Can I build a Docker container from Dockerfile in an interactive way with allocation of some pseudo TTY?

Question

I build container from below Dockerfile:

FROM ubuntu:14.04
...
RUN apt-get update && apt-get install -y vim
#RUN ssh-keygen -f /root/.ssh/id_rsa -N strongpass123$%^
RUN ssh-keygen -f /root/.ssh/id_rsa
...

I do it quite rarely, but there is many command before using of ssh-keygen and after it.

I know that I can do it from script through docker exec -it thirsty_darwin sh script.sh and then tag image and then use chaining of containers (images), but it is not as clear solution as I want.

Even worst case is with ssh-add ~/.ssh/id_rsa when I have to use expect tool. Expect tool has hardcoded my password. I do not want to do it.

Answer 1

Generally, you should not include any secrets in Docker images. See this answer for more on this topic.

Docker does not support interactive builds for good reasons as explained in this issue.

If you really need to do this, you can use docker commit like so:

docker build -t thirsty_darwin_base /path/to/Dockerfile
docker run -it --name=thirsty_darwin_changes thirsty_darwin_base /bin/bash
# do interactive stuff in the shell, then exit
docker commit thirsty_darwin_changes thirsty_darwin

Now thirsty_darwin has your interactive changes.

Update: Docker has released more comprehensive secrets management since this answer was written.