@@ -422,6 +422,11 @@ func (container *Container) buildHostsFiles(IP string) error {

 		extraContent[alias] = child.NetworkSettings.IPAddress

 	}

+	for _, extraHost := range container.hostConfig.ExtraHosts {

+		parts := strings.Split(extraHost, ":")

+		extraContent[parts[0]] = parts[1]

+	}

+

 	return etchosts.Build(container.HostsPath, IP, container.Config.Hostname, container.Config.Domainname, &extraContent)

 }

@@ -7,6 +7,7 @@ docker-run - Run a command in a new container

 # SYNOPSIS

 **docker run**

 [**-a**|**--attach**[=*[]*]]

+[**--add-host**[=*[]*]]

 [**-c**|**--cpu-shares**[=*0*]]

 [**--cap-add**[=*[]*]]

 [**--cap-drop**[=*[]*]]

@@ -64,6 +65,10 @@ error. It can even pretend to be a TTY (this is what most commandline

 executables expect) and pass along signals. The **-a** option can be set for

 each of stdin, stdout, and stderr.

+**--add-host**=*hostname*:*ip*

+   Add a line to /etc/hosts. The format is hostname:ip.  The **--add-host**

+option can be set multiple times.

+

 **-c**, **--cpu-shares**=0

    CPU shares in relative weight. You can increase the priority of a container

 with the -c option. By default, all containers run at the same priority and get

@@ -986,6 +986,7 @@ removed before the image is removed.

     Run a command in a new container

       -a, --attach=[]            Attach to STDIN, STDOUT or STDERR.

+      --add-host=[]              Add a custom host-to-IP mapping (host:ip)

       -c, --cpu-shares=0         CPU shares (relative weight)

       --cap-add=[]               Add Linux capabilities

       --cap-drop=[]              Drop Linux capabilities

@@ -139,6 +139,7 @@ example, `docker run ubuntu:14.04`.

                                  'none': no networking for this container

                                  'container:<name|id>': reuses another container network stack

                                  'host': use the host network stack inside the container

+    --add-host=""   : Add a line to /etc/hosts (host:IP)

 By default, all containers have networking enabled and they can make any

 outgoing connections. The operator can completely disable networking

@@ -196,6 +197,22 @@ running the `redis-cli` command and connecting to the Redis server over the

     $ # use the redis container's network stack to access localhost

     $ sudo docker run --rm -ti --net container:redis example/redis-cli -h 127.0.0.1

+### Managing /etc/hosts

+

+Your container will have lines in `/etc/hosts` which define the hostname of the

+container itself as well as `localhost` and a few other common things.  The

+`--add-host` flag can be used to add additional lines to `/etc/hosts`.  

+

+    $ /docker run -ti --add-host db-static:86.75.30.9 ubuntu cat /etc/hosts

+    172.17.0.22     09d03f76bf2c

+    fe00::0         ip6-localnet

+    ff00::0         ip6-mcastprefix

+    ff02::1         ip6-allnodes

+    ff02::2         ip6-allrouters

+    127.0.0.1       localhost

+    ::1	            localhost ip6-localhost ip6-loopback

+    86.75.30.9      db-static

+

 ## Clean Up (–-rm)

 By default a container's file system persists even after the container

@@ -1331,6 +1331,23 @@ func TestDnsOptionsBasedOnHostResolvConf(t *testing.T) {

 	logDone("run - dns options based on host resolv.conf")

 }

+func TestRunAddHost(t *testing.T) {

+	defer deleteAllContainers()

+	cmd := exec.Command(dockerBinary, "run", "--add-host=extra:86.75.30.9", "busybox", "grep", "extra", "/etc/hosts")

+

+	out, _, err := runCommandWithOutput(cmd)

+	if err != nil {

+		t.Fatal(err, out)

+	}

+

+	actual := strings.Trim(out, "\r\n")

+	if actual != "86.75.30.9\textra" {

+		t.Fatalf("expected '86.75.30.9\textra', but says: '%s'", actual)

+	}

+

+	logDone("run - add-host option")

+}

+

 // Regression test for #6983

 func TestAttachStdErrOnlyTTYMode(t *testing.T) {

 	cmd := exec.Command(dockerBinary, "run", "-t", "-a", "stderr", "busybox", "true")

@@ -199,6 +199,17 @@ func validateDomain(val string) (string, error) {

 	return "", fmt.Errorf("%s is not a valid domain", val)

 }

+func ValidateExtraHost(val string) (string, error) {

+	arr := strings.Split(val, ":")

+	if len(arr) != 2 || len(arr[0]) == 0 {

+		return "", fmt.Errorf("bad format for add-host: %s", val)

+	}

+	if _, err := ValidateIPAddress(arr[1]); err != nil {

+		return "", fmt.Errorf("bad format for add-host: %s", val)

+	}

+	return val, nil

+}

+

 // Validates an HTTP(S) registry mirror

 func ValidateMirror(val string) (string, error) {

 	uri, err := url.Parse(val)

@@ -49,6 +49,7 @@ type HostConfig struct {

 	PublishAllPorts bool

 	Dns             []string

 	DnsSearch       []string

+	ExtraHosts      []string

 	VolumesFrom     []string

 	Devices         []DeviceMapping

 	NetworkMode     NetworkMode

@@ -81,6 +82,9 @@ func ContainerHostConfigFromJob(job *engine.Job) *HostConfig {

 	if DnsSearch := job.GetenvList("DnsSearch"); DnsSearch != nil {

 		hostConfig.DnsSearch = DnsSearch

 	}

+	if ExtraHosts := job.GetenvList("ExtraHosts"); ExtraHosts != nil {

+		hostConfig.ExtraHosts = ExtraHosts

+	}

 	if VolumesFrom := job.GetenvList("VolumesFrom"); VolumesFrom != nil {

 		hostConfig.VolumesFrom = VolumesFrom

 	}

@@ -54,6 +54,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf

 		flExpose      = opts.NewListOpts(nil)

 		flDns         = opts.NewListOpts(opts.ValidateIPAddress)

 		flDnsSearch   = opts.NewListOpts(opts.ValidateDnsSearch)

+		flExtraHosts  = opts.NewListOpts(opts.ValidateExtraHost)

 		flVolumesFrom = opts.NewListOpts(nil)

 		flLxcOpts     = opts.NewListOpts(nil)

 		flEnvFile     = opts.NewListOpts(nil)

@@ -93,6 +94,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf

 	cmd.Var(&flExpose, []string{"#expose", "-expose"}, "Expose a port from the container without publishing it to your host")

 	cmd.Var(&flDns, []string{"#dns", "-dns"}, "Set custom DNS servers")

 	cmd.Var(&flDnsSearch, []string{"-dns-search"}, "Set custom DNS search domains")

+	cmd.Var(&flExtraHosts, []string{"-add-host"}, "Add a custom host-to-IP mapping (host:ip)")

 	cmd.Var(&flVolumesFrom, []string{"#volumes-from", "-volumes-from"}, "Mount volumes from the specified container(s)")

 	cmd.Var(&flLxcOpts, []string{"#lxc-conf", "-lxc-conf"}, "(lxc exec-driver only) Add custom lxc options --lxc-conf=\"lxc.cgroup.cpuset.cpus = 0,1\"")

@@ -291,6 +293,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf

 		PublishAllPorts: *flPublishAll,

 		Dns:             flDns.GetAll(),

 		DnsSearch:       flDnsSearch.GetAll(),

+		ExtraHosts:      flExtraHosts.GetAll(),

 		VolumesFrom:     flVolumesFrom.GetAll(),

 		NetworkMode:     netMode,

 		Devices:         deviceMappings,