func GetConfigPEM(user, keyFile string) (*ssh.ClientConfig, error) {
	key, err := ioutil.ReadFile(keyFile)
	if err != nil {
		return nil, fmt.Errorf("unable to read private key: %v", err)
	}
	signer, err := ssh.ParsePrivateKey(key)
	if err != nil {
		return nil, fmt.Errorf("unable to parse private key: %v", err)
	}
	return getConfig(user, ssh.PublicKeys(signer)), nil
}
GetConfigPEM returns SSH configuration that uses the given private key.
the keyfile should be unencrypted PEM-encoded private key file.
package vssh
import (
	"fmt"
	"io/ioutil"
	"golang.org/x/crypto/ssh"
)