Docker how to ADD a file without committing it to an image?

According to the documentation, if you pass an archive file from the local filesystem (not a URL) to ADD in the Dockerfile (with a destination path, not a path + filename), it will uncompress the file into the directory given.

If <src> is a local tar archive in a recognized compression format (identity, gzip, bzip2 or xz) then it is unpacked as a directory. Resources from remote URLs are not decompressed. When a directory is copied or unpacked, it has the same behavior as tar -x: the result is the union of:

1) Whatever existed at the destination path and 2) The contents of the source tree, with conflicts resolved in favor of "2." on a file-by-file basis.

try:

ADD /files/apache-stratos.zip /opt/

and see if the files are there, without further decompression.

With Docker 17.05+ you can use a multi-stage build to avoid creating extra layers.

FROM ... as stage1
# No need to clean up here, these layers will be discarded
ADD /files/apache-stratos.zip /opt/apache-stratos.zip
RUN unzip -q apache-stratos.zip
    && mv apache-stratos-* apache-stratos

FROM ...
COPY --from=stage1 apache-stratos/ apache-stratos/