Add container's short-id as default network alias

link feature in docker0 bridge by default provides short-id as a
container alias. With built-in SD feature, providing a container
short-id as a network alias will fill that gap.

Signed-off-by: Madhu Venugopal <madhu@docker.com>

daemon/container_operations.go

@@ -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

daemon/container_operations_unix.go

@@ -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

integration-cli/docker_cli_network_unix_test.go

@@ -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")

integration-cli/docker_cli_run_test.go

@@ -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.