libct: remove dead network stats code

Network interface statistics were only collected for "veth" networks,
but the veth strategy was removed back in 2018 by commit fe3d5c4c
("Remove unused veth setup code"). Since then, a container with a veth
network can not even be started ("unknown strategy type"), so this code
is never reached, and the network interface stats are always empty.

Remove the dead code, and deprecate libcontainer.Stats.Interfaces and
types.Stats.NetworkInterfaces, which are always empty.

Network statistics are better obtained by whoever sets up the container
network (which runc does not do).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

events.go

@@ -178,7 +178,6 @@ func convertLibcontainerStats(ls *libcontainer.Stats) *types.Stats {
 		s.IntelRdt.Schemata = is.Schemata
 	}
 
-	s.NetworkInterfaces = ls.Interfaces
 	return &s
 }
 

libcontainer/container_linux.go

@@ -150,16 +150,6 @@ func (c *Container) Stats() (*Stats, error) {
 			return stats, fmt.Errorf("unable to get container Intel RDT stats: %w", err)
 		}
 	}
-	for _, iface := range c.config.Networks {
-		switch iface.Type {
-		case "veth":
-			istats, err := getNetworkInterfaceStats(iface.HostInterfaceName)
-			if err != nil {
-				return stats, fmt.Errorf("unable to get network stats for interface %q: %w", iface.HostInterfaceName, err)
-			}
-			stats.Interfaces = append(stats.Interfaces, istats)
-		}
-	}
 	return stats, nil
 }
 

libcontainer/network_linux.go

@@ -1,15 +1,10 @@
 package libcontainer
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
-	"os"
-	"path/filepath"
-	"strconv"
 
 	"github.com/opencontainers/runc/libcontainer/configs"
-	"github.com/opencontainers/runc/types"
 	"github.com/sirupsen/logrus"
 	"github.com/vishvananda/netlink"
 	"github.com/vishvananda/netlink/nl"
@@ -41,51 +36,6 @@ func getStrategy(tpe string) (networkStrategy, error) {
 	return s, nil
 }
 
-// Returns the network statistics for the network interfaces represented by the NetworkRuntimeInfo.
-func getNetworkInterfaceStats(interfaceName string) (*types.NetworkInterface, error) {
-	out := &types.NetworkInterface{Name: interfaceName}
-	// This can happen if the network runtime information is missing - possible if the
-	// container was created by an old version of libcontainer.
-	if interfaceName == "" {
-		return out, nil
-	}
-	type netStatsPair struct {
-		// Where to write the output.
-		Out *uint64
-		// The network stats file to read.
-		File string
-	}
-	// Ingress for host veth is from the container. Hence tx_bytes stat on the host veth is actually number of bytes received by the container.
-	netStats := []netStatsPair{
-		{Out: &out.RxBytes, File: "tx_bytes"},
-		{Out: &out.RxPackets, File: "tx_packets"},
-		{Out: &out.RxErrors, File: "tx_errors"},
-		{Out: &out.RxDropped, File: "tx_dropped"},
-
-		{Out: &out.TxBytes, File: "rx_bytes"},
-		{Out: &out.TxPackets, File: "rx_packets"},
-		{Out: &out.TxErrors, File: "rx_errors"},
-		{Out: &out.TxDropped, File: "rx_dropped"},
-	}
-	for _, netStat := range netStats {
-		data, err := readSysfsNetworkStats(interfaceName, netStat.File)
-		if err != nil {
-			return nil, err
-		}
-		*netStat.Out = data
-	}
-	return out, nil
-}
-
-// Reads the specified statistics available under /sys/class/net/<EthInterface>/statistics
-func readSysfsNetworkStats(ethInterface, statsFile string) (uint64, error) {
-	data, err := os.ReadFile(filepath.Join("/sys/class/net", ethInterface, "statistics", statsFile))
-	if err != nil {
-		return 0, err
-	}
-	return strconv.ParseUint(string(bytes.TrimSpace(data)), 10, 64)
-}
-
 // loopback is a network strategy that provides a basic loopback device
 type loopback struct{}
 

libcontainer/stats_linux.go

@@ -7,6 +7,8 @@ import (
 )
 
 type Stats struct {
+	// Deprecated: always empty. Network statistics should be obtained
+	// by whoever sets up the container network.
 	Interfaces    []*types.NetworkInterface
 	CgroupStats   *cgroups.Stats
 	IntelRdtStats *intelrdt.Stats

types/events.go

@@ -23,6 +23,7 @@ type Stats struct {
 	Blkio    Blkio              `json:"blkio"`
 	Hugetlb  map[string]Hugetlb `json:"hugetlb"`
 	IntelRdt IntelRdt           `json:"intel_rdt"`
+	// Deprecated: always empty.
 	NetworkInterfaces []*NetworkInterface `json:"network_interfaces"`
 }