only delete network which created by kind.

Signed-off-by: Jintao Zhang <zhangjintao9020@gmail.com>

Author: tao12345666333

pkg/container/docker/network.go

@@ -18,6 +18,7 @@ package docker
 
 import (
 	"fmt"
+	"strings"
 
 	"sigs.k8s.io/kind/pkg/cluster/constants"
 	"sigs.k8s.io/kind/pkg/exec"
@@ -36,13 +37,17 @@ func CreateNetwork(networkName string) error {
 }
 
 // DeleteNetwork delete the special network
+// only when the network was created by kind
 func DeleteNetwork(networkName string) error {
-	cmd := exec.Command(
-		"docker", "network",
-		"rm",
-		networkName,
-	)
-	return cmd.Run()
+	if isNetworkCreatedByKind(networkName) {
+		cmd := exec.Command(
+			"docker", "network",
+			"rm",
+			networkName,
+		)
+		return cmd.Run()
+	}
+	return nil
 }
 
 // IsNetworkExist check if the network exist
@@ -58,3 +63,26 @@ func IsNetworkExist(networkName string) bool {
 
 	return true
 }
+
+// isNetworkCreatedByKind checks if it was created by kind
+func isNetworkCreatedByKind(networkName string) bool {
+	cmd := exec.Command(
+		"docker", "network",
+		"ls",
+		"--filter=label="+fmt.Sprintf("%s=%s", constants.ClusterLabelKey, networkName),
+		"--format='{{ .Name }}'",
+	)
+
+	lines, err := exec.CombinedOutputLines(cmd)
+
+	if err != nil {
+		return false
+	}
+
+	ok := strings.Contains(strings.Join(lines, ","), networkName)
+
+	if ok {
+		return true
+	}
+	return false
+}

pkg/container/docker/network_test.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2019 The Kubernetes 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 docker
+
+import "testing"
+
+func TestNetworkAction(t *testing.T) {
+	var testNetworkName = "kind-test-network"
+
+	if err := CreateNetwork(testNetworkName); err != nil {
+		t.Error("expected an error for CreateNetwork")
+	}
+
+	if willBeTrue := IsNetworkExist(testNetworkName); willBeTrue != true {
+		t.Error("expected an error for IsNetworkExist")
+	}
+
+	if willBeTrue := isNetworkCreatedByKind(testNetworkName); willBeTrue != true {
+		t.Error("expected an error for isNetworkCreatedByKind")
+	}
+
+	if err := DeleteNetwork(testNetworkName); err != nil {
+		t.Error("expected an error for DeleteNetwork")
+	}
+
+	if willBeFalse := isNetworkCreatedByKind(testNetworkName); willBeFalse != false {
+		t.Error("expected an error for isNetworkCreatedByKind")
+	}
+
+	if willBeFalse := isNetworkCreatedByKind("qwerty.asdfg"); willBeFalse != false {
+		t.Error("expected an error for isNetworkCreatedByKind")
+	}
+
+}