The Paranoid Guide to Running Copilot CLI in a Secure Docker Sandbox

[foreigner]

I recently started using Catnip (https://github.com/wandb/catnip) for this. Catnip also automatically manages multiple Git worktrees, and has a responsive UI for mobile.

[jaytaylor]

This is a really neat project .

At my company (StrongDM) we recently open-sourced a tool in this space called Leash: https://github.com/strongdm/leash

By default it runs in docker, and also includes an extra sophisticated macOS-native --darwin mode which goes beyond the capabilities and guarantees of the likes of sandbox-exe, bubblewrap, and in some ways docker. Leash provides visibility into and control over every command and network request attempted by the coder agent. Would appreciate any feedback, and will try to get in touch with the author (Gordon).

Now I'll definitely look into automatically supporting pass-through auth for at least gh cli in Leash - always looking for what folks will find useful.

[corv]

Interesting! The sandboxing space definitely deserves more attention.

On the other side of the spectrum, we're working on a lightweight approach that augments user namespaces with libseccomp to filter syscalls via BPF.

https://github.com/corv89/shannot

[udev4096]

Docker is not a sandbox, IT'S NOT! If you must, use gvisor or kata runtime for actual sandboxing

[NitpickLawyer]

Eh. While you're technically correct, there's a lot of nuance here. The threat model of running agents isn't one that needs "actual sandboxing". You're not looking to run malware that is purposefully designed to escape docker/podman. You're mainly looking to prevent the agent running silly rm-f's, or touch files outside its working env, or killing arbitrary processes, or mess up installed software. That's pretty much it. Some network control as well. ALl of these can be achieved with docker.

[pyuser583]

Could you expand on this?

[psidium]

I like this. I have crafted a Claude Code docker container to similar effects. My problem is that my env has intranet access all the time (and direct access to our staging environment) and I don’t want a coding agent that could go rogue having access to those systems. I did manage to spin up an iptables based firewall that blocks all requests unless they’re going to the IPs I allowlist on container start (I was inspired by the sandbox docs that Anthropic provides). My problem right now is that some things that my company use are behind Akamai, so a dig lookup + iptables allow does not work. I’ll probably have to figure out some sort of sidecar proxy that would allow requests on the fly instead of dig+iptables.

[BimJeam]

I use incus for these type of things. Comes with advantages as passing through gpu as well.

[codazoda]

I built a similar container when working on a CTF that didn’t exclude the use of AI tools.

https://github.com/codazoda/llm-jail