Scaling (#109)

Make PWD scalable

handlers/get_session.go

@@ -2,7 +2,6 @@ package handlers
 
 import (
 	"encoding/json"
-	"log"
 	"net/http"
 
 	"github.com/franela/play-with-docker/services"
@@ -12,7 +11,6 @@ import (
 func GetSession(rw http.ResponseWriter, req *http.Request) {
 	vars := mux.Vars(req)
 	sessionId := vars["sessionId"]
-	log.Println(sessionId)
 
 	session := services.GetSession(sessionId)
 

handlers/new_session.go

@@ -1,13 +1,20 @@
 package handlers
 
 import (
+	"encoding/json"
 	"fmt"
 	"log"
 	"net/http"
 
+	"github.com/franela/play-with-docker/config"
 	"github.com/franela/play-with-docker/services"
 )
 
+type NewSessionResponse struct {
+	SessionId string `json:"session_id"`
+	Hostname  string `json:"hostname"`
+}
+
 func NewSession(rw http.ResponseWriter, req *http.Request) {
 	req.ParseForm()
 	if !services.IsHuman(req) {
@@ -25,11 +32,15 @@ func NewSession(rw http.ResponseWriter, req *http.Request) {
 		log.Println(err)
 		//TODO: Return some error code
 	} else {
+
+		hostname := fmt.Sprintf("%s.%s", config.PWDCName, req.Host)
 		// If request is not a form, return sessionId in the body
 		if req.Header.Get("X-Requested-With") == "XMLHttpRequest" {
-			rw.Write([]byte(s.Id))
+			resp := NewSessionResponse{SessionId: s.Id, Hostname: hostname}
+			rw.Header().Set("Content-Type", "application/json")
+			json.NewEncoder(rw).Encode(resp)
 			return
 		}
-		http.Redirect(rw, req, fmt.Sprintf("/p/%s", s.Id), http.StatusFound)
+		http.Redirect(rw, req, fmt.Sprintf("http://%s/p/%s", hostname, s.Id), http.StatusFound)
 	}
 }

handlers/ping.go

@@ -1,6 +1,23 @@
 package handlers
 
-import "net/http"
+import (
+	"log"
+	"net/http"
+
+	"github.com/franela/play-with-docker/config"
+	"github.com/shirou/gopsutil/load"
+)
 
 func Ping(rw http.ResponseWriter, req *http.Request) {
+	// Get system load average of the last 5 minutes and compare it against a threashold.
+
+	a, err := load.Avg()
+	if err != nil {
+		log.Println("Cannot get system load average!", err)
+	} else {
+		if a.Load5 > config.MaxLoadAvg {
+			log.Printf("System load average is too high [%f]\n", a.Load5)
+			rw.WriteHeader(http.StatusInsufficientStorage)
+		}
+	}
 }