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

Dockerfile.dind

@@ -2,8 +2,9 @@ FROM docker:1.13.1-dind
 
 RUN apk add --no-cache git tmux py2-pip apache2-utils vim build-base gettext-dev curl bash
 
+ENV COMPOSE_VERSION=1.11.1
 # Install Compose and Machine
-RUN pip install docker-compose==1.10.0-rc1
+RUN pip install docker-compose==${COMPOSE_VERSION}
 RUN curl -L https://github.com/docker/machine/releases/download/v0.9.0-rc1/docker-machine-Linux-x86_64 \
     -o /usr/bin/docker-machine && chmod +x /usr/bin/docker-machine
 
@@ -34,6 +35,6 @@ WORKDIR /root
 CMD cat /etc/hosts >/etc/hosts.bak && \
     sed 's/^::1.*//' /etc/hosts.bak > /etc/hosts && \
     dockerd --experimental -g /graph --host=unix:///var/run/docker.sock --host=tcp://0.0.0.0:2375 \
-            --storage-driver=$DOCKER_STORAGE_DRIVER &>/docker.log & \
+            --storage-driver=$DOCKER_STORAGE_DRIVER --dns $PWD_IP_ADDRESS --dns 8.8.8.8 &>/docker.log & \
     while true ; do /bin/bash ; done
 # ... and then put a shell in the foreground, restarting it if it exits

README.md

@@ -52,5 +52,5 @@ Notes:
 
 ~~We're planning to setup a reverse proxy that handles redirection automatically, in the meantime you can use [ngrok](https://ngrok.com) within PWD running `docker run --name supergrok -d jpetazzo/supergrok` then `docker logs --follow supergrok` , it will give you a ngrok URL, now you can go to that URL and add the IP+port that you want to connect to… e.g. if your PWD instance is 10.0.42.3, you can go to http://xxxxxx.ngrok.io/10.0.42.3:8000 (where the xxxxxx is given to you in the supergrok logs).~~
 
-If you need to access your services from outside, use the following URL pattern `http://ip<underscore_ip>-<port>.play-with-docker.com` (i.e: http://ip10_2_135_3-80.play-with-docker.com/).
+If you need to access your services from outside, use the following URL pattern `http://pwd<underscore_ip>-<port>.play-with-docker.com` (i.e: http://pwd10_2_135_3-80.play-with-docker.com/).
 

api.go

@@ -6,6 +6,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"regexp"
 	"strings"
 
 	"github.com/franela/play-with-docker/config"
@@ -14,6 +15,7 @@ import (
 	"github.com/franela/play-with-docker/templates"
 	gh "github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
+	"github.com/miekg/dns"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/urfave/negroni"
 	"github.com/yhat/wsutil"
@@ -25,6 +27,16 @@ func main() {
 
 	bypassCaptcha := len(os.Getenv("GOOGLE_RECAPTCHA_DISABLED")) > 0
 
+	// Start the DNS server
+	dnsServer := &dns.Server{Addr: ":53", Net: "udp"}
+	dns.HandleFunc(".", handleDnsRequest)
+	go func() {
+		err := dnsServer.ListenAndServe()
+		if err != nil {
+			log.Fatal(err)
+		}
+	}()
+
 	server := services.CreateWSServer()
 	server.On("connection", handlers.WS)
 	server.On("error", handlers.WSError)
@@ -49,8 +61,8 @@ func main() {
 	}
 
 	// Specific routes
-	r.Host(`{node:ip[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}}-{port:[0-9]*}.{tld:.*}`).HandlerFunc(proxyMultiplexer)
-	r.Host(`{node:ip[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}}.{tld:.*}`).HandlerFunc(proxyMultiplexer)
+	r.Host(`{node:pwd[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}}-{port:[0-9]*}.{tld:.*}`).HandlerFunc(proxyMultiplexer)
+	r.Host(`{node:pwd[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}}.{tld:.*}`).HandlerFunc(proxyMultiplexer)
 	r.HandleFunc("/ping", handlers.Ping).Methods("GET")
 	r.HandleFunc("/sessions/{sessionId}", handlers.GetSession).Methods("GET")
 	r.Handle("/sessions/{sessionId}/instances", http.HandlerFunc(handlers.NewInstance)).Methods("POST")
@@ -98,7 +110,7 @@ func main() {
 
 	ssl := mux.NewRouter()
 	sslProxyHandler := handlers.NewSSLDaemonHandler()
-	ssl.Host(`{node:ip[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}}-2375.{tld:.*}`).Handler(sslProxyHandler)
+	ssl.Host(`{node:pwd[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}}-2375.{tld:.*}`).Handler(sslProxyHandler)
 	log.Println("Listening TLS on port " + config.SSLPortNumber)
 
 	s := &http.Server{Addr: "0.0.0.0:" + config.SSLPortNumber, Handler: ssl}
@@ -107,7 +119,7 @@ func main() {
 
 		chunks := strings.Split(clientHello.ServerName, ".")
 		chunks = strings.Split(chunks[0], "-")
-		ip := strings.Replace(strings.TrimPrefix(chunks[0], "ip"), "_", ".", -1)
+		ip := strings.Replace(strings.TrimPrefix(chunks[0], "pwd"), "_", ".", -1)
 		i := services.FindInstanceByIP(ip)
 		if i == nil {
 			return nil, fmt.Errorf("Instance %s doesn't exist", clientHello.ServerName)
@@ -119,3 +131,31 @@ func main() {
 	}
 	log.Fatal(s.ListenAndServeTLS("", ""))
 }
+
+var dnsFilter = regexp.MustCompile(`pwd[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}`)
+
+func handleDnsRequest(w dns.ResponseWriter, r *dns.Msg) {
+	if len(r.Question) > 0 && dnsFilter.MatchString(r.Question[0].Name) {
+		// this is something we know about and we should try to handle
+		question := r.Question[0].Name
+		domainChunks := strings.Split(question, ".")
+		tldChunks := strings.Split(strings.TrimPrefix(domainChunks[0], "pwd"), "-")
+		ip := strings.Replace(tldChunks[0], "_", ".", -1)
+
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Authoritative = true
+		m.RecursionAvailable = true
+		a, err := dns.NewRR(fmt.Sprintf("%s 60 IN A %s", question, ip))
+		if err != nil {
+			log.Fatal(err)
+		}
+		m.Answer = append(m.Answer, a)
+		w.WriteMsg(m)
+		return
+	} else {
+		// we have no information about this and we are not a recursive dns server, so we just fail so the client can fallback to the next dns server it has configured
+		dns.HandleFailed(w, r)
+		return
+	}
+}

docker-compose.yml

@@ -9,8 +9,8 @@ services:
         command: /bin/sh -c 'cd /go/src/github.com/franela/play-with-docker; go run api.go'
         ports:
             # app exposes port 3000
-            - "3000:3000"
-            - "3001:3001"
+            - "80:3000"
+            - "443:3001"
         volumes:
             # since this app creates networks and launches containers, we need to talk to docker daemon
             - /var/run/docker.sock:/var/run/docker.sock

handlers/reverseproxy.go

@@ -40,9 +40,9 @@ func NewMultipleHostReverseProxy() *httputil.ReverseProxy {
 			port = "80"
 		}
 
-		if strings.HasPrefix(node, "ip") {
+		if strings.HasPrefix(node, "pwd") {
 			// Node is actually an ip, need to convert underscores by dots.
-			ip := strings.Replace(strings.TrimPrefix(node, "ip"), "_", ".", -1)
+			ip := strings.Replace(strings.TrimPrefix(node, "pwd"), "_", ".", -1)
 
 			if net.ParseIP(ip) == nil {
 				// Not a valid IP, so treat this is a hostname.
@@ -69,9 +69,9 @@ func NewSSLDaemonHandler() *httputil.ReverseProxy {
 	director := func(req *http.Request) {
 		v := mux.Vars(req)
 		node := v["node"]
-		if strings.HasPrefix(node, "ip") {
+		if strings.HasPrefix(node, "pwd") {
 			// Node is actually an ip, need to convert underscores by dots.
-			ip := strings.Replace(strings.TrimPrefix(node, "ip"), "_", ".", -1)
+			ip := strings.Replace(strings.TrimPrefix(node, "pwd"), "_", ".", -1)
 
 			if net.ParseIP(ip) == nil {
 				// Not a valid IP, so treat this is a hostname.

handlers/websocket_reverseproxy.go

@@ -29,9 +29,9 @@ func NewMultipleHostWebsocketReverseProxy() *wsutil.ReverseProxy {
 			port = "80"
 		}
 
-		if strings.HasPrefix(node, "ip") {
+		if strings.HasPrefix(node, "pwd") {
 			// Node is actually an ip, need to convert underscores by dots.
-			ip := strings.Replace(strings.TrimPrefix(node, "ip"), "_", ".", -1)
+			ip := strings.Replace(strings.TrimPrefix(node, "pwd"), "_", ".", -1)
 
 			if net.ParseIP(ip) == nil {
 				// Not a valid IP, so treat this is a hostname.

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

@@ -50,6 +50,7 @@ type Session struct {
 	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)

www/assets/app.js

@@ -176,7 +176,7 @@
         }
 
         $scope.getProxyUrl = function(instance, port) {
-            var url = window.location.protocol + '//ip' + instance.ip.replace(/\./g, '_') + '-' + port + '.' + window.location.host;
+            var url = window.location.protocol + '//pwd' + instance.ip.replace(/\./g, '_') + '-' + port + '.' + window.location.host;
 
             return url;
         }