ingress-controller/ci: check docker base images

scripts/check-docker-images

@@ -0,0 +1,20 @@
+#!/usr/bin/bash
+set -euo pipefail
+
+_project_root="$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)/.."
+for _f in $(find "$_project_root" -name "*Dockerfile*"); do
+    echo "checking $_f"
+    for _img in $(sed -n -r -e 's/^FROM ([^:]*)(:[^@]*)(@sha256[^ ]*).*$/\1\2\3/p' "$_f"); do
+        echo "- $_img"
+        _media_type="$(
+            docker buildx imagetools inspect \
+                --format='{{print .Manifest.MediaType }}' \
+                "$_img"
+        )"
+
+        if [[ "$_media_type" != "application/vnd.oci.image.index.v1+json" && "$_media_type" != "application/vnd.docker.distribution.manifest.list.v2+json" ]]; then
+            echo "not a multi-platform manifest"
+            exit 1
+        fi
+    done
+done