tests: pull stability-test images from the ghcr.io mirror

The stability tests pulled their container images straight from Docker Hub:
cassandra_stress.sh pulled docker.io/library/cassandra and the stress-ng
image was built FROM ubuntu:20.04 (Docker Hub). Both are now sourced from the
kata-containers ghcr.io mirror:

  * cassandra_stress.sh uses a substitutable REGISTRY (default
    ghcr.io/kata-containers) for the cassandra image.
  * common_stability.bash prefers ghcr.io/kata-containers for the ubuntu base,
    keeping the previous registries as fallbacks.
  * the stress-ng Dockerfile becomes Dockerfile.in with an @UBUNTU_REGISTRY@
    placeholder so it flows through the existing registry-fallback logic; the
    generated Dockerfile is gitignored.

Only Docker Hub sources are migrated here; quay.io/registry.k8s.io test images
are left untouched.

Authored-by: Cursor <cursor@cursor.com>
Signed-off-by: Fabiano Fidêncio <ffidencio@nvidia.com>

tests/stability/cassandra_stress.sh

@@ -11,9 +11,14 @@ SCRIPT_PATH=$(dirname "$(readlink -f "$0")")
 # shellcheck source=/dev/null
 source "${SCRIPT_PATH}/common_stability.bash"
 
-IMAGE="docker.io/library/cassandra:latest"
+# Pull from the kata-containers ghcr.io mirror by default instead of Docker
+# Hub. Override REGISTRY to use a different source.
+REGISTRY="${REGISTRY:-ghcr.io/kata-containers}"
+IMAGE="${REGISTRY}/cassandra:latest"
 CONTAINER_NAME="${CONTAINER_NAME:-cassandra_test}"
-DOCKER_IMAGE="cassandra:latest"
+DOCKER_IMAGE="${IMAGE}"
+# Local archive name; must be slash-free as it is used as a filename.
+IMAGE_TAR="cassandra.tar"
 PAYLOAD_ARGS="${PAYLOAD_ARGS:-tail -f /dev/null}"
 CMD="cassandra -R"
 
@@ -25,9 +30,9 @@ function main() {
 	# DOCKER_EXE, CTR_EXE, and CTR_RUNTIME are set by common.bash's init_env
 	# shellcheck disable=SC2154
 	sudo -E "${DOCKER_EXE}" pull "${DOCKER_IMAGE}"
-	sudo -E "${DOCKER_EXE}" save -o "${DOCKER_IMAGE}.tar" "${DOCKER_IMAGE}"
+	sudo -E "${DOCKER_EXE}" save -o "${IMAGE_TAR}" "${DOCKER_IMAGE}"
 	# shellcheck disable=SC2154
-	sudo -E "${CTR_EXE}" i import "${DOCKER_IMAGE}.tar"
+	sudo -E "${CTR_EXE}" i import "${IMAGE_TAR}"
 
 	# shellcheck disable=SC2154
 	sudo -E "${CTR_EXE}" run -d --runtime "${CTR_RUNTIME}" "${IMAGE}" "${CONTAINER_NAME}" sh -c "${PAYLOAD_ARGS}"

tests/stability/common_stability.bash

@@ -19,9 +19,12 @@ KATA_HYPERVISOR="${KATA_HYPERVISOR:-qemu}"
 http_proxy="${http_proxy:-}"
 https_proxy="${https_proxy:-}"
 
+# Prefer the kata-containers ghcr.io mirror over Docker Hub; the remaining
+# entries are kept as fallbacks. Override REGISTRY to change the primary source.
 declare -A registries
 registries[ubuntu]=\
-"docker.io/library
+"${REGISTRY:-ghcr.io/kata-containers}
+docker.io/library
 public.ecr.aws/lts
 mirror.gcr.io/library
 quay.io/libpod"

tests/stability/stressng_dockerfile/.gitignore

@@ -0,0 +1,3 @@
+# Generated at test time from Dockerfile.in by common_stability.bash
+# (@UBUNTU_REGISTRY@ is substituted with the first working registry).
+/Dockerfile

tests/stability/stressng_dockerfile/Dockerfile.in

@@ -2,7 +2,7 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-FROM ubuntu:20.04
+FROM @UBUNTU_REGISTRY@/ubuntu:20.04
 
 # Version of the Dockerfile
 LABEL DOCKERFILE_VERSION="1.0"