TIPS on building from a Dockerfile

The directory the Dockerfile finds itself in is important!

The docker build command builds a Docker image from a Dockerfile and a “context”. A build’s context is the set of files located in the specified PATH or URL.
For example, if you use the command `docker build .` the context is the current directory `.` and its subdirectories.
The build process can refer to any of the files in the context, so build will take a LONG time (and the Docker image will get bigger and bigger) if your Dockerfile is in your home directory!

If you download a Dockerfile from an online repository like github, it will often have a project directory that accompanies it. Build that Dockerfile in its project directory: that is the context it needs!
If the Dockerfile is stand-alone (does not have a project directory), put the Dockerfile in its own empty directory before you run docker build .
If you would like to give your Docker image a name, use the -t flag to tag it: docker build -t mycow .

Docker 4 (5 pts): build