Merge pull request #583 from kzys/fix-tap-al2

Fix tap-related test failures

Author: kzys

.buildkite/al2_test.sh

@@ -18,6 +18,8 @@ sudo -E PATH=$PATH \
 containerd_pid=$!
 
 sudo $bin_path/firecracker-ctr --address $dir/containerd.sock content fetch docker.io/library/alpine:3.10.1
-sudo -E PATH=$bin_path:$PATH /usr/local/bin/go test -count=1 -run TestMultipleVMs_Isolated ./... -v
+
+TAP_PREFIX=build$BUILDKITE_BUILD_NUMBER \
+     sudo -E PATH=$bin_path:$PATH /usr/local/bin/go test -count=1 -run TestMultipleVMs_Isolated ./... -v
 
 sudo kill $containerd_pid

internal/vm/vsock.go

@@ -314,9 +314,9 @@ func (e vsockAckError) Temporary() bool {
 // error, according to the interface defined here:
 // https://golang.org/pkg/net/#Error
 func isTemporaryNetErr(err error) bool {
-	terr, ok := err.(interface {
+	type tempError interface {
 		Temporary() bool
-	})
-
-	return err != nil && ok && terr.Temporary()
+	}
+	var terr tempError
+	return err != nil && errors.As(err, &terr) && terr.Temporary()
 }

internal/vm/vsock_test.go

@@ -0,0 +1,27 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"). You may
+// not use this file except in compliance with the License. A copy of the
+// License is located at
+//
+//	http://aws.amazon.com/apache2.0/
+//
+// or in the "license" file accompanying this file. This file 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 vm
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTemporaryNetErr(t *testing.T) {
+	assert.False(t, isTemporaryNetErr(nil))
+	assert.False(t, isTemporaryNetErr(errors.New("hello")))
+	assert.True(t, isTemporaryNetErr(&vsockAckError{cause: errors.New("hello")}))
+}

runtime/service_integ_test.go

@@ -71,6 +71,8 @@ const (
 	numberOfVmsEnvName  = "NUMBER_OF_VMS"
 	defaultNumberOfVms  = 5
 
+	tapPrefixEnvName = "TAP_PREFIX"
+
 	defaultBalloonMemory         = int64(66)
 	defaultStatsPollingIntervals = int64(1)
 
@@ -223,30 +225,27 @@ func vmIDtoMacAddr(vmID uint) string {
 	return strings.Join(addrParts, ":")
 }
 
-func deleteTapDevice(ctx context.Context, tapName string) error {
-	if err := exec.CommandContext(ctx, "ip", "link", "delete", tapName).Run(); err != nil {
-		return err
+func ipCommand(ctx context.Context, args ...string) error {
+	out, err := exec.CommandContext(ctx, "ip", args...).CombinedOutput()
+	if err != nil {
+		s := strings.Trim(string(out), "\n")
+		return fmt.Errorf("failed to execute ip %s: %s: %w", strings.Join(args, " "), s, err)
 	}
+	return nil
+}
 
-	if err := exec.CommandContext(ctx, "ip", "tuntap", "del", tapName, "mode", "tap").Run(); err != nil {
+func deleteTapDevice(ctx context.Context, tapName string) error {
+	if err := ipCommand(ctx, "link", "delete", tapName); err != nil {
 		return err
 	}
-
-	return nil
+	return ipCommand(ctx, "tuntap", "del", tapName, "mode", "tap")
 }
 
 func createTapDevice(ctx context.Context, tapName string) error {
-	err := exec.CommandContext(ctx, "ip", "tuntap", "add", tapName, "mode", "tap").Run()
-	if err != nil {
-		return errors.Wrapf(err, "failed to create tap device %s", tapName)
-	}
-
-	err = exec.CommandContext(ctx, "ip", "link", "set", tapName, "up").Run()
-	if err != nil {
-		return errors.Wrapf(err, "failed to up tap device %s", tapName)
+	if err := ipCommand(ctx, "tuntap", "add", tapName, "mode", "tap"); err != nil {
+		return err
 	}
-
-	return nil
+	return ipCommand(ctx, "link", "set", tapName, "up")
 }
 
 func TestMultipleVMs_Isolated(t *testing.T) {
@@ -263,6 +262,8 @@ func TestMultipleVMs_Isolated(t *testing.T) {
 	}
 	t.Logf("TestMultipleVMs_Isolated: will run %d vm's", numberOfVms)
 
+	tapPrefix := os.Getenv(tapPrefixEnvName)
+
 	cases := []struct {
 		MaxContainers int32
 		JailerConfig  *proto.JailerConfig
@@ -319,7 +320,7 @@ func TestMultipleVMs_Isolated(t *testing.T) {
 			containerCount := c.MaxContainers
 			jailerConfig := c.JailerConfig
 
-			tapName := fmt.Sprintf("tap%d", vmID)
+			tapName := fmt.Sprintf("%stap%d", tapPrefix, vmID)
 			err := createTapDevice(ctx, tapName)
 			if err != nil {
 				return err