How to copy multiple files in one layer using a Dockerfile?

Question

The following Dockerfile contains four COPY layers:

COPY README.md ./
COPY package.json ./
COPY gulpfile.js ./
COPY __BUILD_NUMBER          


        

Answer 1

simple

COPY README.md  package.json gulpfile.js __BUILD_NUMBER ./

from the doc

If multiple resources are specified, either directly or due to the use of a wildcard, then must be a directory, and it must end with a slash /.