SSH access to sandbox pods

[nthh]

Summary

Let users SSH into their sandbox from a local terminal, enabling use of local editors and tools.

User stories

• "I want to use my local VS Code / Neovim connected to the sandbox via SSH"
• "I want to scp files in/out of my sandbox"
• "I want to use my local terminal instead of the browser"

Approaches (pick one)

1. kubectl exec proxy (simplest)

• Add an API endpoint that proxies SSH-like access through the server
• Users connect via a CLI tool or ssh with ProxyCommand
• No changes to container image needed
• Leverages existing K8s exec infrastructure

2. SSH bastion on server pod

• Run sshd on the remolt server pod
• ssh {session-id}@remolt.dev → server does kubectl exec into the sandbox
• Clean UX, single entry point
• Need to manage SSH key injection (from GitHub profile or upload)

3. Tailscale/WireGuard sidecar

• Add Tailscale sidecar to sandbox pods
• Users join the same tailnet and SSH directly
• Most polished, supports VS Code Remote SSH natively
• Most complex to set up

4. Direct sshd in pods

• Install sshd in container, expose via NodePort/LoadBalancer
• Inject user's SSH key during pod creation (fetch from GitHub API)
• Simple but hard to manage ports at scale

Considerations

• Network policy currently blocks all pod ingress except from server pod
• Auth: SSH keys from GitHub profile (https://github.com/{user}.keys) would be seamless
• VS Code Remote SSH compatibility is a big draw
• Security: sandboxes already have sudo, SSH doesn't change the threat model