Merge pull request #7677 from erikh/update_hosts_linked_containers

Update /etc/hosts when linked container is restarted

daemon/container.go

@@ -297,6 +297,9 @@ func (container *Container) Start() (err error) {
 	if err := container.initializeNetworking(); err != nil {
 		return err
 	}
+	if err := container.updateParentsHosts(); err != nil {
+		return err
+	}
 	container.verifyDaemonSettings()
 	if err := prepareVolumesForContainer(container); err != nil {
 		return err
@@ -390,10 +393,7 @@ func (container *Container) buildHostnameFile() error {
 	return ioutil.WriteFile(container.HostnamePath, []byte(container.Config.Hostname+"\n"), 0644)
 }
 
-func (container *Container) buildHostnameAndHostsFiles(IP string) error {
-	if err := container.buildHostnameFile(); err != nil {
-		return err
-	}
+func (container *Container) buildHostsFiles(IP string) error {
 
 	hostsPath, err := container.getRootResourcePath("hosts")
 	if err != nil {
@@ -416,6 +416,14 @@ func (container *Container) buildHostnameAndHostsFiles(IP string) error {
 	return etchosts.Build(container.HostsPath, IP, container.Config.Hostname, container.Config.Domainname, &extraContent)
 }
 
+func (container *Container) buildHostnameAndHostsFiles(IP string) error {
+	if err := container.buildHostnameFile(); err != nil {
+		return err
+	}
+
+	return container.buildHostsFiles(IP)
+}
+
 func (container *Container) allocateNetwork() error {
 	mode := container.hostConfig.NetworkMode
 	if container.Config.NetworkDisabled || mode.IsContainer() || mode.IsHost() {
@@ -878,6 +886,26 @@ func (container *Container) setupContainerDns() error {
 	return ioutil.WriteFile(container.ResolvConfPath, resolvConf, 0644)
 }
 
+func (container *Container) updateParentsHosts() error {
+	parents, err := container.daemon.Parents(container.Name)
+	if err != nil {
+		return err
+	}
+	for _, cid := range parents {
+		if cid == "0" {
+			continue
+		}
+
+		c := container.daemon.Get(cid)
+		if c != nil && !container.daemon.config.DisableNetwork && !container.hostConfig.NetworkMode.IsContainer() && !container.hostConfig.NetworkMode.IsHost() {
+			if err := etchosts.Update(c.HostsPath, container.NetworkSettings.IPAddress, container.Name[1:]); err != nil {
+				return fmt.Errorf("Failed to update /etc/hosts in parent container: %v", err)
+			}
+		}
+	}
+	return nil
+}
+
 func (container *Container) initializeNetworking() error {
 	var err error
 	if container.hostConfig.NetworkMode.IsHost() {

daemon/daemon.go

@@ -621,6 +621,15 @@ func (daemon *Daemon) Children(name string) (map[string]*Container, error) {
 	return children, nil
 }
 
+func (daemon *Daemon) Parents(name string) ([]string, error) {
+	name, err := GetFullContainerName(name)
+	if err != nil {
+		return nil, err
+	}
+
+	return daemon.containerGraph.Parents(name)
+}
+
 func (daemon *Daemon) RegisterLink(parent, child *Container, alias string) error {
 	fullName := path.Join(parent.Name, alias)
 	if !daemon.containerGraph.Exists(fullName) {