Program to test the time it takes to start a virtual machine.

main.go

/*

Program to test the time it takes to start a virtual machine.

USAGE:

./main -vm vm-name -address 192.168.120.150:22 -user username -key ~/.ssh/id_rsa

*/

package main

import (
	"flag"
	"fmt"
	"os"
	"os/exec"
	"time"

	"golang.org/x/crypto/ssh"
)

func startVM(vmName string) error {
	cmd := exec.Command("virsh", "start", vmName)
	return cmd.Run()
}

func waitForSSH(address, user, keyPath string) (time.Duration, error) {
	start := time.Now()

	for {
		key, err := os.ReadFile(keyPath)
		if err != nil {
			return 0, fmt.Errorf("failed to read SSH key: %v", err)
		}

		signer, err := ssh.ParsePrivateKey(key)
		if err != nil {
			return 0, fmt.Errorf("failed to parse SSH key: %v", err)
		}

		config := &ssh.ClientConfig{
			User: user,
			Auth: []ssh.AuthMethod{
				ssh.PublicKeys(signer),
			},
			HostKeyCallback: ssh.InsecureIgnoreHostKey(),
		}

		conn, err := ssh.Dial("tcp", address, config)
		if err == nil {
			conn.Close()
			break
		}

		time.Sleep(1 * time.Millisecond)
	}

	return time.Since(start), nil
}

func main() {
	vmName := flag.String("vm", "", "Name of the VM")
	sshAddress := flag.String("address", "", "SSH address in format host:port")
	sshUser := flag.String("user", "", "SSH user")
	sshKeyPath := flag.String("key", "", "Path to SSH key")

	flag.Parse()

	if *vmName == "" || *sshAddress == "" || *sshUser == "" || *sshKeyPath == "" {
		fmt.Println("Missing required flags")
		fmt.Println("USAGE:")
		fmt.Println("  ./main -vm vm-name -address 192.168.120.150:22 -user username -key ~/.ssh/id_rsa")
		return
	}

	fmt.Println("Starting VM...")
	if err := startVM(*vmName); err != nil {
		fmt.Printf("Failed to start VM: %v\n", err)
		return
	}

	fmt.Println("Waiting for SSH...")
	duration, err := waitForSSH(*sshAddress, *sshUser, *sshKeyPath)
	if err != nil {
		fmt.Printf("Error waiting for SSH: %v\n", err)
		return
	}

	fmt.Printf("SSH is ready after %v seconds\n", duration.Seconds())
}

OS	HOST	RAM	CPU	Time
Debian 12.9	AMD Ryzen 9 7950X, QEMU/KVM	8GB	4 cores	4.08s
Ubuntu 24.04	AMD Ryzen 9 7950X, QEMU/KVM	8GB	4 cores	4.58s
CentOS Stream 10	AMD Ryzen 9 7950X, QEMU/KVM	8GB	4 cores	7.20s