Thank you. Of course, you can use a requirements.txt to install libraries. One benefit of Docker is, though, it caches preliminary images. Each command, like a RUN, creates a new preliminary image. When you change any command, Docker will use cached images until the point that changed and only rebuild the images from that point on. When you put everything in a single command, Docker will need to rebuild everything within this command, even if the change is minor, only.