Remove cgo and use 'getent passwd' to lookup user names

.promu.yml

@@ -1,6 +1,6 @@
 go:
  version: 1.20
- cgo: true
+ cgo: false
 repository:
  path: github.com/treydock/cgroup_exporter
 build:

collector/cgroupv1.go

@@ -15,7 +15,6 @@ package collector
 
 import (
  "fmt"
- "os/user"
  "path/filepath"
  "regexp"
  "strings"
@@ -45,11 +44,11 @@ func getInfov1(name string, metric *CgroupMetric, logger log.Logger) {
  if len(userSliceMatch) == 2 {
  metric.userslice = true
  metric.uid = userSliceMatch[1]
- user, err := user.LookupId(metric.uid)
+ user, err := getentPasswd(metric.uid)
  if err != nil {
  level.Error(logger).Log("msg", "Error looking up user slice uid", "uid", metric.uid, "err", err)
  } else {
- metric.username = user.Username
+ metric.username = user
  }
  return
  }
@@ -59,11 +58,11 @@ func getInfov1(name string, metric *CgroupMetric, logger log.Logger) {
  metric.job = true
  metric.uid = slurmMatch[1]
  metric.jobid = slurmMatch[2]
- user, err := user.LookupId(metric.uid)
+ user, err := getentPasswd(metric.uid)
  if err != nil {
  level.Error(logger).Log("msg", "Error looking up slurm uid", "uid", metric.uid, "err", err)
  } else {
- metric.username = user.Username
+ metric.username = user
  }
  return
  }

collector/cgroupv2.go

@@ -88,12 +88,12 @@ func getInfov2(name string, pids []int, metric *CgroupMetric, logger log.Logger)
  // effective UID
  uid := procStat.UIDs[1]
  metric.uid = uid
- user, err := user.LookupId(metric.uid)
+ user, err := getentPasswd(metric.uid)
  if err != nil {
  level.Error(logger).Log("msg", "Error looking up slurm uid", "uid", metric.uid, "err", err)
  return
  }
- metric.username = user.Username
+ metric.username = user
  return
  }
 }

collector/collector.go

@@ -14,8 +14,11 @@
 package collector
 
 import (
+ "bytes"
+ "context"
  "fmt"
  "os"
+ "os/exec"
  "reflect"
  "strconv"
  "strings"
@@ -33,7 +36,9 @@ var (
  CgroupRoot = kingpin.Flag("path.cgroup.root", "Root path to cgroup fs").Default(defCgroupRoot).String()
  collectProcMaxExec = kingpin.Flag("collect.proc.max-exec", "Max length of process executable to record").Default("100").Int()
  ProcRoot = kingpin.Flag("path.proc.root", "Root path to proc fs").Default(defProcRoot).String()
+ userLookupTimeout = kingpin.Flag("exec.getent.timeout", "Timeout for running 'getent passwd' command").Default("5s").Duration()
  metricLock = sync.RWMutex{}
+ execCommand = exec.CommandContext
 )
 
 const (
@@ -311,3 +316,20 @@ func sliceContains(s interface{}, v interface{}) bool {
  }
  return false
 }
+
+func getentPasswd(uid string) (string, error) {
+ ctx, cancel := context.WithTimeout(context.Background(), *userLookupTimeout)
+ defer cancel()
+ cmd := execCommand(ctx, "getent", "passwd", uid)
+ var stdout, stderr bytes.Buffer
+ cmd.Stdout = &stdout
+ cmd.Stderr = &stderr
+ err := cmd.Run()
+ if ctx.Err() == context.DeadlineExceeded {
+ return "", fmt.Errorf("Timeout executing: getent passwd %s", uid)
+ } else if err != nil {
+ return "", fmt.Errorf("Error executing 'getent passwd %s': %s %s", uid, stderr.String(), err.Error())
+ }
+ username := strings.Split(stdout.String(), ":")[0]
+ return username, nil
+}

collector/collector_test.go

@@ -14,15 +14,25 @@
 package collector
 
 import (
+ "context"
  "os"
+ "os/exec"
  "path/filepath"
  "reflect"
  "runtime"
+ "strconv"
  "testing"
+ "time"
 
  "github.com/go-kit/log"
 )
 
+var (
+ mockedExitStatus = 0
+ mockedStdout string
+ _, cancel = context.WithTimeout(context.Background(), 5*time.Second)
+)
+
 func TestMain(m *testing.M) {
  _, filename, _, _ := runtime.Caller(0)
  dir := filepath.Dir(filename)
@@ -84,3 +94,33 @@ func TestGetProcInfo(t *testing.T) {
  }
  }
 }
+
+func fakeExecCommand(ctx context.Context, command string, args ...string) *exec.Cmd {
+ cs := []string{"-test.run=TestExecCommandHelper", "--", command}
+ cs = append(cs, args...)
+ defer cancel()
+ cmd := exec.CommandContext(ctx, os.Args[0], cs...)
+ es := strconv.Itoa(mockedExitStatus)
+ tmp, _ := os.MkdirTemp("", "fake")
+ cmd.Env = []string{"GO_WANT_HELPER_PROCESS=1",
+ "GOCOVERDIR=" + tmp,
+ "STDOUT=" + mockedStdout,
+ "EXIT_STATUS=" + es}
+ return cmd
+}
+
+func TestGetentPasswd(t *testing.T) {
+ timeout := 5 * time.Second
+ userLookupTimeout = &timeout
+ execCommand = fakeExecCommand
+ mockedExitStatus = 0
+ mockedStdout = "adm:x:3:4:adm:/var/adm:/sbin/nologin"
+ defer func() { execCommand = exec.CommandContext }()
+ user, err := getentPasswd("3")
+ if err != nil {
+ t.Errorf("Unexpected error: %s", err.Error())
+ }
+ if user != "adm" {
+ t.Errorf("Unexpected user: %s", user)
+ }
+}