In downstream contexts, it's extremely useful to be able to combine
all the "testable" images in Kubernetes into a single repo so that
a user could mirror these offline in one chunk, and audit the set of
images for changes. For instance, within OpenShift we would like to
have a single place we can place all the images used by all the tests
with a single authentication scheme. While some images are not "real"
and can't be mirrored (for instance, the images that point to an
auth protected registry), that is not the majority.
This code makes it possible to specify an environment variable
KUBE_TEST_REPO that maps the static strings of the registry to a
single repository by placing the uniqueness in a tag. For instance:
KUBE_TEST_REPO=quay.io/openshift/community-e2e-images
would translate `k8s.gcr.io/prometheus-to-sd:v0.5.0` to `quay.io/openshift/community-e2e-images:e2e-30-k8s-gcr-io-prometheus-to-sd-v0-5-0-6JI59Yih4oaj3oQOjRfhyQ`.
The tag is a safe form of the name, plus the index (the constant within
manifest.go), plus a hash of the full input. The length of the tag is
constrained to the minimum of hash + index + the safe name.
The public method is changed to return two maps - index to original
name and index to test repo name. These maps would be the same if
the env var is not set.
The multi-arch container images used in tests live in quay.io which
doesn't support nesting. By making the /volume/ images repo configurable,
we are able to override them despite our current limitation.
Signed-off-by: Rafael Fonseca <r4f4rfs@gmail.com>
