Show HN: Sshsync – CLI tool to run shell commands across multiple remote servers

In a past life, this is an interview question that I would ask people: "We have thousands of servers, and you need to run the same command on 10 of them, what's one way you would do it?" and follow up with "What if you wanted to run the command on hundreds or thousands - what problems would you expect with this approach, and what might you do differently?"

I didn't really expect them to write code on the spot (hate that in interviews), but just to describe a possible solution; there were no wrong answers. Seeing how people came up with a quick hack for 10 and then being able to evolve their thinking for thousands was the point of the question and it could be enlightening to see.

I had a lot of people come up with things that I never even thought of, such as SSH'ing in to all 10 machines and then using a terminal feature to type into all of the windows at once.

Around 10 years ago I was supporting infrastructure at a PHP shop and we needed a similar thing, but for ~3000 servers, and the library that we were using (libpssh) didn't support async SSH agent authentication, so I built this small tool in Go to allow to implement such tooling in any language (PHP, Python, whatever) in a simple way: https://github.com/YuriyNasretdinov/GoSSHa

It's main advantage is that it allows you to do SSH agent forwarding that actually works at scale, since it limits concurrency when talking to SSH agent to a configurable amount (by default 128, the default connection backlog in OpenSSH ssh-agent)

Very cool project! But it's a quite saturated market. Any sysadmin/similar who needs this sort of functionality have most likely already found an solution (5-20 years ago).

Personally, I'm a tmux synchronized-panes kind of guy, so that I can see the result of each output immediately.

Looks interesting; my klunky script for doing something similar has been something along the lines of

    printf 'started: %s\n' "$(utcdate)"

    (
        trap 'kill 0' SIGINT
        for REMOTE in "${REMOTES[@]}"
        do
            ssh -- "$REMOTE" "$COMMAND" "$@" &
        done
        wait
    )

    printf 'ended: %s\n' "$(utcdate)"

but twiddling with it has been quite annoying, so I'll look into this tool.

ansible my_servers -m shell -a 'fortune && reboot' -b

I know it is easy to be a hater, but sincerely do not see a reason to use something like that over Ansible or just pure sh, ssh and scp. All you have to do is to set up keys and the inventory. Takes 10 minutes, even if you are doing it for the first time. And you can expand it if you need it.

How are commands handled, that require user input? E.g. password for sudo in your example:

  sshsync group web-servers "sudo systemctl restart nginx"

I like that you included a demo in the README, but it is too long for a gif, as I can't pause/rewind/forward. So splitting into multiple short gifs or converting into a video (if GitHub supports them) could improve the experience.

Have you looked at what powershell does? Invoke-Command (and the Job stuff it meshes perfectly with via AsJob) is really nice

I only needed a very small fraction of what it can do to bail a client out of a problem their customer caused on several hundred computers the night before an event, but it absolutely saved the day and a lot of money.

Curious to understand the need to create this over using tools like pssh, etc.

https://linux.die.net/man/1/pssh

I built (and still use) a similar tool called Overcast 10 years ago: https://github.com/andrewchilds/overcast

To me GNU parallel is the top of the line here (as it is for most things parallel).

For the most common cases I have it aliased to just `p`: https://github.com/Julian/dotfiles/blob/main/.config/zsh/com...

Or https://github.com/Julian/dotfiles/blob/4d36e6b17e9804a887ba...

The dry-run option is nice, but you can do this easily in a normal environment without special tooling (GNU parallel, etc).

I have made scripts to do this with filter parameters over VMs on cloud providers, which is very valuable. Maybe you can extend this to have those options, so potential users are more attracted to it?

This looks great. I've used ansible in the past, is this tool like a stripped down (and thus simpler to use) version of ansible?

See also: fabric. https://docs.fabfile.org/en/latest/

If you deploy with Kamal you practically get this, except maybe the file push, that's a nice touch.

This would only be interesting if it wasn't written in python, but native instead.

The lack of research, the AI-generated README and comments, and the "Pythonic" approach (while Ansible exists) made me laugh. I guess it's a good CS50 project, but it's not presentable at all and doesn't have real-world usage.