When container stops, drop sig-proxy errors to infos

The sig-proxy code is set up to error on failing to forward
signals to a container. This is reasonable in cases where the
container is running, but something strange went wrong - but when
the Kill fails because the container is stopped, we shouldn't
bother with aggressive Error logging since this is an expected
part of the container lifecycle - it stops, and then `podman run`
also stops, but there is a timing window in between where signals
will fail to be proxied, and we should not print angry errors
during that.

Signed-off-by: Matthew Heon <[email protected]>

pkg/domain/infra/abi/terminal/sigproxy_linux.go

@@ -5,8 +5,10 @@ import (
 	"syscall"
 
 	"github.com/containers/podman/v2/libpod"
+	"github.com/containers/podman/v2/libpod/define"
 	"github.com/containers/podman/v2/libpod/shutdown"
 	"github.com/containers/podman/v2/pkg/signal"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -33,12 +35,16 @@ func ProxySignals(ctr *libpod.Container) {
 			}
 
 			if err := ctr.Kill(uint(s.(syscall.Signal))); err != nil {
+				if errors.Cause(err) == define.ErrCtrStateInvalid {
+					logrus.Infof("Ceasing signal forwarding to container %s as it has stopped", ctr.ID())
+				} else {
+					logrus.Errorf("Error forwarding signal %d to container %s: %v", s, ctr.ID(), err)
+				}
 				// If the container dies, and we find out here,
 				// we need to forward that one signal to
 				// ourselves so that it is not lost, and then
 				// we terminate the proxy and let the defaults
 				// play out.
-				logrus.Errorf("Error forwarding signal %d to container %s: %v", s, ctr.ID(), err)
 				signal.StopCatch(sigBuffer)
 				if err := syscall.Kill(syscall.Getpid(), s.(syscall.Signal)); err != nil {
 					logrus.Errorf("failed to kill pid %d", syscall.Getpid())