Use Docker instead of Vagrant for generate images

Fixes #2

tools/qemu-debian-img/Dockerfile

@@ -0,0 +1,35 @@
+# Copyright 2018 Mikhail Klementev. All rights reserved.
+# Use of this source code is governed by a AGPLv3 license
+# (or later) that can be found in the LICENSE file.
+#
+# Usage:
+#
+#     $ docker build -t gen-ubuntu1804-image .
+#     $ docker run --privileged -v $(pwd):/shared -t gen-ubuntu1804-image
+#
+# centos7.img will be created in current directory. You can change $(pwd) to
+# different directory to use different destination for image.
+#
+FROM ubuntu:18.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+RUN apt update
+RUN apt install -y debootstrap qemu
+RUN apt install -y linux-image-generic
+
+ENV TMPDIR=/tmp/ubuntu
+ENV IMAGEDIR=/tmp/image
+ENV IMAGE=/shared/ubuntu1804.img
+ENV REPOSITORY=http://archive.ubuntu.com/ubuntu
+ENV RELEASE=bionic
+
+RUN mkdir $IMAGEDIR
+
+# Must be runned with --privileged because of /dev/loop
+CMD debootstrap --include=openssh-server $RELEASE $TMPDIR $REPOSITORY && \
+	/shared/setup.sh $TMPDIR && \
+	qemu-img create $IMAGE 2G && \
+	mkfs.ext4 -F $IMAGE && \
+	mount -o loop $IMAGE $IMAGEDIR && \
+	cp -a $TMPDIR/* $IMAGEDIR/ && \
+	umount $IMAGEDIR