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tracer_cgroup.go
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tracer_cgroup.go
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package main
import (
"fmt"
"io/fs"
"os"
"path"
"path/filepath"
"regexp"
"strconv"
"strings"
"github.com/kubeshark/tracer/pkg/discoverer"
"github.com/kubeshark/tracer/pkg/utils"
"github.com/rs/zerolog/log"
"k8s.io/apimachinery/pkg/types"
)
var numberRegex = regexp.MustCompile("[0-9]+")
type pidInformation struct {
podId types.UID
cgroupPath string
containerCgroupIds []uint64
}
type tracerCgroup struct {
pidsInfo map[uint32]pidInformation
}
func NewTracerCgroup(procfs string, containerIds map[string]types.UID) (*tracerCgroup, error) {
tc := &tracerCgroup{
pidsInfo: make(map[uint32]pidInformation),
}
isCgroupV2, err := utils.IsCgroupV2()
if err != nil {
return nil, err
}
pids, err := os.ReadDir(procfs)
if err != nil {
return nil, err
}
if isCgroupV2 {
if err = tc.scanPidsV2(procfs, pids, containerIds); err != nil {
return nil, err
}
} else {
if err = tc.scanPidsV1(procfs, pids, containerIds); err != nil {
return nil, err
}
}
return tc, nil
}
func (t *tracerCgroup) scanPidsV2(procfs string, pids []os.DirEntry, containerIds map[string]types.UID) error {
cgroupPaths := make(map[string][]uint32)
for _, pid := range pids {
if !numberRegex.MatchString(pid.Name()) {
continue
}
fpath := fmt.Sprintf("%s/%s/cgroup", procfs, pid.Name())
bytes, err := os.ReadFile(fpath)
if err != nil {
log.Debug().Err(err).Str("pid", pid.Name()).Msg("Couldn't read cgroup file.")
continue
}
n, err := strconv.ParseUint(pid.Name(), 10, 32)
if err != nil {
log.Warn().Err(err).Str("pid", pid.Name()).Msg("Couldn't parse pid number.")
continue
}
pInfo := t.pidsInfo[uint32(n)]
lines := strings.Split(string(bytes), "\n")
parts := strings.Split(lines[0], ":")
cgroupPath := parts[len(parts)-1]
parts = strings.Split(cgroupPath, "/")
parts = strings.Split(parts[len(parts)-1], "-")
parts = strings.Split(parts[len(parts)-1], ".")
containerId := parts[0]
// filter by ContainerID:
podUID, ok := containerIds[containerId]
if !ok {
continue
}
cgroupPaths[normalyzeCgroupV2Path(cgroupPath)] = append(cgroupPaths[normalyzeCgroupV2Path(cgroupPath)], uint32(n))
pInfo.podId = podUID
t.pidsInfo[uint32(n)] = pInfo
}
walk := func(s string, d fs.DirEntry, err error) error {
if err != nil {
return err
}
if d.IsDir() {
for cgroupPath := range cgroupPaths {
if !strings.HasSuffix(s, cgroupPath) {
continue
}
containerCgroupId, err := discoverer.GetCgroupIdByPath(s)
if err != nil {
log.Warn().Err(err).Str("path", s).Msg("Couldn't get container cgroup ID.")
continue
}
//TODO: removesyscallPoller.CgroupsInfo.Add(containerCgroupId, discoverer.GetContainerIdFromCgroupPath(cgroupPath))
for _, p := range cgroupPaths[cgroupPath] {
pInfo := t.pidsInfo[p]
pInfo.containerCgroupIds = append(pInfo.containerCgroupIds, containerCgroupId)
if pInfo.cgroupPath == "" {
pInfo.cgroupPath = filepath.Dir(s)
}
t.pidsInfo[p] = pInfo
}
}
return nil
}
return nil
}
lookupPaths := []string{
"/sys/fs/cgroup/kubepods.slice",
"/sys/fs/cgroup/system.slice",
"/sys/fs/cgroup",
}
for _, lookupPath := range lookupPaths {
_ = filepath.WalkDir(lookupPath, walk)
}
return nil
}
func (t *tracerCgroup) scanPidsV1(procfs string, pids []os.DirEntry, containerIds map[string]types.UID) error {
for _, pid := range pids {
if !numberRegex.MatchString(pid.Name()) {
continue
}
fpath := fmt.Sprintf("%s/%s/cgroup", procfs, pid.Name())
bytes, err := os.ReadFile(fpath)
if err != nil {
log.Debug().Err(err).Str("pid", pid.Name()).Msg("Couldn't read cgroup file.")
continue
}
n, err := strconv.ParseUint(pid.Name(), 10, 32)
if err != nil {
log.Warn().Err(err).Str("pid", pid.Name()).Msg("Couldn't parse pid number.")
continue
}
pInfo := t.pidsInfo[uint32(n)]
lines := strings.Split(string(bytes), "\n")
var cgroupPath string
if len(lines) == 1 {
parts := strings.Split(lines[0], ":")
cgroupPath = parts[len(parts)-1]
} else {
for _, line := range lines {
if strings.Contains(line, ":pids:") {
parts := strings.Split(line, ":")
cgroupPath = parts[len(parts)-1]
}
}
}
if cgroupPath == "" {
log.Error().Str("pid", pid.Name()).Msg(fmt.Sprintf("Cgroup path not found. Lines: %v", lines))
continue
}
cgroupPath = normalizeCgroup(cgroupPath)
podUID, ok := containerIds[cgroupPath]
if !ok {
continue
}
pInfo.podId = podUID
t.pidsInfo[uint32(n)] = pInfo
}
return nil
}
func normalyzeCgroupV2Path(path string) string {
normalizedPath := strings.ReplaceAll(path, "../", "")
if normalizedPath[0] == '/' {
normalizedPath = normalizedPath[1:]
}
return normalizedPath
}
// cgroup in the /proc/<pid>/cgroup may look something like
//
// /system.slice/docker-<ID>.scope
// /system.slice/containerd-<ID>.scope
// /kubepods.slice/kubepods-burstable.slice/kubepods-burstable-pod3beae8e0_164d_4689_a087_efd902d8c2ab.slice/docker-<ID>.scope
// /kubepods/besteffort/pod7709c1d5-447c-428f-bed9-8ddec35c93f4/<ID>
//
// This function extract the <ID> out of the cgroup path, the <ID> should match
//
// the "Container ID:" field when running kubectl describe pod <POD>
func normalizeCgroup(cgrouppath string) string {
basename := strings.TrimSpace(path.Base(cgrouppath))
if strings.Contains(basename, "-") {
basename = basename[strings.LastIndex(basename, "-")+1:]
}
if strings.Contains(basename, ".") {
return strings.TrimSuffix(basename, filepath.Ext(basename))
} else {
return basename
}
}