Move container metadata into the Containerfile

Less bespoke buildsystem.

Containerfile

@@ -66,6 +66,15 @@ EORUN
 # At this point we're done with the builder image and we have our OCI archive.
 
 FROM oci-archive:./out.ociarchive
+# We've cargo culted this one around, xref https://pagure.io/fork/cverna/fedora-kiwi-descriptions/c/a12446bbe98404cb4b30d4b07505ecf71a88dfcb
+ENV container=oci
+# Required for systemd being the default entrypoint
+STOPSIGNAL SIGRTMIN+3
+# https://containers.github.io/bootc/bootc-images.html#standard-metadata-for-bootc-compatible-images
+LABEL containers.bootc 1
+# This is our recommended way to link between the base image and
+# a tool to make disk images.
+LABEL bootc.diskimage-builder quay.io/centos-bootc/bootc-image-builder
 # Need to reference builder here to force ordering. But since we have to run
 # something anyway, we might as well cleanup after ourselves.
 RUN --mount=type=bind,from=builder,src=.,target=/var/tmp \

fedora-bootc-config.json

@@ -1,10 +0,0 @@
-{
-    "Labels": {
-        "containers.bootc": "1",
-        "bootc.diskimage-builder": "quay.io/centos-bootc/bootc-image-builder",
-    },
-    "StopSignal": "SIGRTMIN+3",
-    "Env": [
-        "container=oci"
-    ]
-}