defination
docker can build images automatically by reading the instructions from a dockerfile. dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.
usage
the docker build command builds an image from a dockerfile and context. the build‘s context is the set of files at a specified location PATH or URL. warning: don‘t use PATH /, because it can transfer the entire contents of your hard drive to the docker daemon.
docker build -f /home/vickey/dockerfile .
a. not case-sensitive but convention is UPPERCASE
原文：https://www.cnblogs.com/vickey-wu/p/8745953.html