CODEWITHSUNDEEP
docker
markemus
markemus

Reputation: 1804

Adding --help for Docker image

Is there a way to add a --help message to a docker image that can be displayed when running from the command line? I haven't been able to find anything online or in the docker docs.

Upvotes: 0

Views: 90

Answers (1)

Adiii
Adiii

Reputation: 60074

You can add this in the entrypoint as mentioned by @Yazou, I am adding entrypoint in Dockerfile, you can create separate file as well.

This will log help message if container started with --help CMD otherwise it will start the desired process.

FROM alpine

RUN echo $'#!/bin/sh \n\ 
      echo "to see image helo run docker with --help" \n\
      if [ "${1}" == "--help" ]; then \n\
      echo "docker run -it --rm my_app argument1 argument1" \n\
      echo "my_app --option etc" \n\
      else \n\
      exec "$@" \n\
      fi \n\
     ' >> /bin/entrypoint.sh
RUN chmod +x /bin/entrypoint.sh

entrypoint ["entrypoint.sh"]

To test --help flag

docker run -it my_image --help

output

to see image helo run docker with --help
docker run -it --rm my_app argument1 argument1
my_app --option etc

without --help flag

docker run -it my_image

output

to see image helo run docker with --help

Upvotes: 1

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