Add support for setting alias when creatign instance. (#140)

* Add support for setting alias when creatign instance.

The POST to create a instance now provides an `alias` field which
then can be used to access the instance services through the following
URL:

`http://<alias>-<short_session>-<port>.<tld>`

When creating a session you can now send an `alias`

* Remove unnecessary function

* Add alias support for DNS resolution

handlers/dns.go

@@ -8,16 +8,20 @@ import (
 	"strings"
 
 	"github.com/miekg/dns"
+	"github.com/play-with-docker/play-with-docker/services"
 )
 
-var dnsFilter = regexp.MustCompile(`pwd[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}`)
+var dnsFilter = regexp.MustCompile(`^.*pwd([0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}_[0-9]{1,3}(?:-[0-9]{1,5})?)\..*$`)
+var aliasFilter = regexp.MustCompile(`^.*pwd(.*?)-(.*?)[\.-].*`)
 
 func DnsRequest(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"), "-")
+
+		match := dnsFilter.FindStringSubmatch(question)
+
+		tldChunks := strings.Split(match[1], "-")
 		ip := strings.Replace(tldChunks[0], "_", ".", -1)
 
 		m := new(dns.Msg)
@@ -31,6 +35,25 @@ func DnsRequest(w dns.ResponseWriter, r *dns.Msg) {
 		m.Answer = append(m.Answer, a)
 		w.WriteMsg(m)
 		return
+	} else if len(r.Question) > 0 && aliasFilter.MatchString(r.Question[0].Name) {
+		// this is something we know about and we should try to handle
+		question := r.Question[0].Name
+
+		match := aliasFilter.FindStringSubmatch(question)
+
+		i := services.FindInstanceByAlias(match[2], match[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, i.IP))
+		if err != nil {
+			log.Fatal(err)
+		}
+		m.Answer = append(m.Answer, a)
+		w.WriteMsg(m)
+		return
 	} else {
 		if len(r.Question) > 0 {
 			question := r.Question[0].Name

handlers/new_instance.go

@@ -13,7 +13,7 @@ func NewInstance(rw http.ResponseWriter, req *http.Request) {
 	vars := mux.Vars(req)
 	sessionId := vars["sessionId"]
 
-	body := struct{ ImageName string }{}
+	body := struct{ ImageName, Alias string }{}
 
 	json.NewDecoder(req.Body).Decode(&body)
 
@@ -26,7 +26,7 @@ func NewInstance(rw http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	i, err := services.NewInstance(s, body.ImageName)
+	i, err := services.NewInstance(s, body.ImageName, body.Alias)
 	if err != nil {
 		log.Println(err)
 		rw.WriteHeader(http.StatusInternalServerError)

handlers/reverseproxy.go

@@ -11,11 +11,14 @@ import (
 
 	"github.com/gorilla/mux"
 	"github.com/play-with-docker/play-with-docker/config"
+	"github.com/play-with-docker/play-with-docker/services"
 )
 
 func getTargetInfo(vars map[string]string, req *http.Request) (string, string) {
 	node := vars["node"]
 	port := vars["port"]
+	alias := vars["alias"]
+	sessionPrefix := vars["session"]
 	hostPort := strings.Split(req.Host, ":")
 
 	// give priority to the URL host port
@@ -25,6 +28,14 @@ func getTargetInfo(vars map[string]string, req *http.Request) (string, string) {
 		port = "80"
 	}
 
+	if alias != "" {
+		instance := services.FindInstanceByAlias(sessionPrefix, alias)
+		if instance != nil {
+			node = instance.IP
+			return node, port
+		}
+	}
+
 	if strings.HasPrefix(node, "pwd") {
 		// Node is actually an ip, need to convert underscores by dots.
 		ip := strings.Replace(strings.TrimPrefix(node, "pwd"), "_", ".", -1)