daemon, plugin: follow containerd namespace conventions

Follow the conventions for namespace naming set out by other projects,
such as linuxkit and cri-containerd. Typically, they are some sort of
host name, with a subdomain describing functionality of the namespace.
In the case of linuxkit, services are launched in `services.linuxkit`.
In cri-containerd, pods are launched in `k8s.io`, making it clear that
these are from kubernetes.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

daemon/daemon.go

@@ -62,8 +62,8 @@ import (
 	"github.com/pkg/errors"
 )
 
-// MainNamespace is the name of the namespace used for users containers
-const MainNamespace = "moby"
+// ContainersNamespace is the name of the namespace used for users containers
+const ContainersNamespace = "moby"
 
 var (
 	errSystemNotSupported = errors.New("the Docker daemon is not supported on this platform")
@@ -890,7 +890,7 @@ func NewDaemon(config *config.Config, registryService registry.Service, containe
 
 	go d.execCommandGC()
 
-	d.containerd, err = containerdRemote.NewClient(MainNamespace, d)
+	d.containerd, err = containerdRemote.NewClient(ContainersNamespace, d)
 	if err != nil {
 		return nil, err
 	}

integration-cli/docker_cli_daemon_test.go

@@ -1451,7 +1451,7 @@ func (s *DockerDaemonSuite) TestCleanupMountsAfterDaemonAndContainerKill(c *chec
 
 	// kill the container
 	icmd.RunCommand(ctrBinary, "--address", "/var/run/docker/containerd/docker-containerd.sock",
-		"--namespace", moby_daemon.MainNamespace, "tasks", "kill", id).Assert(c, icmd.Success)
+		"--namespace", moby_daemon.ContainersNamespace, "tasks", "kill", id).Assert(c, icmd.Success)
 
 	// restart daemon.
 	d.Restart(c)
@@ -2011,7 +2011,7 @@ func (s *DockerDaemonSuite) TestDaemonRestartWithKilledRunningContainer(t *check
 
 	// kill the container
 	icmd.RunCommand(ctrBinary, "--address", "/var/run/docker/containerd/docker-containerd.sock",
-		"--namespace", moby_daemon.MainNamespace, "tasks", "kill", cid).Assert(t, icmd.Success)
+		"--namespace", moby_daemon.ContainersNamespace, "tasks", "kill", cid).Assert(t, icmd.Success)
 
 	// Give time to containerd to process the command if we don't
 	// the exit event might be received after we do the inspect
@@ -2106,7 +2106,7 @@ func (s *DockerDaemonSuite) TestDaemonRestartWithUnpausedRunningContainer(t *che
 	result := icmd.RunCommand(
 		ctrBinary,
 		"--address", "/var/run/docker/containerd/docker-containerd.sock",
-		"--namespace", moby_daemon.MainNamespace,
+		"--namespace", moby_daemon.ContainersNamespace,
 		"tasks", "resume", cid)
 	result.Assert(t, icmd.Success)
 

plugin/executor/containerd/containerd.go

@@ -16,7 +16,7 @@ import (
 )
 
 // PluginNamespace is the name used for the plugins namespace
-var PluginNamespace = "moby-plugins"
+var PluginNamespace = "plugins.moby"
 
 // ExitHandler represents an object that is called when the exit event is received from containerd
 type ExitHandler interface {