Allow stopping of paused container

When a container is paused, signals are sent once the container has been
unpaused.
Instead of forcing the user to unpause a container before they can ever
send a signal, allow the user to send the signals, and in the case of a
stop signal, automatically unpause the container afterwards.

This is much safer than unpausing the container first then sending a
signal (what a user is currently forced to do), as the container may be
paused for very good reasons and should not be unpaused except for
stopping.
Note that not even SIGKILL is possible while a process is paused,
but it is killed the instant it is unpaused.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Upstream-commit: c3feb046b9b1eb606cc7e853d020799eb3800e0e
Component: engine

components/engine/integration-cli/docker_cli_pause_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"strings"
+	"time"
 
 	"github.com/docker/docker/integration-cli/checker"
 	"github.com/docker/docker/integration-cli/cli"
@@ -65,3 +66,13 @@ func (s *DockerSuite) TestPauseFailsOnWindowsServerContainers(c *check.C) {
 	out, _, _ := dockerCmdWithError("pause", "test")
 	c.Assert(out, checker.Contains, "cannot pause Windows Server Containers")
 }
+
+func (s *DockerSuite) TestStopPausedContainer(c *check.C) {
+	testRequires(c, DaemonIsLinux)
+
+	id := runSleepingContainer(c)
+	cli.WaitRun(c, id)
+	cli.DockerCmd(c, "pause", id)
+	cli.DockerCmd(c, "stop", id)
+	cli.WaitForInspectResult(c, id, "{{.State.Running}}", "false", 30*time.Second)
+}

components/engine/integration-cli/docker_utils_test.go

@@ -396,7 +396,7 @@ func runSleepingContainerInImage(c *check.C, image string, extraArgs ...string)
 	args = append(args, extraArgs...)
 	args = append(args, image)
 	args = append(args, sleepCommandForDaemonPlatform()...)
-	return cli.DockerCmd(c, args...).Combined()
+	return strings.TrimSpace(cli.DockerCmd(c, args...).Combined())
 }
 
 // minimalBaseImage returns the name of the minimal base image for the current