jenkins print login error

gistfile1.txt

package main

import (
 "fmt"
 "io/ioutil"
 "net/http"
 "net/http/cookiejar"
 "net/url"
)

func main() {
 // Create an HTTP client with a cookie jar
 jar, err := cookiejar.New(nil)
 if err != nil {
  panic(err)
 }
 client := &http.Client{Jar: jar}

 // Authenticate to Jenkins
 username := "your-username"
 password := "your-password"
 loginURL := "http://jenkins.example.com/j_acegi_security_check"
 data := url.Values{
  "j_username": {username},
  "j_password": {password},
 }
 req, err := http.NewRequest("POST", loginURL, strings.NewReader(data.Encode()))
 if err != nil {
  panic(err)
 }
 req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 resp, err := client.Do(req)
 if err != nil {
  panic(err)
 }
 defer resp.Body.Close()

 // Print the response body
 body, err := ioutil.ReadAll(resp.Body)
 if err != nil {
  panic(err)
 }
 fmt.Println(string(body))

 // Get the session ID from the cookie
 for _, cookie := range jar.Cookies(resp.Request.URL) {
  if cookie.Name == "JSESSIONID" {
   fmt.Println("Session ID:", cookie.Value)
   break
  }
 }
}