From ce93cb9d9c595dfc635f81b3f3ba3addfae3a17d Mon Sep 17 00:00:00 2001
From: Davanum Srinivas <davanum@gmail.com>
Date: Thu, 4 Aug 2016 12:58:04 -0400
Subject: [PATCH] Remove kubelet dependency on pkill

Issue #26093 identified pkill as one of the dependencies of kublet
which could be worked around.  Build on the code introduced for pidof
and regexp for the process(es) we need to send a signal to.

Related to #26093
---
 pkg/kubelet/cm/container_manager_linux.go |  2 +-
 pkg/kubelet/container_bridge.go           |  4 ++-
 pkg/util/procfs/procfs.go                 | 43 +++++++++++++++++++++--
 pkg/util/procfs/procfs_test.go            | 25 ++++++++++++-
 4 files changed, 69 insertions(+), 5 deletions(-)

diff --git a/pkg/kubelet/cm/container_manager_linux.go b/pkg/kubelet/cm/container_manager_linux.go
index 2230db98d6..dcbc72b3fc 100644
--- a/pkg/kubelet/cm/container_manager_linux.go
+++ b/pkg/kubelet/cm/container_manager_linux.go
@@ -525,7 +525,7 @@ func getPidsForProcess(name, pidFile string) ([]int, error) {
 			runtime.HandleError(err)
 		}
 	}
-	return procfs.PidOf(name), nil
+	return procfs.PidOf(name)
 }
 
 // Ensures that the Docker daemon is in the desired container.
diff --git a/pkg/kubelet/container_bridge.go b/pkg/kubelet/container_bridge.go
index 55a1f4827b..dc5259979c 100644
--- a/pkg/kubelet/container_bridge.go
+++ b/pkg/kubelet/container_bridge.go
@@ -27,6 +27,8 @@ import (
 	"github.com/golang/glog"
 	"k8s.io/kubernetes/pkg/util"
 	"k8s.io/kubernetes/pkg/util/iptables"
+	"k8s.io/kubernetes/pkg/util/procfs"
+	"syscall"
 )
 
 var cidrRegexp = regexp.MustCompile(`inet ([0-9a-fA-F.:]*/[0-9]*)`)
@@ -54,7 +56,7 @@ func createCBR0(wantCIDR *net.IPNet, babysitDaemons bool) error {
 	// For now just log the error. The containerRuntime check will catch docker failures.
 	// TODO (dawnchen) figure out what we should do for rkt here.
 	if babysitDaemons {
-		if err := exec.Command("pkill", "-KILL", "docker").Run(); err != nil {
+		if err := procfs.PKill("docker", syscall.SIGKILL); err != nil {
 			glog.Error(err)
 		}
 	} else if util.UsingSystemdInitSystem() {
diff --git a/pkg/util/procfs/procfs.go b/pkg/util/procfs/procfs.go
index 72d9abbe01..a7d95427e7 100644
--- a/pkg/util/procfs/procfs.go
+++ b/pkg/util/procfs/procfs.go
@@ -23,11 +23,14 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
+	"syscall"
 	"unicode"
 
 	"github.com/golang/glog"
+	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 )
 
 type ProcFS struct{}
@@ -62,7 +65,43 @@ func (pfs *ProcFS) GetFullContainerName(pid int) (string, error) {
 	return containerNameFromProcCgroup(string(content))
 }
 
-func PidOf(name string) []int {
+// Find process(es) using a regular expression and send a specified
+// signal to each process
+func PKill(name string, sig syscall.Signal) error {
+	if len(name) == 0 {
+		return fmt.Errorf("name should not be empty")
+	}
+	re, err := regexp.Compile(name)
+	if err != nil {
+		return err
+	}
+	pids := getPids(re)
+	if len(pids) == 0 {
+		return fmt.Errorf("unable to fetch pids for process name : %q", name)
+	}
+	errList := []error{}
+	for _, pid := range pids {
+		if err = syscall.Kill(pid, sig); err != nil {
+			errList = append(errList, err)
+		}
+	}
+	return utilerrors.NewAggregate(errList)
+}
+
+// Find process(es) with a specified name (exact match)
+// and return their pid(s)
+func PidOf(name string) ([]int, error) {
+	if len(name) == 0 {
+		return []int{}, fmt.Errorf("name should not be empty")
+	}
+	re, err := regexp.Compile("(^|/)" + name + "$")
+	if err != nil {
+		return []int{}, err
+	}
+	return getPids(re), nil
+}
+
+func getPids(re *regexp.Regexp) []int {
 	pids := []int{}
 	filepath.Walk("/proc", func(path string, info os.FileInfo, err error) error {
 		base := filepath.Base(path)
@@ -94,7 +133,7 @@ func PidOf(name string) []int {
 			return nil
 		}
 		// Check if the name of the executable is what we are looking for
-		if filepath.Base(exe[0]) == name {
+		if re.MatchString(exe[0]) {
 			dirname := filepath.Base(filepath.Dir(path))
 			// Grab the PID from the directory path
 			pid, _ := strconv.Atoi(dirname)
diff --git a/pkg/util/procfs/procfs_test.go b/pkg/util/procfs/procfs_test.go
index 848326217b..380b23e414 100644
--- a/pkg/util/procfs/procfs_test.go
+++ b/pkg/util/procfs/procfs_test.go
@@ -19,9 +19,12 @@ package procfs
 import (
 	"io/ioutil"
 	"os"
+	"os/signal"
 	"path/filepath"
 	"runtime"
+	"syscall"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
@@ -66,7 +69,27 @@ func TestPidOf(t *testing.T) {
 	if runtime.GOOS == "darwin" || runtime.GOOS == "windows" {
 		t.Skipf("not supported on GOOS=%s", runtime.GOOS)
 	}
-	pids := PidOf(filepath.Base(os.Args[0]))
+	pids, err := PidOf(filepath.Base(os.Args[0]))
+	assert.Empty(t, err)
 	assert.NotZero(t, pids)
 	assert.Contains(t, pids, os.Getpid())
 }
+
+func TestPKill(t *testing.T) {
+	if runtime.GOOS == "darwin" || runtime.GOOS == "windows" {
+		t.Skipf("not supported on GOOS=%s", runtime.GOOS)
+	}
+	sig := syscall.SIGCONT
+	c := make(chan os.Signal, 1)
+	signal.Notify(c, sig)
+	defer signal.Stop(c)
+	PKill(os.Args[0], sig)
+	select {
+	case s := <-c:
+		if s != sig {
+			t.Fatalf("signal was %v, want %v", s, sig)
+		}
+	case <-time.After(1 * time.Second):
+		t.Fatalf("timeout waiting for %v", sig)
+	}
+}