Fix exit event handling in shim

Could issues where when exec processes fail the wait block is not
released.

Second, you could not dump stacks if the reaper loop locks up.

Third, the publisher was not waiting on the correct pid.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/containerd-shim/main_unix.go

@@ -11,6 +11,7 @@ import (
 	"net"
 	"os"
 	"os/exec"
+	"os/signal"
 	"runtime"
 	"strings"
 	"sync"
@@ -80,6 +81,9 @@ func executeShim() error {
 	if err != nil {
 		return err
 	}
+	dump := make(chan os.Signal, 32)
+	signal.Notify(dump, syscall.SIGUSR1)
+
 	path, err := os.Getwd()
 	if err != nil {
 		return err
@@ -111,6 +115,11 @@ func executeShim() error {
 		"path":      path,
 		"namespace": namespaceFlag,
 	})
+	go func() {
+		for range dump {
+			dumpStacks(logger)
+		}
+	}()
 	return handleSignals(logger, signals, server, sv)
 }
 
@@ -171,8 +180,6 @@ func handleSignals(logger *logrus.Entry, signals chan os.Signal, server *ttrpc.S
 					sv.Delete(context.Background(), &ptypes.Empty{})
 					close(done)
 				})
-			case unix.SIGUSR1:
-				dumpStacks(logger)
 			}
 		}
 	}
@@ -213,8 +220,11 @@ func (l *remoteEventsPublisher) Publish(ctx context.Context, topic string, event
 	if err != nil {
 		return err
 	}
-	exit := <-c
+	status, err := reaper.Default.Wait(cmd, c)
-	if exit.Status != 0 {
+	if err != nil {
+		return err
+	}
+	if status != 0 {
 		return errors.New("failed to publish event")
 	}
 	return nil

cmd/containerd-shim/shim_linux.go

@@ -3,6 +3,7 @@ package main
 import (
 	"os"
 	"os/signal"
+	"syscall"
 
 	"github.com/containerd/containerd/reaper"
 	"github.com/containerd/containerd/sys"
@@ -14,7 +15,7 @@ import (
 // sub-reaper so that the container processes are reparented
 func setupSignals() (chan os.Signal, error) {
 	signals := make(chan os.Signal, 2048)
-	signal.Notify(signals)
+	signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT, syscall.SIGCHLD)
 	// make sure runc is setup to use the monitor
 	// for waiting on processes
 	runc.Monitor = reaper.Default

linux/proc/exec.go

@@ -143,6 +143,7 @@ func (e *execProcess) start(ctx context.Context) (err error) {
 		opts.ConsoleSocket = socket
 	}
 	if err := e.parent.runtime.Exec(ctx, e.parent.id, e.spec, opts); err != nil {
+		close(e.waitBlock)
 		return e.parent.runtimeError(err, "OCI runtime exec failed")
 	}
 	if e.stdio.Stdin != "" {

linux/shim/service.go

@@ -148,7 +148,6 @@ func (s *Service) Delete(ctx context.Context, r *ptypes.Empty) (*shimapi.DeleteR
 	if p == nil {
 		return nil, errdefs.ToGRPCf(errdefs.ErrFailedPrecondition, "container must be created")
 	}
-
 	if err := p.Delete(ctx); err != nil {
 		return nil, err
 	}
@@ -480,7 +479,7 @@ func (s *Service) getContainerPids(ctx context.Context, id string) ([]uint32, er
 func (s *Service) forward(publisher events.Publisher) {
 	for e := range s.events {
 		if err := publisher.Publish(s.context, getTopic(s.context, e), e); err != nil {
-			logrus.WithError(err).Error("post event")
+			log.G(s.context).WithError(err).Error("post event")
 		}
 	}
 }