Use docker run to run tests and interactive containers

Using docker build is slower and needs lots of Dockerfiles,
while a single image with a careful script can accept any type
of image, either with `-v` to share into `/tmp` for interactive
use (where you need the input and a tty, or by adding a tarball
for cases where there is no login such as running tests, so you
can still use a remote daemon in these cases.

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

base/qemu/Dockerfile

@@ -0,0 +1,13 @@
+FROM alpine:3.5
+
+RUN \
+  apk update && apk upgrade && \
+  apk add --no-cache \
+  libarchive-tools \
+  qemu-img \
+  qemu-system-arm \
+  qemu-system-x86_64 \
+  && true
+
+COPY . .
+ENTRYPOINT ["/qemu.sh"]

base/qemu/Makefile

@@ -0,0 +1,29 @@
+.PHONY: tag push
+
+BASE=alpine:3.5
+IMAGE=qemu
+
+default: push
+
+hash: Dockerfile qemu.sh
+	DOCKER_CONTENT_TRUST=1 docker pull $(BASE)
+	tar cf - $^ | docker build --no-cache -t $(IMAGE):build -
+	docker run --rm --entrypoint /bin/sh $(IMAGE):build -c 'cat Dockerfile qemu.sh /lib/apk/db/installed | sha1sum' | sed 's/ .*//' > $@
+
+push: hash
+	docker pull mobylinux/$(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:

base/qemu/qemu.sh

@@ -0,0 +1,41 @@
+#!/bin/sh
+
+set -e
+
+cd /tmp
+
+# extract. BSD tar auto recognises compression, unlike GNU tar
+# only if stdin is a tty, if so need files volume mounted...
+[ -t 0 ] || bsdtar xzf -
+
+TGZ="$(find . -name '*.tgz' -or -name '*.tar.gz')"
+[ -n "$TGZ" ] && bsdtar xzf "$TGZ"
+
+ISO="$(find . -name '*.iso')"
+RAW="$(find . -name '*.raw')"
+INITRD="$(find . -name '*.img')"
+KERNEL="$(find . -name vmlinuz64 -or -name bzImage)"
+
+if [ -n "$ISO" ]
+then
+	ARGS="-cdrom $ISO -drive file=systemdisk.img,format=raw"
+elif [ -n "$RAW" ]
+then
+	# should test with more drives
+	ARGS="-drive file=$RAW,format=raw"
+elif [ -n "KERNEL" ]
+then
+	ARGS="-kernel $KERNEL"
+	if [ -n "$INITRD" ]
+	then
+		ARGS="$ARGS -initrd $INITRD"
+	fi
+	ARGS="$ARGS -append console=ttyS0 -drive file=systemdisk.img,format=raw"
+else
+	echo "no recognised boot media" >2
+	exit 1
+fi
+
+echo "$ARGS" | grep -q systemdisk && qemu-img create -f raw systemdisk.img 256M
+
+qemu-system-x86_64 -device virtio-rng-pci -serial stdio -vnc none -m 1024 $ARGS $*