Merge pull request #4532 from cpuguy83/forward_signal_not_found

Fix some signal forwarder issues

cmd/ctr/commands/signals.go

@@ -23,6 +23,7 @@ import (
 	"syscall"
 
 	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/errdefs"
 	"github.com/sirupsen/logrus"
 )
 
@@ -36,8 +37,16 @@ func ForwardAllSignals(ctx gocontext.Context, task killer) chan os.Signal {
 	signal.Notify(sigc)
 	go func() {
 		for s := range sigc {
+			if canIgnoreSignal(s) {
+				logrus.Debugf("Ignoring signal %s", s)
+				continue
+			}
 			logrus.Debug("forwarding signal ", s)
 			if err := task.Kill(ctx, s.(syscall.Signal)); err != nil {
+				if errdefs.IsNotFound(err) {
+					logrus.WithError(err).Debugf("Not forwarding signal %s", s)
+					return
+				}
 				logrus.WithError(err).Errorf("forward signal %s", s)
 			}
 		}

cmd/ctr/commands/signals_linux.go

@@ -0,0 +1,27 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package commands
+
+import (
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+func canIgnoreSignal(s os.Signal) bool {
+	return s == unix.SIGURG
+}

cmd/ctr/commands/signals_notlinux.go

@@ -0,0 +1,25 @@
+//+build !linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package commands
+
+import "os"
+
+func canIgnoreSignal(_ os.Signal) bool {
+	return false
+}