To reduce image layers its common for docker images to combine multiple commands in a single RUN. eg. https://github.com/docker-library/redis/blob/9db6cc1645465f134d03584dbbbd962ce822479a/3.2/alpine/Dockerfile .
It’s also common to CURL or WGET a zip file from an external location.
I would like to add a zip file from within a RUN command in the same way the COPY command works.
To explain further, I have a large local zip file and I don’t want to use COPY because that adds a new layer, increasing my image size. I want to do whatever COPY does but from within a RUN command. I can then chain my commands together resulting in 1 layer rather than 2.
What does COPY actually do?