SSH ForwardAgent does not work for openvscode

[nrontsis]

What happened?
ForwardAgent does not work on openvscode. If I do e.g.

devpod up https://github.com/loft-sh/devpod-example-go --provider docker --ide openvscode

the ssh_auth_sock is pointing to a non-existing file.

vscode ➜ /workspaces/devpod-example-go (main) $ ssh -T [email protected]
[email protected]: Permission denied (publickey).
vscode ➜ /workspaces/devpod-example-go (main) $ ls $SSH_AUTH_SOCK
ls: cannot access '/tmp/auth-agent3979699691/listener.sock': No such file or directory

while manually ssh'ing into the pod via ssh devpod-example-go.devpod has no issue: i.e. ForwardAgent works fine, and I can authenticate e.g. in github fine.

What did you expect to happen instead?
ForwardAgent to work for openvscode, as it does when I ssh into the pod.

How can we reproduce the bug? (as minimally and precisely as possible)
Run:

devpod up https://github.com/loft-sh/devpod-example-go --provider docker --ide openvscode

Local Environment:

• DevPod Version: v0.5.21
• Operating System: linux + mac
• ARCH of the OS: AMD64 + ARM64

DevPod Provider:

• Local/remote provider: docker 20.10.21

Anything else we need to know?
Nothing

[bkneis]

@nrontsis thanks for raising this issue and providing a clear summary and example! I have replicated the issue and can confirm the problematic behaviours. After debugging I believe the issue is here https://github.com/loft-sh/devpod/blob/main/pkg/ssh/server/ssh.go#L136. We are overriding the SSH_AUTH_SOCK env var on each handler in the SSH server. I believe the issue is caused due to additional SSH commands that are sent in order to set up the container tunnel via the browser. For instance if you perform ls -la /tmp/auth-agent* you can see the correct listener.sock just in the wrong temp directory. If you manually update SSH_AUTH_SOCK to point to this file it works again.

I think the fix is to change the SSH server implementation so we can specify on a per connection basis if the SSH_AUTH_SOCK should be updated. This might be a fairly big change and I am currently occupied with another feature but will return to this soon!

[nrontsis]

thanks a lot for the reply and the analysis @bkneis!