerd/cmd/ctr/commands", "NetworkMetaData")
+}
+
+const (
+
+	// CtrCniMetadataExtension is an extension name that identify metadata of container in CreateContainerRequest
+	CtrCniMetadataExtension = "ctr.cni-containerd.metadata"
+)
+
+//ctr pass cni network metadata to containerd if ctr run use option of --cni
+type NetworkMetaData struct {
+	EnableCni bool
+}
+
+func FullID(ctx context.Context, c containerd.Container) string {
+	id := c.ID()
+	ns, ok := namespaces.Namespace(ctx)
+	if !ok {
+		return id
+	}
+	return fmt.Sprintf("%s-%s", ns, id)
+}