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Remove the ethtool kubelet dependency; use ip link instead of ethtool to determine pair interface. #30356

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Remove the ethtool kubelet dependency; use ip link instead of ethtool to determine pair interface. #30356

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20 changes: 7 additions & 13 deletions pkg/kubelet/network/hairpin/hairpin.go
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Original file line number Diff line number Diff line change
Expand Up @@ -36,10 +36,6 @@ const (
hairpinEnable = "1"
)

var (
ethtoolOutputRegex = regexp.MustCompile("peer_ifindex: (\\d+)")
)

func SetUpContainerPid(containerPid int, containerInterfaceName string) error {
pidStr := fmt.Sprintf("%d", containerPid)
nsenterArgs := []string{"-t", pidStr, "-n"}
Expand Down Expand Up @@ -69,24 +65,22 @@ func findPairInterfaceOfContainerInterface(e exec.Interface, containerInterfaceN
if err != nil {
return "", err
}
ethtoolPath, err := e.LookPath("ethtool")
if err != nil {
return "", err
}

nsenterArgs = append(nsenterArgs, "-F", "--", ethtoolPath, "--statistics", containerInterfaceName)
ipLinkOutputRegex := regexp.MustCompile(containerInterfaceName + "@if(\\d+)")

nsenterArgs = append(nsenterArgs, "-F", "--", "ip", "link", "show", containerInterfaceName)
output, err := e.Command(nsenterPath, nsenterArgs...).CombinedOutput()
if err != nil {
return "", fmt.Errorf("Unable to query interface %s of container %s: %v: %s", containerInterfaceName, containerDesc, err, string(output))
}
// look for peer_ifindex
match := ethtoolOutputRegex.FindSubmatch(output)
// look for the interface name which is named eth0@if{pair_interface}
match := ipLinkOutputRegex.FindSubmatch(output)
if match == nil {
return "", fmt.Errorf("No peer_ifindex in interface statistics for %s of container %s", containerInterfaceName, containerDesc)
return "", fmt.Errorf("No pair interface returned from container output %s. Description: %s", containerInterfaceName, containerDesc)
}
peerIfIndex, err := strconv.Atoi(string(match[1]))
if err != nil { // seems impossible (\d+ not numeric)
return "", fmt.Errorf("peer_ifindex wasn't numeric: %s: %v", match[1], err)
return "", fmt.Errorf("Pair interface wasn't numeric: %s: %v", match[1], err)
}
iface, err := net.InterfaceByIndex(peerIfIndex)
if err != nil {
Expand Down
5 changes: 3 additions & 2 deletions pkg/kubelet/network/hairpin/hairpin_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,8 +30,9 @@ import (
func TestFindPairInterfaceOfContainerInterface(t *testing.T) {
// there should be at least "lo" on any system
interfaces, _ := net.Interfaces()
validOutput := fmt.Sprintf("garbage\n peer_ifindex: %d", interfaces[0].Index)
invalidOutput := fmt.Sprintf("garbage\n unknown: %d", interfaces[0].Index)
// let's imagine eth0 in a container connects to iface index 1 on the host system (=localhost)
validOutput := fmt.Sprintf("2: eth0@if1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000")
invalidOutput := fmt.Sprintf("2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000")

tests := []struct {
output string
Expand Down