use chunkah for final image

Containerfile

@@ -1,4 +1,6 @@
-FROM quay.io/fedora/fedora-bootc:44
+ARG CHUNKAH_CONFIG_STR
+
+FROM quay.io/fedora/fedora-bootc:44 AS builder
 
 # Install ZFS
 # we want to keep ALL dnf downloaded packages in dnf cache,
@@ -11,7 +13,17 @@ RUN --mount=type=cache,target=/var/cache/libdnf5 <<EOF
 # dnf install -y kernel-devel-$(uname -r | awk -F'-' '{print $1}')
 dnf install -y https://zfsonlinux.org/fedora/zfs-release-3-1$(rpm --eval "%{dist}").noarch.rpm
 dnf install -y zfs btop borgbackup
-dnf clean all && rm -rf /run/dnf && rm -rf /tmp/*
+rm -rf /run/dnf && rm -rf /tmp/*
 EOF
 
 RUN bootc container lint
+
+FROM quay.io/coreos/chunkah AS chunkah
+ARG CHUNKAH_CONFIG_STR
+RUN --mount=from=builder,src=/,target=/chunkah,ro \
+    --mount=type=bind,target=/run/src,rw \
+        chunkah build --prune /sysroot/ --max-layers 128 \
+          --label ostree.commit- --label ostree.final-diffid- \
+          --output oci:/run/src/out
+
+FROM oci:out