Improve generation of base images SBOMs

most functional changes are in the related PR that updates the
base_images_sbom_script.py
konflux-ci/build-tasks-dockerfiles#191

Here, we are just updating on how we generate the inputs for this
script.
We are now passing the whole parsed Dockerfile in json format to that
script, which allows us to better parse/detect base images.

Also, the format of the /shared/base_images_digests file was changed.
Previously we could rely on the order of the image references with the
digests in the file. Now we need to provide a mapping from an image
reference as it was used in the Dockerfile to the full image reference
with digests that was used during build and generated by buildah.

The mapping is done as:
<image-reference-used-in-dockerfile>|<full-image-reference-with-digest>

The character that creates the mapping "|" was chosen arbitrarily, just
because it cannot be a valid part of image reference.

KFLUXBUGS-1718

Signed-off-by: mkosiarc <[email protected]>

task/buildah/0.2/buildah.yaml

@@ -279,9 +279,10 @@ spec:
         BUILD_ARG_FLAGS+=("--build-arg=$build_arg")
       done
 
+      
+      dockerfile-json "${BUILD_ARG_FLAGS[@]}" "$dockerfile_copy" > /shared/parsed_dockerfile.json
       BASE_IMAGES=$(
-        dockerfile-json "${BUILD_ARG_FLAGS[@]}" "$dockerfile_copy" |
-          jq -r '.Stages[] | select(.From | .Stage or .Scratch | not) | .BaseName | select(test("^oci-archive:") | not)'
+          jq -r '.Stages[] | select(.From | .Stage or .Scratch | not) | .BaseName | select(test("^oci-archive:") | not)' /shared/parsed_dockerfile.json
       )
 
       BUILDAH_ARGS=()
@@ -463,12 +464,10 @@ spec:
 
       touch /shared/base_images_digests
       for image in $BASE_IMAGES; do
-        buildah images --format '{{ .Name }}:{{ .Tag }}@{{ .Digest }}' --filter reference="$image" >> /shared/base_images_digests
+        base_image_digest=$(buildah images --format '{{ .Name }}:{{ .Tag }}@{{ .Digest }}' --filter reference="$image")
+        echo "$image|$base_image_digest" >> /shared/base_images_digests
       done
 
-      # Needed to generate base images SBOM
-      echo "$BASE_IMAGES" > /shared/base_images_from_dockerfile
-
     securityContext:
       capabilities:
         add:
@@ -558,7 +557,7 @@ spec:
       echo "Adding base images data to sbom-cyclonedx.json"
       python3 /scripts/base_images_sbom_script.py \
         --sbom=sbom-cyclonedx.json \
-        --base-images-from-dockerfile=/shared/base_images_from_dockerfile \
+        --parsed-dockerfile=/shared/parsed_dockerfile.json \
         --base-images-digests=/shared/base_images_digests
     workingDir: $(workspaces.source.path)
     securityContext: