Use multi-stage build to reduce the image size

docker/Dockerfile.prod

@@ -1,45 +1,57 @@
 ARG PYTHON_VERSION="3.8.13-slim-bullseye"
-FROM python:${PYTHON_VERSION}
+FROM python:${PYTHON_VERSION} AS backend-builder
 
-CMD ["python3"]
-
-WORKDIR /backend
-
-ENV PYTHONDONTWRITEBYTECODE 1
-ENV PYTHONUNBUFFERED 1
-
-RUN groupadd -g 61000 doccano \
-  && useradd -g 61000 -l -M -s /bin/false -u 61000 doccano
-
-COPY --chown=doccano:doccano backend/pyproject.toml backend/poetry.lock /backend/
-SHELL ["/bin/bash", "-o", "pipefail", "-c"]
-
-# hadolint ignore=DL3013,DL3008
+# hadolint ignore=DL3008
 RUN apt-get update \
  && apt-get install -y --no-install-recommends \
     netcat=1.* \
     libpq-dev=13.* \
     unixodbc-dev=2.* \
     g++=4:* \
+    libssl-dev=1.* \
     curl \
- && pip install --upgrade --no-cache-dir pip==22.2.2 \
+ && apt-get clean \
+ && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /tmp
+COPY backend/pyproject.toml backend/poetry.lock /tmp/
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
+
+RUN pip install -U --no-cache-dir pip==22.2.2 \
  && curl -sSL https://install.python-poetry.org | python - \
  && export PATH="/root/.local/bin:$PATH" \
- && poetry config virtualenvs.create false \
- && poetry install --no-dev --no-root \
- && poetry add psycopg2-binary \
+ && poetry export --without-hashes -o /requirements.txt \
+ && echo "psycopg2-binary==2.8.6" >> /requirements.txt \
+ && pip install --no-cache-dir -r /requirements.txt
+
+FROM python:${PYTHON_VERSION} AS runtime
+
+WORKDIR /backend
+
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends \
+    libpq-dev=13.* \
+    unixodbc-dev=2.* \
+    libssl-dev=1.* \
  && apt-get clean \
  && rm -rf /var/lib/apt/lists/*
 
+RUN groupadd -g 61000 doccano \
+  && useradd -g 61000 -l -M -s /bin/false -u 61000 doccano
+
+COPY --from=backend-builder /usr/local/lib/python3.8/site-packages /usr/local/lib/python3.8/site-packages
+COPY --from=backend-builder /usr/local/bin/celery /usr/local/bin/celery
+COPY --from=backend-builder /usr/local/bin/gunicorn /usr/local/bin/gunicorn
 COPY --chown=doccano:doccano tools/ /opt/bin/
+COPY --chown=doccano:doccano backend/ /backend/
 RUN mkdir -p /backend/staticfiles \
   && mkdir -p /backend/client/dist/static \
   && mkdir -p /backend/media \
   && mkdir -p /backend/filepond-temp-uploads \
   && chown -R doccano:doccano /backend/
 
-COPY --chown=doccano:doccano ./backend/ /backend/
-RUN ls /backend
+ENV PYTHONDONTWRITEBYTECODE 1
+ENV PYTHONUNBUFFERED 1
 USER doccano:doccano
 VOLUME /backend/staticfiles