Add DNS support for PWD instances (#94)

* Add DNS support for PWD instances

* Store IP address of PWD in all session networks and restore it with the
same IP address

* Remove unnecesary print

* Change url format to pwd<ip>-port for better DNS filtering

* Make PWD listen on 80 and 443 for DNS resolve to work

services/docker.go

@@ -135,17 +135,33 @@ func CreateNetwork(name string) error {
 
 	return nil
 }
-func ConnectNetwork(containerId, networkId string) error {
-	err := c.NetworkConnect(context.Background(), networkId, containerId, &network.EndpointSettings{})
+func ConnectNetwork(containerId, networkId, ip string) (string, error) {
+	settings := &network.EndpointSettings{}
+	if ip != "" {
+		settings.IPAddress = ip
+	}
+	err := c.NetworkConnect(context.Background(), networkId, containerId, settings)
 
 	if err != nil && !strings.Contains(err.Error(), "already exists") {
 		log.Printf("Connection container to network err [%s]\n", err)
 
-		return err
+		return "", err
 	}
 
-	return nil
+	// Obtain the IP of the PWD container in this network
+	container, err := c.ContainerInspect(context.Background(), containerId)
+	if err != nil {
+		return "", err
+	}
+
+	n, found := container.NetworkSettings.Networks[networkId]
+	if !found {
+		return "", fmt.Errorf("Container [%s] connected to the network [%s] but couldn't obtain it's IP address", containerId, networkId)
+	}
+
+	return n.IPAddress, nil
 }
+
 func DisconnectNetwork(containerId, networkId string) error {
 	err := c.NetworkDisconnect(context.Background(), networkId, containerId, true)
 
@@ -217,7 +233,15 @@ func CreateInstance(session *Session, dindImage string) (*Instance, error) {
 			break
 		}
 	}
-	conf := &container.Config{Hostname: nodeName, Image: dindImage, Tty: true, OpenStdin: true, AttachStdin: true, AttachStdout: true, AttachStderr: true}
+	conf := &container.Config{Hostname: nodeName,
+		Image:        dindImage,
+		Tty:          true,
+		OpenStdin:    true,
+		AttachStdin:  true,
+		AttachStdout: true,
+		AttachStderr: true,
+		Env:          []string{fmt.Sprintf("PWD_IP_ADDRESS=%s", session.PwdIpAddress)},
+	}
 	networkConf := &network.NetworkingConfig{
 		map[string]*network.EndpointSettings{
 			session.Id: &network.EndpointSettings{Aliases: []string{nodeName}},

services/session.go

@@ -42,14 +42,15 @@ func init() {
 var wsServer *socketio.Server
 
 type Session struct {
-	rw        sync.Mutex
-	Id        string               `json:"id"`
-	Instances map[string]*Instance `json:"instances"`
-	clients   []*Client            `json:"-"`
-	CreatedAt time.Time            `json:"created_at"`
-	ExpiresAt time.Time            `json:"expires_at"`
-	scheduled bool                 `json:"-"`
-	ticker    *time.Ticker         `json:"-"`
+	rw           sync.Mutex
+	Id           string               `json:"id"`
+	Instances    map[string]*Instance `json:"instances"`
+	clients      []*Client            `json:"-"`
+	CreatedAt    time.Time            `json:"created_at"`
+	ExpiresAt    time.Time            `json:"expires_at"`
+	scheduled    bool                 `json:"-"`
+	ticker       *time.Ticker         `json:"-"`
+	PwdIpAddress string               `json:"pwd_ip_address"`
 }
 
 func (s *Session) Lock() {
@@ -239,10 +240,12 @@ func NewSession(duration time.Duration) (*Session, error) {
 	log.Printf("Network [%s] created for session [%s]\n", s.Id, s.Id)
 
 	// Connect PWD daemon to the new network
-	if err := ConnectNetwork("pwd", s.Id); err != nil {
+	ip, err := ConnectNetwork("pwd", s.Id, "")
+	if err != nil {
 		log.Println("ERROR NETWORKING")
 		return nil, err
 	}
+	s.PwdIpAddress = ip
 	log.Printf("Connected pwd to network [%s]\n", s.Id)
 
 	// Schedule peridic tasks execution
@@ -315,7 +318,10 @@ func LoadSessionsFromDisk() error {
 			}
 
 			// Connect PWD daemon to the new network
-			if err := ConnectNetwork("pwd", s.Id); err != nil {
+			if s.PwdIpAddress == "" {
+				log.Fatal("Cannot load stored sessions as they don't have the pwd ip address stored with them")
+			}
+			if _, err := ConnectNetwork("pwd", s.Id, s.PwdIpAddress); err != nil {
 				if strings.Contains(err.Error(), "Could not attach to network") {
 					log.Printf("Network for session [%s] doesn't exist. Removing all instances and session.", s.Id)
 					CloseSession(s)