Running multiple SSH client sessions using russh

help
1

Hello,

I wonder if anybody has experience in using russh.

I successfully run the client example. Now I'm trying to figure out how to run multiple programs at the same time which I think should be possible.

There are 3 stages:

Session::connect()                       // connect over SSH
session.session.channel_open_session()   // returns handle to a session channel
channel.exec()                           // executes a program

I tried to clone session and channel and none of them are clonable which means I can't tokio::task::spawn it to execute multiple programs. The only thing I can spawn is the whole thing (including Session::connect()) which is like typing ssh user@host several times and I'd quickly hit limits if I tried that...

Thank you.

2

I don't have any experience with russh, but from a quick glance at Handle::open_session, it looks to me like opening a new session is a light-weight operation, suitable for running multiple sessions through the same Handle. You could share the Handle with an Arc between tasks, or create a new channel and pass that to your task by value.

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3

Thank you @jofas

Unfortunately session (created by Session::connect()) and channel (created by session.channel_open_session()) must be mutable. I can put it into Arc and Mutex but then the Mutex will need to stay locked for the whole duration of a spawned thread...

4

Okay so what about my second proposal,

where you create a new channel for each task you spawn via Handle::open_session? When you pass a channel by value to a task, the task takes ownership of that channel. This allows the task to mutate the channel independently from any other channel some other task might be mutating simultaneously.

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5

That works! Thank you @jofas :kissing_heart:

For anybody reading this, if you need an explanation like you're 5 (which is what I need :wink: ):

Outside a for loop connect to a server:

let mut session = Session::connect(...

Then inside a for loop:

let mut channel = session.open().await;
let handle = tokio::task::spawn(async move {
  Session::call(&mut channel...
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6

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