SSH Agent forwarding inside docker compose container

Question

Could not open a connection to your authentication agent.

I am following the approach of mounting the $SSH_AUTH_SOCK as a volume, but doing so with compose.

Answer 1

I solved it using whilp/ssh-agent, though you should note that this is not using SSH_AUTH_SOCK directly and requires an additional long running container. I'll integrate this approach into docker-rails for ease of use.

1. Start a long running container docker run -d --name=ssh-agent whilp/ssh-agent:latest

2. Add your key docker run --rm --volumes-from=ssh-agent -v ~/.ssh:/ssh -it whilp/ssh-agent:latest ssh-add /ssh/id_rsa

3. List your keys docker run --rm --volumes-from=ssh-agent -v ~/.ssh:/ssh -it whilp/ssh-agent:latest ssh-add -L

4. bash into a container and check the key with ssh -T git@bitbucket.org

My yaml looks like:

web:
    build: .
    working_dir: /project
    ports:
      - "3000"

    environment:
      # make ssh keys available via ssh forwarding (see volume entry)
      - SSH_AUTH_SOCK=/ssh-agent/socket

    volumes_from:
      # Use configured whilp/ssh-agent long running container for keys
      - ssh-agent

Answer 2

The previous accepted answer using whilp/ssh-agent did not work for me for some reason (it worked before but since last changes it doesn't and I don't know why) so I created my own agent container:

docker-ssh-agent

based on minimal alpine:3.4 base image. So anyone still having trouble with this on OSX, check the README it's now really easy to get it up and running!