Add new _prefetch helper for fetching and caching images.
Use it in a few places, most importantly 120-load.bats
where our teardown() now runs 'rmi -af'.
Reason: in #17911 we discovered that podman save + load do
not actually preserve the image: annotations and other metadata
are lost. This means that a test which runs after 120-load.bats
is operating on a different $IMAGE than a test which runs before.
This is not a problem except in very obscure corner cases, like
one fixed in #18542, but it seems irresponsible to just handwave
that issue away
The _prefetch function uses skopeo for fetching and saving
images, because skopeo preserves digests and metadata.
[Side note for posterity: I tried amending basic_setup() to
always rmi -a + prefetch, instead of the current images -a +
rmi unwanted ones. That slowed down system tests by 10 minutes,
presumably because loads are much slower than queries. I reverted
that change and am documenting it as a reminder of why we do things
the way we do.]
Signed-off-by: Ed Santiago <santiago@redhat.com>
Ed Santiago
José Guilherme Vanz