COPY README.md package.json gulpfile.js __BUILD_NUMBER ./
or
COPY ["__BUILD_NUMBER", "README.md", "gulpfile", "another_file", "./"]
You can also use wildcard characters in the sourcefile specification. See the docs for a little more detail.
Directories are special! If you write
COPY dir1 dir2 ./
that actually works like
COPY dir1/* dir2/* ./
If you want to copy multiple directories (not their contents) under a destination directory in a single command, you’ll need to set up the build context so that your source directories are under a common parent and then COPY
that parent.