* Extend .dockerignore integration test with copies in later stages
.dockerignore should continue to apply when copying from the build context in later stages, but it currently doesn't
* Replace excluded global with passed along FileContext struct
This new FileContext struct allows much cleaner handling of context specific file exclusions.
The global excluded file state is no longer needed.
Additionally this also fixes the issue where excluded files aren't being applied for build context copies in later build stages.
This PR adds support for the dockerignore file. Previously when kaniko
had support for the dockerignore file, kaniko first went through the
build context and deleted files that were meant to be ignored. This
resulted in a really bad bug where files in user mounted volumes would
be deleted (my bad).
This time around, instead of modifying the build context at all, kaniko
will check if a file should be excluded when executing ADD/COPY
commands. If a file should be excluded (based on the .dockerignore) it
won't be copied over from the buildcontext and shouldn't end up in the
final image.
I also added a .dockerignore file and Dockerfile as an integration test,
which should fail if the dockerignore is not being processed correctly or if files aren't being excluded correctly.
Also, I removed all the integration testing from the previous version of the
dockerignore support.