We have a Dockerfile, where at a certain point would like no caching to happen.

Currently we are using

`ENV CACHE_BUST=$($RANDOM)` 

Upon further inspection, funny enough that gets cached:

`Step 1/1 : ENV CACHE_BUST=$($RANDOM)
---> Using cache`

Is there any way from inside the Dockerfile to bust the cache **without passing in a unique `build-arg`** (Like `docker build . --build-arg CACHE_BUST=$(date +%s)`) in the build step?