commit

httpserver1/go.mod

+module go/hello
+
+go 1.22.0

httpserver1/hello.go

+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "Hello from Server 1!")
+	})
+
+	fmt.Println("Server 1 listening on port 8081...")
+	http.ListenAndServe(":8081", nil)
+}

httpserver2/go.mod

+module go/hello
+
+go 1.22.0

httpserver2/hello.go

+package main
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func main() {
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintf(w, "Hello from Server 2!")
+	})
+
+	fmt.Println("Server 2 listening on port 8082...")
+	http.ListenAndServe(":8082", nil)
+}

load_balancer/config.json

+{
+    "listenPort": ":8000",
+    "healthCheckInterval": "5s",
+    "servers": [
+        "http://localhost:8081", 
+        "http://localhost:8082"
+    ]
+}

load_balancer/go.mod

+module go/load_balancer
+
+go 1.22.0

load_balancer/load_balancer.go

+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"sync"
+	"time"
+)
+
+// Server represents a backend server
+type Server struct {
+	URL               *url.URL // URL of the backend server.
+	ActiveConnections int      // Count of active connections
+	Mutex             sync.Mutex
+	Healthy           bool
+}
+
+// Config represents the configuration for the load balancer
+type Config struct {
+	HealthCheckInterval string   `json:"healthCheckInterval"`
+	Servers             []string `json:"servers"`
+	ListenPort          string   `json:"listenPort"`
+}
+
+// Load configuration from file
+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
+}
+
+// Select the server with the least active connections
+func nextServerLeastActive(servers []*Server) *Server {
+	leastActiveConnections := -1
+	var leastActiveServer *Server
+
+	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 main() {
+	// Load configuration
+	config, err := loadConfig("C:\\Users\\Abdullah\\Desktop\\go\\config.json")
+		if err != nil {
+		log.Fatalf("Error loading configuration: %s", err.Error())
+	}
+
+	// Parse health check interval
+	healthCheckInterval, err := time.ParseDuration(config.HealthCheckInterval)
+	if err != nil {
+		log.Fatalf("Invalid health check interval: %s", err.Error())
+	}
+
+	// Initialize servers
+	var servers []*Server
+	for _, serverURL := range config.Servers {
+		u, _ := url.Parse(serverURL)
+		servers = append(servers, &Server{URL: u})
+	}
+
+	// Start health checks for each server
+	for _, server := range servers {
+		go func(s *Server) {
+			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
+				}
+			}
+		}(server)
+	}
+
+	// Handle incoming requests
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		server := nextServerLeastActive(servers)
+		if server != nil {
+			server.Mutex.Lock()
+			server.ActiveConnections++
+			server.Mutex.Unlock()
+			defer func() {
+				server.Mutex.Lock()
+				server.ActiveConnections--
+				server.Mutex.Unlock()
+			}()
+			serverProxy := httputil.NewSingleHostReverseProxy(server.URL)
+			serverProxy.ServeHTTP(w, r)
+		} else {
+			http.Error(w, "No healthy server available", http.StatusServiceUnavailable)
+		}
+	})
+
+	// Start the load balancer
+	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)
+	}
+}
+