@@ -12,6 +12,7 @@ import (

 	"github.com/docker/docker/container"

 	"github.com/docker/docker/daemon/network"

 	derr "github.com/docker/docker/errors"

+	"github.com/docker/docker/pkg/stringid"

 	"github.com/docker/docker/runconfig"

 	containertypes "github.com/docker/engine-api/types/container"

 	networktypes "github.com/docker/engine-api/types/network"

@@ -485,6 +486,18 @@ func (daemon *Daemon) updateNetworkConfig(container *container.Container, idOrNa

 		if endpointConfig != nil && len(endpointConfig.Aliases) > 0 {

 			return nil, runconfig.ErrUnsupportedNetworkAndAlias

 		}

+	} else {

+		addShortID := true

+		shortID := stringid.TruncateID(container.ID)

+		for _, alias := range endpointConfig.Aliases {

+			if alias == shortID {

+				addShortID = false

+				break

+			}

+		}

+		if addShortID {

+			endpointConfig.Aliases = append(endpointConfig.Aliases, shortID)

+		}

 	}

 	n, err := daemon.FindNetwork(idOrName)

@@ -505,6 +518,9 @@ func (daemon *Daemon) updateNetworkConfig(container *container.Container, idOrNa

 }

 func (daemon *Daemon) connectToNetwork(container *container.Container, idOrName string, endpointConfig *networktypes.EndpointSettings, updateSettings bool) (err error) {

+	if endpointConfig == nil {

+		endpointConfig = &networktypes.EndpointSettings{}

+	}

 	n, err := daemon.updateNetworkConfig(container, idOrName, endpointConfig, updateSettings)

 	if err != nil {

 		return err

@@ -533,10 +549,7 @@ func (daemon *Daemon) connectToNetwork(container *container.Container, idOrName

 			}

 		}

 	}()

-

-	if endpointConfig != nil {

-		container.NetworkSettings.Networks[n.Name()] = endpointConfig

-	}

+	container.NetworkSettings.Networks[n.Name()] = endpointConfig

 	if err := daemon.updateEndpointNetworkSettings(container, n, ep); err != nil {

 		return err

@@ -101,6 +101,9 @@ func (daemon *Daemon) getSize(container *container.Container) (int64, int64) {

 // ConnectToNetwork connects a container to a network

 func (daemon *Daemon) ConnectToNetwork(container *container.Container, idOrName string, endpointConfig *networktypes.EndpointSettings) error {

+	if endpointConfig == nil {

+		endpointConfig = &networktypes.EndpointSettings{}

+	}

 	if !container.Running {

 		if container.RemovalInProgress || container.Dead {

 			return errRemovalContainer(container.ID)

@@ -108,9 +111,7 @@ func (daemon *Daemon) ConnectToNetwork(container *container.Container, idOrName

 		if _, err := daemon.updateNetworkConfig(container, idOrName, endpointConfig, true); err != nil {

 			return err

 		}

-		if endpointConfig != nil {

-			container.NetworkSettings.Networks[idOrName] = endpointConfig

-		}

+		container.NetworkSettings.Networks[idOrName] = endpointConfig

 	} else {

 		if err := daemon.connectToNetwork(container, idOrName, endpointConfig, true); err != nil {

 			return err

@@ -14,6 +14,7 @@ import (

 	"time"

 	"github.com/docker/docker/pkg/integration/checker"

+	"github.com/docker/docker/pkg/stringid"

 	"github.com/docker/docker/runconfig"

 	"github.com/docker/engine-api/types"

 	"github.com/docker/engine-api/types/versions/v1p20"

@@ -1348,7 +1349,7 @@ func (s *DockerSuite) TestUserDefinedNetworkConnectDisconnectAlias(c *check.C) {

 	dockerCmd(c, "network", "create", "-d", "bridge", "net1")

 	dockerCmd(c, "network", "create", "-d", "bridge", "net2")

-	dockerCmd(c, "run", "-d", "--net=net1", "--name=first", "--net-alias=foo", "busybox", "top")

+	cid, _ := dockerCmd(c, "run", "-d", "--net=net1", "--name=first", "--net-alias=foo", "busybox", "top")

 	c.Assert(waitRun("first"), check.IsNil)

 	dockerCmd(c, "run", "-d", "--net=net1", "--name=second", "busybox", "top")

@@ -1360,6 +1361,10 @@ func (s *DockerSuite) TestUserDefinedNetworkConnectDisconnectAlias(c *check.C) {

 	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", "foo")

 	c.Assert(err, check.IsNil)

+	// ping first container's short-id alias

+	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", stringid.TruncateID(cid))

+	c.Assert(err, check.IsNil)

+

 	// connect first container to net2 network

 	dockerCmd(c, "network", "connect", "--alias=bar", "net2", "first")

 	// connect second container to foo2 network with a different alias for first container

@@ -1379,6 +1384,9 @@ func (s *DockerSuite) TestUserDefinedNetworkConnectDisconnectAlias(c *check.C) {

 	// ping to net2 scoped alias "bar" must still succeed

 	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", "bar")

 	c.Assert(err, check.IsNil)

+	// ping to net2 scoped alias short-id must still succeed

+	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", stringid.TruncateID(cid))

+	c.Assert(err, check.IsNil)

 	// verify the alias option is rejected when running on predefined network

 	out, _, err := dockerCmdWithError("run", "--rm", "--name=any", "--net-alias=any", "busybox", "top")

@@ -20,6 +20,7 @@ import (

 	"github.com/docker/docker/pkg/integration/checker"

 	"github.com/docker/docker/pkg/mount"

+	"github.com/docker/docker/pkg/stringid"

 	"github.com/docker/docker/pkg/stringutils"

 	"github.com/docker/docker/runconfig"

 	"github.com/docker/go-connections/nat"

@@ -285,12 +286,22 @@ func (s *DockerSuite) TestUserDefinedNetworkAlias(c *check.C) {

 	testRequires(c, DaemonIsLinux, NotUserNamespace, NotArm)

 	dockerCmd(c, "network", "create", "-d", "bridge", "net1")

-	dockerCmd(c, "run", "-d", "--net=net1", "--name=first", "--net-alias=foo1", "--net-alias=foo2", "busybox", "top")

+	cid1, _ := dockerCmd(c, "run", "-d", "--net=net1", "--name=first", "--net-alias=foo1", "--net-alias=foo2", "busybox", "top")

 	c.Assert(waitRun("first"), check.IsNil)

-	dockerCmd(c, "run", "-d", "--net=net1", "--name=second", "busybox", "top")

+	// Check if default short-id alias is added automatically

+	id := strings.TrimSpace(cid1)

+	aliases := inspectField(c, id, "NetworkSettings.Networks.net1.Aliases")

+	c.Assert(aliases, checker.Contains, stringid.TruncateID(id))

+

+	cid2, _ := dockerCmd(c, "run", "-d", "--net=net1", "--name=second", "busybox", "top")

 	c.Assert(waitRun("second"), check.IsNil)

+	// Check if default short-id alias is added automatically

+	id = strings.TrimSpace(cid2)

+	aliases = inspectField(c, id, "NetworkSettings.Networks.net1.Aliases")

+	c.Assert(aliases, checker.Contains, stringid.TruncateID(id))

+

 	// ping to first and its network-scoped aliases

 	_, _, err := dockerCmdWithError("exec", "second", "ping", "-c", "1", "first")

 	c.Assert(err, check.IsNil)

@@ -298,6 +309,9 @@ func (s *DockerSuite) TestUserDefinedNetworkAlias(c *check.C) {

 	c.Assert(err, check.IsNil)

 	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", "foo2")

 	c.Assert(err, check.IsNil)

+	// ping first container's short-id alias

+	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", stringid.TruncateID(cid1))

+	c.Assert(err, check.IsNil)

 	// Restart first container

 	dockerCmd(c, "restart", "first")

@@ -310,6 +324,9 @@ func (s *DockerSuite) TestUserDefinedNetworkAlias(c *check.C) {

 	c.Assert(err, check.IsNil)

 	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", "foo2")

 	c.Assert(err, check.IsNil)

+	// ping first container's short-id alias

+	_, _, err = dockerCmdWithError("exec", "second", "ping", "-c", "1", stringid.TruncateID(cid1))

+	c.Assert(err, check.IsNil)

 }

 // Issue 9677.