I added a KanikoStage to hold each stage of the Dockerfile along with
information about each stage that would be useful later on.
The new KanikoStage type holds the stage itself, along with some
additional information:
1. FinalStage -- whether the current stage is the final stage
2. BaseImageStoredLocally/BaseImageIndex -- whether the base image for
this stage is stored locally, and if so what the index of the base image
is
3. SaveStage -- whether this stage needs to be saved for use in a future
stage
This is the first part of a larger refactor for building stages, which
will later make it easier to add layer caching.
This test had previously (before #231) been making a change to a file in
the kaniko dir, then checking that it isn't being snapshotted. This was
to test the whitelisting logic, which makes sure that changes to /kaniko
aren't included in images. However the test creates a temporary dir, so
the kaniko dir is actually in /tmp/<some temp dir>/kaniko, and
in #231 the logic was simplified to no longer have a special case for
tests. The test continued to pass because `MaybeAdd` noticed that the
kaniko file wasn't changing, and didn't add it. After changing this to
always add the files, it revealed that this was left behind by accident.
I also opened #307 to add integration test coverage for this logic.
I also marked `CheckErrorAndDeepEqual` as a helper function so that when
it fails, the line number reported is where that was called.