Add qcow2 output support

- outputs compressed qcow2 image
- 1GB underlying size, may need changing

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

tools/mkimage-qcow/Dockerfile

@@ -0,0 +1,5 @@
+FROM mobylinux/guestfs:69698aca5bfcb8c4d3a3bbe6d8656be155bf8cd6@sha256:703a7372ada5b3db64a11bc8c60eec06659a1052d9296fa0c556ed3faf75c182
+
+COPY . .
+
+ENTRYPOINT [ "/make-qcow" ]

tools/mkimage-qcow/Makefile

@@ -0,0 +1,27 @@
+.PHONY: tag push
+
+IMAGE=mkimage-qcow
+
+default: push
+
+hash: Dockerfile make-qcow
+	tar cf - $^ | docker build --no-cache -t $(IMAGE):build -
+	docker run --entrypoint sh --rm $(IMAGE):build -c "(cat $^; apt list --installed 2>/dev/null) | sha1sum" | sed 's/ .*//' > hash
+
+push: hash
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		(docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash) && \
+		 docker push mobylinux/$(IMAGE):$(shell cat hash))
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+tag: hash
+	docker pull mobylinux/$(IMAGE):$(shell cat hash) || \
+		docker tag $(IMAGE):build mobylinux/$(IMAGE):$(shell cat hash)
+	docker rmi $(IMAGE):build
+	rm -f hash
+
+clean:
+	rm -f hash
+
+.DELETE_ON_ERROR:

tools/mkimage-qcow/make-qcow

@@ -0,0 +1,55 @@
+#!/bin/sh
+
+set -e
+
+mkdir -p /tmp/image
+cd /tmp/image
+
+# input is a tarball of vmlinuz64 and initrd.img on stdin
+# output is a qcow2 on stdout
+
+mkdir -p files
+
+cd files
+
+# extract. As guestfs base is currently Debian, no compression support
+# only if stdin is a tty, if so need files volume mounted...
+[ -t 0 ] || tar xf -
+
+INITRD="$(find . -name '*.img')"
+KERNEL="$(find . -name vmlinuz64 -or -name '*bzImage')"
+CMDLINE="$*"
+
+[ "$KERNEL" = "./vmlinuz64" ] || mv "$KERNEL" vmlinuz64
+[ "$INITRD" = "./initrd.img" ] || mv "$INITRD" initrd.img
+
+# clean up subdirectories
+find . -mindepth 1 -maxdepth 1 -type d | xargs rm -rf
+
+CFG="DEFAULT linux
+LABEL linux
+    KERNEL /vmlinuz64
+    INITRD /initrd.img
+    APPEND ${CMDLINE}
+"
+
+printf "$CFG" > syslinux.cfg
+
+cd ..
+
+tar cf files.tar -C files .
+
+virt-make-fs --size=1G --type=ext4 --partition files.tar --format=qcow2 disk.qcow
+
+guestfish -a disk.qcow -m /dev/sda1 <<EOF
+  upload /usr/lib/SYSLINUX/mbr.bin /mbr.bin
+  copy-file-to-device /mbr.bin /dev/sda size:440
+  rm /mbr.bin
+  extlinux /
+  part-set-bootable /dev/sda 1 true
+EOF
+
+# compress qcow
+qemu-img convert -f qcow2 -O qcow2 -c disk.qcow disk.qcow2 1>&2
+
+cat disk.qcow2