ArgoTunnel.go

package main

import (
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"regexp"
	"strings"
	"sync"
	"time"
)

const cf string = `https://.+trycloudflare.com`

var link = ""
var wg sync.WaitGroup

func GetLink(w io.Writer, r io.Reader) {
	defer wg.Done()
	var wait = false
	defer wg.Done()
	match := regexp.MustCompile(cf)
	var out []byte
	buf := make([]byte, 1024, 1024)

	for {
		n, err := r.Read(buf[:])
		if n > 0 {
			d := buf[:n]
			out = append(out, d...)
			_, err := w.Write(d)
			if err != nil {
				return
			}
		}
		if wait == false {
			lines := strings.Split(string(out), "\n")
			for _, s := range lines {
				matches := match.FindAllString(s, -1)
				for _, f := range matches {
					if len(f) > 20 {
						link = f
						if match.MatchString(f) {
							wait = true
						}
					}
				}
			}
		}
		if err != nil {
			if err == io.EOF {
				err = nil
			}
		}
	}
}

func CF(cmd *exec.Cmd) {
	stdoutIn, _ := cmd.StdoutPipe()
	stderrIn, _ := cmd.StderrPipe()
	err := cmd.Start()
	if err != nil {
		log.Fatalf("cmd.Start() failed with '%s'\n", err)
	}
	wg.Add(1)
	go GetLink(os.Stdout, stdoutIn)
	wg.Add(1)
	go GetLink(os.Stderr, stderrIn)
}

func main() {
	cmd := exec.Command("cloudflared", "tunnel", "--url", "localhost:9999", "--no-autoupdate")
	go CF(cmd)
	for len(link) == 0 {
		time.Sleep(time.Second)
	}
	for {
		time.Sleep(time.Second)
		fmt.Println(link)
	}
}

Wait for the link to get generated and use the variable link as needed