add docker support (#52)

* add docker support

* make shellcheck happy

Dockerfile

@@ -0,0 +1,51 @@
+FROM archlinux:base-devel
+
+# image configuration
+ENV AHRIMAN_ARCHITECTURE="x86_64"
+ENV AHRIMAN_DEBUG=""
+ENV AHRIMAN_FORCE_ROOT=""
+ENV AHRIMAN_OUTPUT="syslog"
+ENV AHRIMAN_PACKAGER="ahriman bot <ahriman@example.com>"
+ENV AHRIMAN_PORT=""
+ENV AHRIMAN_REPOSITORY="aur-clone"
+ENV AHRIMAN_REPOSITORY_ROOT="/var/lib/ahriman/ahriman"
+ENV AHRIMAN_USER="ahriman"
+
+# install environment
+## install git which is required for AUR interaction and go for yay
+RUN pacman --noconfirm -Syu git go
+## create build user
+RUN useradd -m -d /home/build -s /usr/bin/nologin build && \
+    echo "build ALL=(ALL) NOPASSWD: ALL" > /etc/sudoers.d/build
+## install AUR helper
+RUN YAY_DIR="$(runuser -u build -- mktemp -d)" && \
+    git clone https://aur.archlinux.org/yay.git "$YAY_DIR" && \
+    cd "$YAY_DIR" && \
+    runuser -u build -- makepkg --noconfirm --install && \
+    cd - && rm -r "$YAY_DIR"
+## install package dependencies
+RUN runuser -u build -- yay --noconfirm -Sy devtools git pyalpm python-inflection python-passlib python-srcinfo && \
+    runuser -u build -- yay --noconfirm -Sy python-pip && \
+    runuser -u build -- yay --noconfirm -Sy breezy darcs mercurial python-aioauth-client python-aiohttp \
+                                            python-aiohttp-debugtoolbar python-aiohttp-jinja2 python-aiohttp-security \
+                                            python-aiohttp-session python-boto3 python-cryptography python-jinja \
+                                            rsync subversion
+
+# install ahriman
+## copy tree
+COPY --chown=build . "/home/build/ahriman"
+## create package archive and install it
+RUN cd /home/build/ahriman && \
+    make VERSION="$(git describe --tags --abbrev=0)" archlinux && \
+    cp ./*-src.tar.xz package/archlinux && \
+    cd package/archlinux && \
+    runuser -u build -- makepkg --noconfirm --install --skipchecksums && \
+    cd - && rm -r /home/build/ahriman
+
+VOLUME ["/var/lib/ahriman"]
+
+# minimal runtime ahriman setup
+COPY "docker/entrypoint.sh" "/usr/local/bin/entrypoint"
+ENTRYPOINT ["entrypoint"]
+# default command
+CMD ["repo-update"]