This change calculates the exact files and directories needed between
stages used in the COPY command. Instead of saving the entire
stage as a tarball, we now save only the necessary files.
We previously had an optimization that would skip snapshotting mutli-stage images
when in an intermediate stage, until the very end.
This conflicted with another optimization to avoid snapshotting when no files had changed.
* parse arg commands at the top of dockerfiles
* fix pointer reference bug and remove debugging
* fixing tests
* account for meta args with no value
* don't take fs snapshot if / is the only changed path
* move metaArgs inside KanikoStage
* removing unused property
* check for any directory instead of just /
* remove unnecessary check
As mentioned in #346, if only ENTRYPOINT is set in a stage then any
CMD inherited from a parent should be cleared.
If both entrypoint and cmd are set then nothing should change.
I added a function and unit test to review the config file after building a stage
which clears out config.Cmd if ENTRYPOINT was declared but CMD wasn't.
I also added an integration test to make sure this works, which should
be tested by the preexisting container-diff --metadata test.