Ability to "sysprep" containers
It would be great to have a mechanism for performing some actions when a container is first created.
One example is devops scenario where a container image is prepared, then when a new container is created from that image and started, it downloads and installs the latest version of the app.
Justin Higgins commented
Containers are ephemeral. Containers should also be immutable. Therefore you would not want anything changing at RUN time. However, Docker provides a mechanism for this at BUILD time called multi-stage containers.
If this doesn't achieve what you are trying to do, please explain.