How to SSH agent forward into a docker container

docker-ssh-forward.bash

docker run -rm -t -i -v $(dirname $SSH_AUTH_SOCK) -e SSH_AUTH_SOCK=$SSH_AUTH_SOCK ubuntu /bin/bash

@Sylvain, give a chance to WSL (Windows Subsystem for Linux).

@kynan if you aren't using a remote user database for your system (eg LDAP/AD) you can map in /etc/passwd read-only so SSH can find your user.

Maybe, there is similar way to integrate gpg into docker container?

@ghost asks

Maybe, there is similar way to integrate gpg into docker container?

Browsing around, I saw this: https://github.com/transifex/docker-gpg-agent-forward

How if docker-compose and docker-daemon not in a same machine such as boot2docker?
I want to put this bunch of parameters in the docker-compose.yaml instead of typing them every time.

For anyone who comes across this: This will not work for anyone using Docker for Mac due to os limitations around file socket access. See: docker/for-mac#410

This works for me for the first shell logon, but fails for successive attempts. My use case is a remote container that has a longer lifespan, usually of a couple weeks. Is there a solution that is robust against the changing of the SSH_AUTH_SOCK target?

docker run -dit \
	--network host \
	--gpus all \
	--restart unless-stopped \
	--privileged \
	-e "DISPLAY=$DISPLAY" \
	-e "QT_X11_NO_MITSHM=1" \
        -e "$SSH_AUTH_SOCK:/ssh-agent" \
        -e "SSH_AUTH_SOCK=/ssh-agent" \
	-v "$XSOCK:$XSOCK" \
	-v "$HOME/data:/root/data:rw" \
	-v "$HOME/.gitconfig:/root/.gitconfig" \
	--name $NAME $NAME:latest bash

The official guidance works for me, when nothing else has. It's not very well explained, but the bind mount paths are magic values to allow SSH agent forwarding.

-e "$SSH_AUTH_SOCK:/ssh-agent" \

maybe -v here instead of -e ?

Hi everyone. I have the same problem. Has anyone found the solution?
This works for me for the first shell login, but fails for successive attempts

sudo docker run --restart always --network host --name github-runner -v $SSH_AUTH_SOCK:/ssh-agent -e SSH_AUTH_SOCK=/ssh-agent -e REPO_URL="$REPO_NAME" -e ACCESS_TOKEN="$ACCESS_TOKEN" myoung34/github-runner:latest

If you're on a mac, the current incantation should be:

docker run -it --rm -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock -e SSH_AUTH_SOCK="/run/host-services/ssh-auth.sock" debian bash

For anyone struggling to get ssh-agent forwarding to work for non-root container users, here's the workaround I came up with, running my entry point script as root, but using socat + su-exec to expose the socket to the non-root user and then run commands as that user:

1. Add socat and su-exec to the container in your Dockerfile (you might not need the later if you're not using alpine)

USER root
RUN apk add socat su-exec
# for my use case I need www-data to have access to SSH, so 
RUN \
    mkdir -p /home/www-data/.ssh && \
    chown www-data:www-data /home/www-data/.ssh/

2. In your entrypoint:

#!/bin/sh
# Map docker's "magic" socket to one owned by www-data
socat UNIX-LISTEN:/home/www-data/.ssh/socket,fork,user=www-data,group=www-data,mode=777 \
    UNIX-CONNECT:/run/host-services/ssh-auth.sock \
    &
# set SSH_AUTH_SOCK to the new value
export SSH_AUTH_SOCK=/home/www-data/.ssh/socket
# exec commands as www-data via su-exec
su-exec www-data ssh-add -l
# SSH agent works for the www-data user, in reality you probably have something like su-exec www-data "$@" here

3. Run your container as @conf states:

docker run -it --rm -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock -e SSH_AUTH_SOCK="/run/host-services/ssh-auth.sock" name cmd

shrug this: -v "$SSH_AUTH_SOCK:$SSH_AUTH_SOCK" -e SSH_AUTH_SOCK=$SSH_AUTH_SOCK worked for me. The original gist did not.

@unphased Probably due to the symlink situation, as @arunthampi noticed here.

The line the worked for me was docker run -i -t -v $(readlink -f $SSH_AUTH_SOCK):/ssh-agent -e SSH_AUTH_SOCK=/ssh-agent ubuntu /bin/bash

@unphased
volume $SSH_AUTH_SOCK:/ssh-agent
and ENV SSH_AUTH_SOCK=/ssh-agent worked for me for years.
But after I've upgraded packages to the latest (ubuntu 22), the agent just stopped working! I mean - ssh-add -l was saying that it does not have access to the agent.
Thank you, your snippet works! Spent the whole day on this issue ))

Check if you use docker from snap. In my Kubuntu 22.04 I remove docker from snap and install using apt and problem is fixed

the latest official documentation helped me with docker-compose setup
https://docs.docker.com/desktop/networking/#ssh-agent-forwarding

is there a version of setup for Redhat linux and distributions based on it like CentOS and Rocky?

the latest official documentation helped me with docker-compose setup https://docs.docker.com/desktop/networking/#ssh-agent-forwarding

That seems to be specific to Docker Desktop. What about Colima and/or Podman?

Based on @tomdavies post, i created this Dockerfile which uses the USER statement in order to have an unpriviledged container instead of su-exec:

FROM python:3.11.6-alpine

RUN apk --no-cache add --update \
    socat \
    sudo

RUN addgroup --gid 1001 -S ansible && adduser --uid 1001 -S ansible -G ansible -h /home/ansible
RUN echo 'ansible ALL=(ALL:ALL) NOPASSWD:/usr/local/bin/create-ansible-agent-socket.sh' > /etc/sudoers
RUN echo 'socat UNIX-LISTEN:/home/ansible/.ssh/agent,fork,user=ansible,group=ansible,mode=777 UNIX-CONNECT:/root/.ssh/agent' > /usr/local/bin/create-ansible-agent-socket.sh
RUN chmod +x /usr/local/bin/create-ansible-agent-socket.sh
RUN echo 'sudo /usr/local/bin/create-ansible-agent-socket.sh & SSH_AUTH_SOCK=/home/ansible/.ssh/agent "$@"' > /entrypoint.sh

USER ansible
RUN mkdir -p /home/ansible/.ssh && chown ansible:ansible /home/ansible/.ssh

ENTRYPOINT [/bin/sh, /entrypoint.sh]

you run it then with

docker run -it -u ansible \
    -v "$SSH_AUTH_SOCK":/root/.ssh/agent \
    -e SSH_AUTH_SOCK=/root/.ssh/agent \
    name cmd

@benjertho After struggling for hours with the same problem (works on first shell login but after that fails), I tried a hack and it worked! Sharing here:

• Add an entrypoint line to dockerfile
  ENTRYPOINT ["/ros_entrypoint.sh"]

• In entrypoint script, add the following at the top:

# Dynamically set SSH_AUTH_SOCK if it's available in the mounted /tmp directory
if [ -n "$(find /tmp -type s -name 'agent.*' 2>/dev/null)" ]; then
  export SSH_AUTH_SOCK=$(find /tmp -type s -name 'agent.*' 2>/dev/null)
fi

• Add the following to your compose.yaml:

environment:
    - SSH_AUTH_SOCK=/tmp/ssh-agent
volumes:
    - /tmp:/tmp

Now the ssh auth sock will be set appropriately every time.

run docker -p  222:22 && apt install openssh-server &&  $(edit /etc/ssh/sshdconfig to enable root login)

on your mac of git bash

eval $(ssh-agent -s)
ssh-add 
ssh -A  toDockerContainer

Thanks! You pointed me in the right direction for a very similar problem. Here’s my take on it, implemented within a Makefile. This is very much specific to a mac os problem with a Docker Desktop solution.

# izumanetworks.com ai-edge-runner
run:
    @if [ -z "$(WORKSPACE_PATH)" ]; then \
        echo "Error: Please specify the path to map using MAP=/path/to/map"; \
        exit 1; \
    fi
    @if [ -z "$(SSH_AUTH_SOCK)" ]; then \
        echo "Error: SSH agent is not running. Please start it with 'eval $$(ssh-agent -s)' and add your key with 'ssh-add'."; \
        exit 1; \
    fi
    docker run -it \
        --name $(CONTAINER_NAME) \
        -e SSH_AUTH_SOCK=/run/host-services/ssh-auth.sock \
        -v /run/host-services/ssh-auth.sock:/run/host-services/ssh-auth.sock \
        -v $(WORKSPACE_PATH):/izuma \
        --entrypoint /bin/bash \
        $(IMAGE_NAME)

The magic is that even though macOS doesn’t have a /run/blah/blah path, Docker Desktop creates /run/host-services/ssh-auth.sock as a special bridge to your host system’s SSH_AUTH_SOCK.

To test, run ssh-add -l inside the container to list your keys and ssh -T git@github.com to verify connectivity. This approach works seamlessly with Docker Desktop on macOS.

the latest official documentation helped me with docker-compose setup https://docs.docker.com/desktop/networking/#ssh-agent-forwarding

That seems to be specific to Docker Desktop. What about Colima and/or Podman?

Did you ever figure this out on Podman specifically?