Address code review feedback

- Add *.raw.xz to .gitignore and .dockerignore
- Use long-form xz options (--extreme, --stdout, --decompress)
- Drop --threads=0 (already the default)
- Split qcow2.xz build into separate qcow2 and xz rules with
  .INTERMEDIATE so make handles cleanup on failure
- Improve error message when ext4 partition is not found
- List all three build types in README
- Add kiwi-runtime.yml with xz -0 so kiwi does not waste time on
  compression we discard and recompress at -9 --extreme

Signed-off-by: Jan Dubois <jan.dubois@suse.com>

Author: jandubois

.dockerignore

@@ -1,2 +1,3 @@
 distro.tar.xz
 distro.qcow2.xz
+distro.raw.xz

.gitignore

@@ -1,3 +1,4 @@
 /root/build/
 *.qcow2.xz
+*.raw.xz
 *.tar.xz

Dockerfile

@@ -20,8 +20,14 @@ RUN --mount=type=cache,target=/root/.cache/go-build --mount=type=cache,target=/g
 FROM registry.opensuse.org/opensuse/bci/kiwi:10 AS builder
 ARG type=qcow2.xz
 ARG NERDCTL_VERSION
+# The BCI kiwi image ships /etc/kiwi.yml with mapper and runtime_checks
+# settings required for building inside Docker. Append xz -0 so kiwi
+# does not waste time on compression we discard and recompress at
+# xz -9 --extreme in Makefile.docker. Using --config would replace the
+# existing file and lose the mapper setting, breaking loop devices.
 RUN --mount=type=cache,target=/var/cache/zypp \
-    zypper --non-interactive install parted
+    zypper --non-interactive install parted && \
+    echo -e '\nxz:\n  - options: '\''-0'\''' >> /etc/kiwi.yml
 WORKDIR /build
 COPY . /description
 COPY --from=gobuild /go/bin/* /description/root/usr/local/bin/

Makefile.docker

@@ -33,18 +33,20 @@ rancher-desktop-distro.%.tar.xz: config.kiwi config.sh ${INPUTS}
 #            xz-compressed for storage/transfer.
 /build/distro.raw.xz: /build/rancher-desktop-distro.$(ARCH)-0.100.0.raw
 	./clean-rootfs.sh $<
-	xz -9e -T0 -c $< > $@
+	xz -9 --extreme --stdout $< > $@
 
-/build/distro.qcow2.xz: /build/rancher-desktop-distro.$(ARCH)-0.100.0.raw
+/build/distro.qcow2: /build/rancher-desktop-distro.$(ARCH)-0.100.0.raw
 	./clean-rootfs.sh $<
-	qemu-img convert -c -f raw $< -O qcow2 -o compression_type=zstd,compat=1.1 $(@:.xz=)
-	xz -9e -T0 -c $(@:.xz=) > $@
-	rm $(@:.xz=)
+	qemu-img convert -c -f raw $< -O qcow2 -o compression_type=zstd,compat=1.1 $@
+
+/build/distro.qcow2.xz: /build/distro.qcow2
+	xz -9 --extreme --stdout $< > $@
 
 # Recompress the tarball kiwi leaves behind. Kiwi runs xz in threaded
 # mode with 24 MiB blocks, which loses a meaningful chunk of ratio to
-# block boundaries; a single xz -9e pass is ~14% smaller.
+# block boundaries; a single xz -9 --extreme pass is ~14% smaller.
 /build/distro.tar.xz: /build/rancher-desktop-distro.$(ARCH)-0.100.0.tar.xz
-	xz -dc $< | xz -9e -T0 > $@
+	xz --decompress --stdout $< | xz -9 --extreme > $@
 
+.INTERMEDIATE: /build/distro.qcow2
 .DELETE_ON_ERROR: # Avoid half-downloaded files

README.md

@@ -5,8 +5,9 @@ Desktop.
 
 The distribution is built using `docker`:
 ```sh
-make TYPE=qcow2.xz # For Linux/darwin hosts
-make TYPE=tar.xz # For WSL hosts
+make TYPE=raw.xz   # For macOS/VZ hosts (default)
+make TYPE=qcow2.xz # For Linux/qemu hosts
+make TYPE=tar.xz   # For WSL hosts
 ```
 
 To cross-compile for a non-native architecture, set `GOARCH` to the target

clean-rootfs.sh

@@ -22,7 +22,7 @@ for p in /dev/mapper/"$(basename "$LOOP")"p*; do
     ROOT=$p
     break
 done
-test -n "$ROOT"
+: ${ROOT:?Failed to find ext4 partition in $RAW}
 
 MNT=$(mktemp -d)
 mount "$ROOT" "$MNT"