Docker in Docker | Github actions - Self Hosted Runner - docker

Question

Am trying to create a self-hosted runner for Github actions on Kubernetes. As a first step was trying with the docker file as below:
FROM ubuntu:18.04
# set the github runner version
ARG RUNNER_VERSION="2.283.1"
# update the base packages and add a non-sudo user
RUN apt-get update -y && apt-get upgrade -y && useradd -m docker
RUN useradd -r -g docker nonroot
# install python and the packages the your code depends on along with jq so we can parse JSON
# add additional packages as necessary
RUN apt-get install -y curl jq build-essential libssl-dev apt-transport-https ca-certificates curl software-properties-common
# install docker
RUN curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add - \
&& add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable" \
&& apt update \
&& apt-cache policy docker-ce \
&& apt install docker-ce -y
ENV TINI_VERSION v0.19.0
ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
RUN chmod +x /tini
RUN usermod -aG docker nonroot
USER nonroot
# set the entrypoint to the start.sh script
ENTRYPOINT ["/tini", "--"]
CMD ["/bin/bash"]
After doing a build, I run the container with the below command:
docker run -v /var/run/docker.sock:/var/run/docker.sock -it srunner
When i try to pull image, I get the below error:
nonroot#0be0cdccb29b:/$ docker run hello-world
docker: Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post "http://%2Fvar%2Frun%2Fdocker.sock/v1.24/containers/create": dial unix /var/run/docker.sock: connect: permission denied.
See 'docker run --help'.
nonroot#0be0cdccb29b:/$
Please advise if there is a possible way to run docker as non-root inside a docker container.

Answer 1

Instead of using sockets, there is also a way to connect to outer docker, from docker in container, over TCP.
Linux example:
Run ifconfig, it will print the docker's network interface that is created when you install docker on a host node. Its usually named docker0, note down the IP address of this interface.
Now, modify the /etc/docker/daemon.json and add thistcp://IP:2375 to the hosts section. Restart docker service.
Run containers with extra option: --add-host=host.docker.internal:host-gateway
Inside any such container, the address tcp://host.docker.internal:2375 now points to the outside docker engine.

Answer 2

Try adding your username to the docker group as suggested here.
Additionally, you should check your kernel compatibility.