agent: Reap child processes during the pod lifecycle

All processes started by libcontainer leave a defunct process behind.
This process is a child from our agent and has to be reaped before we
wait for the end of every process.

Fixes #71

Signed-off-by: Sebastien Boeuf <[email protected]>

agent.go

@@ -687,6 +687,11 @@ func (p *pod) runContainerProcess(cid, pid string, terminal bool, started chan e
 		}
 	}
 
+	if err := reapChildProcesses(); err != nil {
+		agentLog.Errorf("Could not reap the child: %v", err)
+		return err
+	}
+
 	started <- nil
 
 	processState, err := p.containers[cid].processes[pid].process.Wait()
@@ -706,6 +711,7 @@ func (p *pod) runContainerProcess(cid, pid string, terminal bool, started chan e
 	// Get exit code
 	exitCode := uint8(255)
 	if processState != nil {
+		agentLog.Infof("ProcessState: %+v", processState)
 		if waitStatus, ok := processState.Sys().(syscall.WaitStatus); ok {
 			exitCode = uint8(waitStatus.ExitStatus())
 		}
@@ -717,6 +723,20 @@ func (p *pod) runContainerProcess(cid, pid string, terminal bool, started chan e
 	return nil
 }
 
+func reapChildProcesses() error {
+	var ws unix.WaitStatus
+	var rus unix.Rusage
+
+	pid, err := unix.Wait4(0, &ws, 0, &rus)
+	if err != nil {
+		return err
+	}
+
+	agentLog.Infof("Process %d reaped", pid)
+
+	return nil
+}
+
 func (p *pod) buildProcessWithoutTerminal(proc *process) (*process, error) {
 	rStdin, wStdin, err := os.Pipe()
 	if err != nil {