ssh_connection.py

import paramiko
from scp import SCPClient
from io import StringIO
import os


def start_deployment(ip, files, commands, key_material):
    """
    This function starts the deployement process for the instance with the provided ip address.
    The deployement script is runned on the instance. The provided deployement commands are also 
    runned on the instance before closing the connection.
    """
    try:
        connection = instance_connection(ip, key_material)
        transfer_file(connection, files)
        run_commands(connection, commands)
        connection.close()
    except Exception as e:
        print(e)
    finally:
        exit(None)


def instance_connection(instance_ip, key_material):
    """
    This function initialize a connection with the ec2 instance.
    """
    ssh_username = "ubuntu"
    ssh_key_file = StringIO(key_material)
    rsa_key = paramiko.RSAKey.from_private_key(ssh_key_file)

    ssh_connection = paramiko.SSHClient()
    ssh_connection.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh_connection.connect(hostname=instance_ip, username=ssh_username,
                           pkey=rsa_key, allow_agent=False, look_for_keys=False)
    print("connection success")
    return ssh_connection


def transfer_file(ssh_connection, files):
    """
    Initializes a SCP connection using a SSH connection and transfer the file to the instance connected
    to the session.
    :param ssh_connection: SSH connection established with the instance
    :param files: The files to trnasfer
    """
    scp_connection = SCPClient(ssh_connection.get_transport())
    for file in files:
        scp_connection.put(file, remote_path='/home/ubuntu')


def get_file_from_remote(ssh_connection, filename):
    """
    Gets a file from a remote instance
    :param ssh_connection: The ssh connection established with the instance
    :param filename: The name of the file to fetch from the instance
    """
    ftp_client = ssh_connection.open_sftp()
    ftp_client.get("/home/ubuntu/{}".format(filename), os.path.join(os.path.curdir, filename))


def run_commands(ssh_connection, commands):
    """
    Executes a list of bash commands in the instance connected to the SSH session.
    """
    for command in commands:
        print("running command: {}".format(command))
        _, stdout, stderr = ssh_connection.exec_command(command)
        print(stdout.read())
        print(stderr.read())


def close_connection(ssh_connection):
    ssh_connection.close


if __name__ == "__main__":
    connection = instance_connection("18.232.164.184")
    run_commands(connection, ["mkdir folder", "cd folder", "ls"])
    connection.close()