Behaviour of RUN command in Dockerfile

RUN command in dockerfile utilises cache when the command is found same, but it is not necessarily true that state of image will be same after executing same command especially when we are dependent on external system.


RUN wget -O xyz.txt

The file we are trying to download can change time to time but the docker engine will consider that the command is unchanged which is not aligned with the state of image generated after the command is executed.

Did community had discussion on this topic in past? Or is this intentional?