Unable to create Dockerfile from a Docker image due to permissions denied error

Question

I am trying to extract Dockerfile from Docker image.Taking look at a popular answer, I executed the following commands:

docker run -v /var/run/docker.sock:/var/run/docker.sock --rm alpine/dfimage -sV=1.36 quay.io/opendatahub/spark-cluster-image:spark24

Got the following error:

Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post "http://%2Fvar%2Frun%2Fdocker.sock/v1.36/images/create?fromImage=quay.io%2Fopendatahub%2Fspark-cluster-image&tag=spark24": dial unix /var/run/docker.sock: connect: permission denied

How do I get the corresponding Dockerfile for this image?

Where does that image come from? Looking at places like GitHub repositories for a Dockerfile might be a little more reliable than trying to reconstruct it from the built image. — David Maze, Nov 29 '20 at 13:11

score 1 · Accepted Answer · answered Nov 29 '20 at 11:14

1

Run with sudo command.

sudo docker run -v /var/run/docker.sock:/var/run/docker.sock --rm alpine/dfimage -sV=1.36 quay.io/opendatahub/spark-cluster-image:spark24

or add permissions

If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker your-user

answered Nov 29 '20 at 11:14

Shashank Sinha

492
2
7

Remember that it's very easy to root the host if you can run any `docker` command; consider the security implications before adding yourself to the `docker` group. – David Maze Nov 29 '20 at 13:09
What's the other way to execute docker ? If not `sudo` nor adding user to `docker` group. – Shashank Sinha Nov 29 '20 at 13:16
I'd prefer `sudo` on anything that's not a single-user developer machine. – David Maze Nov 29 '20 at 13:30
that's why I have suggested both ways of doing it. – Shashank Sinha Nov 29 '20 at 13:35

Unable to create Dockerfile from a Docker image due to permissions denied error

1 Answers1