build isolation oci for arm64 builds

podman-build-publish/action.yaml

@@ -31,6 +31,12 @@ inputs:
       Example: "ACT_RUNNER_VERSION=0.2.11"
     required: false
     default: ""
+  build-isolation:
+    description: |
+      Podman build isolation mode.
+      Supported values: "chroot" or "oci".
+    required: false
+    default: "chroot"
   push:
     description: |
       Whether to push tags to the registry after build.
@@ -75,6 +81,15 @@ runs:
         echo "PODMAN_STORAGE_DRIVER=${selected_driver}" >> "${GITHUB_ENV}"
         echo "PODMAN_STORAGE_OPT=${selected_storage_opt}" >> "${GITHUB_ENV}"
 
+        case "${{ inputs.build-isolation }}" in
+          chroot|oci)
+            ;;
+          *)
+            echo "ERROR: unsupported build-isolation '${{ inputs.build-isolation }}' (expected 'chroot' or 'oci')" >&2
+            exit 1
+            ;;
+        esac
+
         # Validate tags early so failures are caught before build starts
         mapfile -t tags < <(printf '%s\n' "${{ inputs.tags }}" | tr ', ' '\n\n' | sed '/^$/d')
         if [[ ${#tags[@]} -eq 0 ]]; then
@@ -122,7 +137,7 @@ runs:
         fi
 
         image_base="registry.noctrl.eu/${{ inputs.image-name }}"
-        build_cmd=(podman "${podman_args[@]}" build --isolation chroot -f "${{ inputs.containerfile }}")
+        build_cmd=(podman "${podman_args[@]}" build --isolation "${{ inputs.build-isolation }}" -f "${{ inputs.containerfile }}")
 
         # Add build args
         while IFS= read -r build_arg; do