String_SSH.kt

import net.schmizz.sshj.SSHClient

fun String.on(host: String? = "localhost", user: String = "root", retry: Int = 3): String {
    val ssh: SSHClient = SSHClient();
    ssh.addHostKeyVerifier { a, b, c -> true };
    for ( i in 1..retry) {
        try {
            ssh.connect(host);
            return ssh use {
                ssh.authPublickey(user);
                ssh.startSession()?.use {
                    session ->
                    session.exec(this)?.getInputStream()?.use {
                        ins ->
                        String(ins.readBytes(2048))
                    }
                }?:throw Exception("Could not start session on $host")
            }
        } catch (e: Exception) {
            if ( i < retry ) {
                println("Retrying for the $i time to ssh $user@$host -c $this  (${e.getMessage()})")
                Thread.sleep(100)
            } else {
                throw e
            }
        }
    }
    throw Exception("Failed to execute '$this' on $host as $user after $retry attempts")
}