How to install docker in docker container?

I had a similar problem trying to install Docker inside a Bamboo Server image. To solve this:

1. first remove the line: RUN docker run hello-world from your Dockerfile
2. The simplest way is to just expose the Docker socket, by bind-mounting it with the -v flag or mounting a volume using Docker Compose:

docker run -v /var/run/docker.sock:/var/run/docker.sock ...