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Update and rename main.go #15

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Update and rename main.go #15

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69 changes: 54 additions & 15 deletions main.go → updated main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package main
import (
"bytes"
"context"
"encoding/json"
"io"
"loadbalancer/lib"
"log"
Expand All @@ -13,6 +14,8 @@ import (
"os/signal"
"syscall"
"time"

gomail "gopkg.in/gomail.v2"
)

type RetryType int
Expand All @@ -25,7 +28,7 @@ const (

var serverPool lib.ServerPool

// this function creates a log file if it does not already exist
// Initialize logger
func InitLogger() (*os.File, error) {
logFile, err := os.OpenFile("loadbalancer.log", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666)
if err != nil {
Expand All @@ -36,43 +39,44 @@ func InitLogger() (*os.File, error) {
return logFile, nil
}

// this function logs details about incoming requests
// Log incoming requests
func LogRequest(r *http.Request) {
clientIp := r.RemoteAddr
method := r.Method
url := r.URL.String()
log.Printf("Received request from %s : %s, %s ", clientIp, method, url)
}

// this function logs which backend is selected
// Log backend selection
func LogBackendSelection(backendURL string) {
log.Printf("Routing request to backend: %s", backendURL)
}

// this function measures the time taken to process a request
// Track response time
func TrackresponseTime(start time.Time, backendURL string) {
duration := time.Since(start)
log.Printf("Request to backend %s took %v", backendURL, duration)
}

// this functions returns the retry count from the context
// Get retry count from context
func GetRetryFromContext(r *http.Request) int {
if retry, ok := r.Context().Value(Retry).(int); ok {
return retry
}
return 0
}

// this function returns the attempts from the context
// Get attempts from context
func GetAttemptsFromContext(r *http.Request) int {
if attempts, ok := r.Context().Value(Attempts).(int); ok {
return attempts
}
return 1
}

// Load balancer handler
func lb(w http.ResponseWriter, r *http.Request) {
//log the request
// Log the request
LogRequest(r)

peer := serverPool.GetNextPeer()
Expand All @@ -92,26 +96,59 @@ func lb(w http.ResponseWriter, r *http.Request) {
http.Error(w, "Service not available", http.StatusServiceUnavailable)
}

func main() {
// Health check function
func healthCheck() {
for {
for _, backend := range serverPool.Backends {
resp, err := http.Get(backend.URL.String())
if err != nil || resp.StatusCode != http.StatusOK {
log.Printf("Server down: %s, sending alert.", backend.URL.String())
sendAlert(backend.URL.String())
serverPool.MarkDownTheServer(backend.URL, true) // Mark the server as down
} else {
serverPool.MarkDownTheServer(backend.URL, false) // Mark the server as up if it's responding
}
if resp != nil {
resp.Body.Close()
}
}
time.Sleep(30 * time.Second) // Check every 30 seconds
}
}

// Send alert function
func sendAlert(serverURL string) {
m := gomail.NewMessage()
m.SetHeader("From", "[email protected]") // Replace with your email
m.SetHeader("To", "[email protected]") // Replace with recipient email
m.SetHeader("Subject", "Alert: Server is down")
m.SetBody("text/plain", "The server at "+serverURL+" is unresponsive.")

//Initialize logger
d := gomail.NewDialer("smtp.example.com", 587, "[email protected]", "your-email-password") // Replace with your SMTP details

if err := d.DialAndSend(m); err != nil {
log.Printf("Failed to send alert: %v", err)
}
}

func main() {
// Initialize logger
logfile, err := InitLogger()
if err != nil {
log.Fatalf("Error initializing logger: %v", err)
}

defer logfile.Close()

// get file name from argument
// Get file name from argument
arg := os.Args
if len(arg) != 2 {
log.Fatal("usage go run main.go <config-file>'")
log.Fatal("usage: go run main.go <config-file>")
}

// declare slice for backend server
// Declare slice for backend servers
backendservers := []string{}

// read the config file and get the host and url.
// Read the config file and get the host and URL.
var config lib.Config
config, err = lib.ReadConfig(arg[1])
if err != nil {
Expand All @@ -129,7 +166,6 @@ func main() {
for _, backend := range backendservers {
log.Println("Load balancing to the backend server: ", backend)
be, err := url.Parse(backend)
log.Println(be)
if err != nil {
log.Println("Error parsing URL")
}
Expand Down Expand Up @@ -176,6 +212,9 @@ func main() {
})
}

// Start the health check in a separate goroutine
go healthCheck()

server := &http.Server{
Addr: ":8000",
WriteTimeout: 15 * time.Second,
Expand Down