Interactive command in Dockerfile

Question

I'm trying to automate a creation of a development Docker image using docker build command with appropriate Dockerfile. One of the scripts that I need to run in a RUN command wants the user to click through and read their license agreement. Thus there are two questions:

1. Where is the output of all the RUN commands in a Dockerfile?
2. What solution is possible to interact with the aforementioned command? Right now the docker build command just gets stuck asking user for input in an infinite loop.

Answer 1

You can use the technique here:

(echo "initial command" && cat) | some_tool

Or, if multiple stages use printf and concat with \n:

(printf "cmd1\ncmd2" && cat) | some_tool

Answer 2

The output of RUN commands is shown in your terminal during the build. The Docker build process is completely non-interactive, so you must find some way of either auto-accepting the terms (almost every piece of software allows this, think apt-get install -y...) or using some shell wizardry to echo the acceptance back to the process or whatever (Expect maybe?).

Answer 3

You can also do it in several steps, begin with a Dockerfile with instructions until before the interactive part. Then

docker build -t image1 .

Now just

docker run -it --name image2 image1 /bin/bash

you have a shell inside, you can do your interactive commands, then do something like

docker commit image2 myuser/myimage:2.1

The doc for docker commit

https://docs.docker.com/engine/reference/commandline/commit/

you may need to specify a new CMD or ENTRYPOINT, as stated in the doc

Commit a container with new CMD and EXPOSE instructions

For example some docker images using wine do it in several steps, install wine, then launch and configure the software launched in wine, then docker commit