omniwarn

Tool for making all executables in a Docker image print a warning when run.

Meant to be used for deprecation warnings on no longer maintained images.

Installation

Everything is contained in a single script, so just download that into the directory with your Dockerfile and make it executable:

curl -L "https://raw.githubusercontent.com/smheidrich/omniwarn/main/omniwarn" -o omniwarn
chmod +x omniwarn

Usage

Help text:

$ ./omniwarn -h
Usage: omniwarn <command> [arguments...]

Extreme hackjob to make a Docker image print warnings with (almost) any use.

Meant for deprecation warnings in images that are so old nobody should be using
them anymore but are getting downloads anyway. DON'T USE on images that are
actually important.

Works by replacing almost every single executable in the image with a wrapper
that prints a warning, then executes the original executable.

Example usage in Dockerfile, after writing your desired warning message into a
file named "warning":

  COPY omniwarn warning ./
  RUN ./omniwarn replace-all

Putting this at the end of your Dockerfile will build an image that prints your
warning message to stderr the first time any program is launched.


Commands:

replace-all - Replace (almost) all executables on the system
revert-all  - Undo all replacements

License

Unlicense (basically equivalent to public domain plus no-warranty disclaimer) so you can add the script to repositories containing deprecated Dockerfiles without having to worry about including anything else. See LICENSE.md.