@@ -44,15 +44,10 @@ type Container struct {

 // Sets PATH, HOSTNAME and if container.Config.Tty is set: TERM.

 // The defaults set here do not override the values in container.Config.Env

 func (container *Container) CreateDaemonEnvironment(linkedEnv []string) []string {

-	// if a domain name was specified, append it to the hostname (see #7851)

-	fullHostname := container.Config.Hostname

-	if container.Config.Domainname != "" {

-		fullHostname = fmt.Sprintf("%s.%s", fullHostname, container.Config.Domainname)

-	}

 	// Setup environment

 	env := []string{

 		"PATH=" + system.DefaultPathEnv,

-		"HOSTNAME=" + fullHostname,

+		"HOSTNAME=" + container.Config.Hostname,

 	}

 	if container.Config.Tty {

 		env = append(env, "TERM=xterm")

@@ -92,10 +87,6 @@ func (container *Container) BuildHostnameFile() error {

 		return err

 	}

 	container.HostnamePath = hostnamePath

-

-	if container.Config.Domainname != "" {

-		return ioutil.WriteFile(container.HostnamePath, []byte(fmt.Sprintf("%s.%s\n", container.Config.Hostname, container.Config.Domainname)), 0644)

-	}

 	return ioutil.WriteFile(container.HostnamePath, []byte(container.Config.Hostname+"\n"), 0644)

 }

@@ -671,13 +671,6 @@ func (daemon *Daemon) initializeNetworking(container *container.Container) error

 		if err != nil {

 			return err

 		}

-

-		parts := strings.SplitN(container.Config.Hostname, ".", 2)

-		if len(parts) > 1 {

-			container.Config.Hostname = parts[0]

-			container.Config.Domainname = parts[1]

-		}

-

 	}

 	if err := daemon.allocateNetwork(container); err != nil {

@@ -127,6 +127,7 @@ This section lists each version from latest to oldest.  Each listing includes a

 * `GET /containers/(id or name)/stats` now returns `pids_stats`, if the kernel is >= 4.3 and the pids cgroup is supported.

 * `POST /containers/create` now allows you to override usernamespaces remapping and use privileged options for the container.

 * `POST /auth` now returns an `IdentityToken` when supported by a registry.

+* `POST /containers/create` with both `Hostname` and `Domainname` fields specified will result in the container's hostname being set to `Hostname`, rather than `Hostname.Domainname`.

 ### v1.22 API changes

@@ -241,16 +241,6 @@ func Parse(cmd *flag.FlagSet, args []string) (*container.Config, *container.Host

 		entrypoint = strslice.StrSlice{*flEntrypoint}

 	}

-	var (

-		domainname string

-		hostname   = *flHostname

-		parts      = strings.SplitN(hostname, ".", 2)

-	)

-	if len(parts) > 1 {

-		hostname = parts[0]

-		domainname = parts[1]

-	}

-

 	ports, portBindings, err := nat.ParsePortSpecs(flPublish.GetAll())

 	if err != nil {

 		return nil, nil, nil, cmd, err

@@ -362,8 +352,7 @@ func Parse(cmd *flag.FlagSet, args []string) (*container.Config, *container.Host

 	}

 	config := &container.Config{

-		Hostname:     hostname,

-		Domainname:   domainname,

+		Hostname:     *flHostname,

 		ExposedPorts: ports,

 		User:         *flUser,

 		Tty:          *flTty,

@@ -391,11 +391,11 @@ func TestParseHostname(t *testing.T) {

 	if config, _ := mustParse(t, hostname); config.Hostname != "hostname" && config.Domainname != "" {

 		t.Fatalf("Expected the config to have 'hostname' as hostname, got '%v'", config.Hostname)

 	}

-	if config, _ := mustParse(t, hostnameWithDomain); config.Hostname != "hostname" && config.Domainname != "domainname" {

-		t.Fatalf("Expected the config to have 'hostname' as hostname, got '%v'", config.Hostname)

+	if config, _ := mustParse(t, hostnameWithDomain); config.Hostname != "hostname.domainname" && config.Domainname != "" {

+		t.Fatalf("Expected the config to have 'hostname' as hostname.domainname, got '%v'", config.Hostname)

 	}

-	if config, _ := mustParse(t, hostnameWithDomainTld); config.Hostname != "hostname" && config.Domainname != "domainname.tld" {

-		t.Fatalf("Expected the config to have 'hostname' as hostname, got '%v'", config.Hostname)

+	if config, _ := mustParse(t, hostnameWithDomainTld); config.Hostname != "hostname.domainname.tld" && config.Domainname != "" {

+		t.Fatalf("Expected the config to have 'hostname' as hostname.domainname.tld, got '%v'", config.Hostname)

 	}

 }