Fix errors when trying to kill whole process group.

client/driver/executor/executor.go

@@ -437,6 +437,10 @@ var (
 	// finishedErr is the error message received when trying to kill and already
 	// exited process.
 	finishedErr = "os: process already finished"
+
+	// noSuchProcessErr is the error message received when trying to kill a non
+	// existing process (e.g. when killing a process group).
+	noSuchProcessErr = "no such process"
 )
 
 // ClientCleanup is the cleanup routine that a Nomad Client uses to remove the
@@ -450,7 +454,10 @@ func (e *UniversalExecutor) cleanupUserLeftovers(proc *os.Process) error {
 	// If new process group was created upon command execution
 	// we can kill the whole process group now to cleanup any leftovers.
 	if e.cmd.SysProcAttr != nil && e.cmd.SysProcAttr.Setpgid {
-		return syscall.Kill(-proc.Pid, syscall.SIGKILL)
+		if err := syscall.Kill(-proc.Pid, syscall.SIGKILL); err != nil && err.Error() != noSuchProcessErr {
+			return err
+		}
+		return nil
 	} else {
 		return proc.Kill()
 	}

client/driver/executor/executor_basic.go

@@ -29,10 +29,6 @@ func (e *UniversalExecutor) configureIsolation() error {
 	return nil
 }
 
-func (e *UniversalExecutor) setNewProcessGroup() error {
-	return nil
-}
-
 func (e *UniversalExecutor) Stats() (*cstructs.TaskResourceUsage, error) {
 	pidStats, err := e.pidStats()
 	if err != nil {

client/driver/executor/executor_unix.go

@@ -5,6 +5,7 @@ package executor
 import (
 	"fmt"
 	"io"
+	"runtime"
 	"syscall"
 
 	syslog "github.com/RackSec/srslog"
@@ -51,6 +52,10 @@ func (e *UniversalExecutor) collectLogs(we io.Writer, wo io.Writer) {
 
 // configure new process group for child process
 func (e *UniversalExecutor) setNewProcessGroup() error {
+	// We need to check that as build flags includes windows for this file
+	if runtime.GOOS == "windows" {
+		return nil
+	}
 	if e.cmd.SysProcAttr == nil {
 		e.cmd.SysProcAttr = &syscall.SysProcAttr{}
 	}