This change fixes that by properly "replaying" the Dockerfile and mutating the config when
calculating cache keys. Previously we were looking at the wrong cache key for each command
when there was more than one.
* Rework cache key generation a bit.
Cache keys are now based on the previous commands, rather than the previous state
of the filesystem.
* Refactor command interface a bit, only cache the context for commands that use it.
CacheCommand returns true if the command should be cached. Currently,
it's only true for RUN but can be added to ADD/COPY later on (these are
different since the contents of files for ADD/COPY need to be included
in the cache key generation).
I also changed CreatedBy to String so that we can log each command
before cache extraction or regular execution takes place.
* Vendor changes for go-containerregistry switch.
* Manual changes for go-containerregistry switch.
The biggest change is refactoring the tarball unpacking.
* Pull more of container-diff out.
* More vendor removals.
* More unit tests.
* adding VOLUME command
* proper test project
* general fixes
* fixing project name
* fixing volume unit test
* fixing integration test
* adding tests
* adding util test
* fixing test
* actually create the volume mounted directory
* fix test