Docker - how can I copy a file from an image to a host?

Question

My question is related to this question on copying files from containers to hosts; I have a Dockerfile that fetches dependencies, compiles a build artifact from source, and

Answer 1

docker cp $(docker create --rm registry.example.com/ansible-base:latest):/home/ansible/.ssh/id_rsa ./hacked_ssh_key

wanted to supply a one line solution based on pure docker functionality (no bash needed)

edit: container does not even has to be run in this solution

edit2: thanks to @Jonathan Dumaine for --rm so the container will be removed after, i just never tried, because it sounded illogical to copy something from somewhere which has been already removed by the previous command, but i tried it and it works

Answer 2

You could bind a local path on the host to a path on the container, and then cp the desired file(s) to that path at the end of your script.

$ docker run -d \
  -it \
  --name devtest \
  --mount type=bind,source="$(pwd)"/target,target=/app \
  nginx:latest

Then there is no need to copy afterwards.