Add working-dir based Dockerfile

Many thanks to @anime-shed's input!
Closes #68

Dockerfile

@@ -0,0 +1,52 @@
+# This is the Dockerfile that builds an image form the current directory.
+# It is provided as-is; the Bugsink team does not use this in their own
+# development. Tips:
+
+# * Configure your database/filestore/etc _outside_ of the current path
+#     to avoid copying them into the image.
+
+ARG PYTHON_VERSION=3.12
+
+# Build image: non-slim, in particular to build the mysqlclient wheel
+FROM python:${PYTHON_VERSION} AS build
+
+# mysqlclient is not available as a .whl on PyPI, so we need to build it from
+# source and store the .whl. This is both the most expensive part of the build
+# and the one that is least likely to change, so we do it first.
+RUN --mount=type=cache,target=/var/cache/buildkit/pip \
+    pip wheel --wheel-dir /wheels mysqlclient
+
+# Actual image (based on slim)
+FROM python:${PYTHON_VERSION}-slim
+
+ENV PYTHONUNBUFFERED=1
+
+ENV PORT=8000
+
+WORKDIR /app
+
+# mysqlclient dependencies; needed here too, because the built wheel depends on .o files
+RUN apt update && apt install default-libmysqlclient-dev -y
+
+COPY --from=build /wheels /wheels
+
+RUN --mount=type=cache,target=/var/cache/buildkit/pip \
+    pip install --find-links /wheels --no-index mysqlclient
+
+RUN --mount=type=cache,target=/var/cache/buildkit/pip \
+    pip install "psycopg[binary]"
+
+COPY requirements.txt /app/
+RUN --mount=type=cache,target=/var/cache/buildkit/pip \
+    pip install -r requirements.txt
+
+COPY . /app/
+COPY bugsink/conf_templates/docker.py.template bugsink_conf.py
+
+# Git is needed by setuptools_scm to get the version from the git tag
+RUN apt update && apt install -y git
+RUN pip install -e .
+
+RUN ["bugsink-manage", "migrate", "snappea", "--database=snappea"]
+
+CMD [ "monofy", "bugsink-manage", "check", "--deploy", "--fail-level", "WARNING", "&&", "bugsink-manage", "migrate", "&&", "bugsink-manage", "prestart", "&&", "gunicorn", "--bind=0.0.0.0:$PORT", "--workers=10", "--access-logfile", "-", "bugsink.wsgi", "|||", "bugsink-runsnappea"]

Dockerfile.fromwheel

@@ -38,7 +38,10 @@ RUN --mount=type=cache,target=/var/cache/buildkit/pip \
 #     breaks the idea of "just build the wheel" (requirements.txt is whatever
 #     it happens to be right now, not what it was at the time the wheel was
 #     built)
-
+# 
+# Moreover, there's the argument of image _size_ rather than build time, and
+# copying over all wheels instead of just their unpacked equivalents increases
+# that.
 
 # Actual image (based on slim)
 FROM python:${PYTHON_VERSION}-slim