Share SSH keys with VS Code Devcontainer running with Docker's WSL2 backend - visual-studio-code

Question

I'm reading these docs on sharing SSH keys with a dev container, but I can't get it to work.
My setup is as follows:
Windows 10 with Docker Desktop 4.2.0 using the WSL2 backend
A WSL2 distro running Ubuntu 20.04
In WSL2, I have ssh-agent running and aware of my key:
λ ssh-add -l
4096 SHA256:wDqVYQshQBCG/Sri/bsgjEaUFboQDUO/9FJqhFMncdk /home/taschan/.ssh/id_rsa (RSA)
The docs say
the extension will automatically forward your local SSH agent if one is running
But if I do ssh-add -l in the devcontainer, it responds with Could not open a connection to your authentication agent.; and of course starting one (with eval "$(ssh-agent -s)") only starts one that doesn't know of my private key.
What am I missing?

Answer 1

I had basically the same issue. Running Windows 11 with WSL2 and my VSCode Devcontainer wouldn't show any ssh keys (running ssh-add -l inside the container showed an empty list) despite having Git configured on my host machine with working ssh keys.
For me, there were 3 separate instances of ssh-agent on my machine:
WSL2
Git Bash
Windows host 🠆 This is the one VSCode is forwarding to the devcontainer
My existing ssh keys were set up inside Git Bash (as per Github's instructions) so running ssh-add -l only ever showed my ssh keys from inside a Git Bash terminal, nowhere else.
However, as explained in the previous answer, digging through the Devcontainer startup logs shows that VSCode is forwarding only the host machine's ssh-agent, it doesn't look at the WSL2 or Git Bash ones.
Solution: I suggest following the below Microsoft docs page. You need to enable an "Optional Feature" in Windows, then run a few commands in PowerShell (as admin) to activate the ssh-agent service. With this set up, the ssh-agent/ssh-add commands will work from a regular CMD terminal too.
You can use these with the usual keygen commands etc to generate and add new keys on the host (I just ssh-add'ed the same keys generated by Git Bash originally). The added keys should immediately be detected by ssh-add -l inside the container.
https://learn.microsoft.com/en-us/windows-server/administration/openssh/openssh_keymanagement

Answer 2

I tried many things but did not work. Finally after devcontainer is created , I note down the container name and copy the id_rsa and id_rsa.pub key inside container using docker cp command.
syntax:
docker cp <sourcefile> container_id:/dir
Copy both private and public key:
docker cp /root/.ssh/id_ed25519 eloquent_ritchie:/root/.ssh/
docker cp /root/.ssh/id_ed25519.pub eloquent_ritchie:/root/.ssh/
change the permission of private key so that you can do git operations
docker exec eloquent_ritchie chmod 600 /root/.ssh/id_ed25519
eloquent_ritchie is sample container name. Your container name will differ. Use your container name
Then I was able to do Git operations inside devcontainer.
If you rebuild your container again you need to copy the file to devcontainer again.

Answer 3

I also had quite a lot of trouble to get this to work. The following steps might help troubleshooting:
Check that ssh-agent is running on your host and the key is added
Run ssh-agent -l on Windows and expect to see the name of your key
Check that VSCode forwards the socket
Search ssh-agent in the startup log. I had the message
ssh-agent: SSH_AUTH_SOCK in container (/tmp/vscode-ssh-auth-a56c4b60c939c778f2998dee2a6bbe12285db2ad.sock) forwarded to local host (\\.\pipe\openssh-ssh-agent).
So it seems that VSCode is directly forwarding the Windows SSH agent here (and not an SSH agent running in your WSL).