1. What is Dockerfile?
Not only can we pull image files from Docker hub, we can also use Dockerfile to help us build a custom image.
Dockerfile becomes the image build file description file
2. Why there is a Dockerfile
problem: Many mirrors are officially provided in docker hub to satisfy all our services. Why do we need to customize mirrors?
Core role: In the future, users can package their applications into images, so that our applications can be run in containers.
3. Dockerfile build mirror principle
4. Dockerfile use
