How to Use AsyncSSH with asyncio for Asynchronous SSH (vs Paramiko Thread Executor)

AsyncSSH provides native support for handling SSH connections and commands asynchronously in Python with asyncio, offering a more efficient alternative to Paramiko’s thread-based executor approach. Unlike Paramiko, which is synchronous, AsyncSSH is built specifically for asynchronous operations, making it a better fit for asyncio tasks.

Getting Started with AsyncSSH

Installation

Before you start, install AsyncSSH using pip:

pip install asyncssh

Basic AsyncSSH Connection

Here’s a simple way to establish an SSH connection and execute a command using AsyncSSH:

import asyncio, asyncssh, sys

async def run_client():
    try:
        async with asyncssh.connect('hostname') as conn:
            result = await conn.run('ls', check=True)
            print(result.stdout, end='')
    except (OSError, asyncssh.Error) as exc:
        sys.exit('SSH connection failed: ' + str(exc))

asyncio.run(run_client())
    

Authentication Handling

Authentication can be handled by providing additional parameters during the connection setup:

async with asyncssh.connect('hostname', username='your_username', password='your_password') as conn:
    # Connection code here
    

Or using a private key:

async with asyncssh.connect('hostname', username='your_username', client_keys=['/path/to/private/key']) as conn:
    # Connection code here
    

Advanced Usage and Features

AsyncSSH isn’t just for executing commands; it supports a wide array of SSH-related tasks:

• Port forwarding
• Running an SSH server
• Handling multiple sessions
• File transfers using SFTP

Considerations When Using AsyncSSH

• Asynchronous Nature: Remember that all operations are non-blocking and should be handled within async functions.
• Error Handling: Properly handle exceptions and errors especially when dealing with network operations.
• Compatibility: Ensure that AsyncSSH is compatible with your server’s SSH implementation and version.

Why Not Paramiko with Asyncio?

While Paramiko can work with asyncio through run_in_executor for SSH operations, AsyncSSH with asyncio for asynchronous SSH connections delivers cleaner, more performant concurrent SSH handling without threading overhead.