Initial commit

f3d86fea · mohammad.salama · f3d86fea · f3d86fea · f3d86fea · f3d86fea
Commit f3d86fea authored Mar 01, 2024 by mohammad.salama
6 changed files
--- a/Config.json
+++ b/Config.json
+{
+    "listenPort": ":8080",
+    "healthCheckInterval": "5s",
+    "servers": [
+        "http://localhost:8001", 
+        "http://localhost:8002"
+    ]
+}
\ No newline at end of file
--- a/LoadBalancer.go
+++ b/LoadBalancer.go
+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync"
+	"time"
+)
+
+type Server struct {
+	URL               *url.URL   // URL of the backend server.
+	ActiveConnections int        // Count of active connections
+	Mutex             sync.Mutex // A mutex for safe concurrency
+	Healthy           bool
+}
+
+type Config struct {
+	HealthCheckInterval string   `json:"healthCheckInterval"`
+	Servers             []string `json:"servers"`
+	ListenPort          string   `json:"listenPort"`
+}
+
+func loadConfig(file string) (Config, error) {
+	var config Config
+
+	bytes, err := ioutil.ReadFile(file)
+	if err != nil {
+		return config, err
+	}
+
+	err = json.Unmarshal(bytes, &config)
+	if err != nil {
+		return config, err
+	}
+
+	return config, nil
+}
+
+func nextServerLeastActive(servers []*Server) *Server {
+	leastActiveConnections := -1
+	leastActiveServer := servers[0]
+	for _, server := range servers {
+		server.Mutex.Lock()
+		if (server.ActiveConnections < leastActiveConnections || leastActiveConnections == -1) && server.Healthy {
+			leastActiveConnections = server.ActiveConnections
+			leastActiveServer = server
+		}
+		server.Mutex.Unlock()
+	}
+
+	return leastActiveServer
+}
+
+func (s *Server) Proxy() *httputil.ReverseProxy {
+	return httputil.NewSingleHostReverseProxy(s.URL)
+}
+
+func checkServer(s *Server , healthCheckInterval time.Duration) {
+	for range time.Tick(healthCheckInterval) {
+		res, err := http.Get(s.URL.String())
+		if err != nil || res.StatusCode >= 500 {
+			s.Healthy = false
+		} else {
+			s.Healthy = true
+		}
+	}
+}
+
+func performHealthChecks(servers []*Server , healthCheckInterval time.Duration) {
+	for _, server := range servers {
+		go checkServer(server , healthCheckInterval)
+	}
+}
+
+func main() {
+	config, err := loadConfig("config.json")
+
+	if err != nil {
+		log.Fatalf("Error loading configuration: %s", err.Error())
+	}
+
+	healthCheckInterval, err := time.ParseDuration(config.HealthCheckInterval)
+
+	if err != nil {
+		log.Fatalf("Invalid health check interval: %s", err.Error())
+	}
+
+	var servers []*Server
+	for _, serverUrl := range config.Servers {
+		u, _ := url.Parse(serverUrl)
+		servers = append(servers, &Server{URL: u})
+	}
+
+	performHealthChecks(servers , healthCheckInterval)
+
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		server := nextServerLeastActive(servers)
+		server.Mutex.Lock()
+		server.ActiveConnections++
+		server.Mutex.Unlock()
+		server.Proxy().ServeHTTP(w, r)
+		server.Mutex.Lock()
+		server.ActiveConnections--
+		server.Mutex.Unlock()
+	})
+
+	log.Println("Starting server on port", config.ListenPort)
+
+	err = http.ListenAndServe(config.ListenPort, nil)
+
+	if err != nil {
+		log.Fatalf("Error starting server: %s\n", err)
+	}
+}
--- a/Web Jar/WebServer.jar
+++ b/Web Jar/WebServer.jar
--- a/Web Jar/index8001.html
+++ b/Web Jar/index8001.html
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Hello from Server "1"</title>
+    <style>
+        body, html {
+            height: 100%;
+            margin: 0;
+            display: flex;
+            align-items: center;
+            justify-content: center;
+            text-align: center;
+        }
+
+        .flashy-text {
+            font-size: 48px;
+            animation: flash 2s infinite;
+        }
+
+        @keyframes flash {
+            0% { opacity: 1; }
+            50% { opacity: 0; }
+            100% { opacity: 1; }
+        }
+    </style>
+</head>
+<body>
+    <div class="flashy-text">
+        Hello from Server "1 - One"
+    </div>
+</body>
+</html>
\ No newline at end of file
--- a/Web Jar/index8002.html
+++ b/Web Jar/index8002.html
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Hello from Server "2"</title>
+    <style>
+        body, html {
+            height: 100%;
+            margin: 0;
+            display: flex;
+            align-items: center;
+            justify-content: center;
+            text-align: center;
+        }
+
+        .flashy-text {
+            font-size: 48px;
+            animation: flash 2s infinite;
+        }
+
+        @keyframes flash {
+            0% { opacity: 1; }
+            50% { opacity: 0; }
+            100% { opacity: 1; }
+        }
+    </style>
+</head>
+<body>
+    <div class="flashy-text">
+        Hello from Server "2 - Two"
+    </div>
+</body>
+</html>
\ No newline at end of file
--- a/Web Jar/index8003.html
+++ b/Web Jar/index8003.html
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Hello from Server "3"</title>
+    <style>
+        body, html {
+            height: 100%;
+            margin: 0;
+            display: flex;
+            align-items: center;
+            justify-content: center;
+            text-align: center;
+        }
+
+        .flashy-text {
+            font-size: 48px;
+            animation: flash 2s infinite;
+        }
+
+        @keyframes flash {
+            0% { opacity: 1; }
+            50% { opacity: 0; }
+            100% { opacity: 1; }
+        }
+    </style>
+</head>
+<body>
+    <div class="flashy-text">
+        Hello from Server "3 - Three"
+    </div>
+</body>
+</html>
\ No newline at end of file