Convert to pyproject setup

Dockerfile

@@ -1,8 +1,33 @@
-FROM python:3.11.5-alpine3.18
+FROM python:3.11.5-alpine3.18 AS base
 
-WORKDIR /code
-COPY ./requirements.txt /code/requirements.txt
-RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt
-COPY ./gocardless_membership_exporter /code/gocardless_membership_exporter
+FROM base AS builder
 
+ENV PYTHONFAULTHANDLER=1 \
+  PYTHONUNBUFFERED=1 \
+  PYTHONHASHSEED=random \
+  PIP_NO_CACHE_DIR=off \
+  PIP_DISABLE_PIP_VERSION_CHECK=on \
+  PIP_DEFAULT_TIMEOUT=100 \
+  POETRY_NO_INTERACTION=1 \
+  POETRY_VIRTUALENVS_CREATE=false \
+  PATH="$PATH:/runtime/bin" \
+  PYTHONPATH="$PYTHONPATH:/runtime/lib/python3.11/site-packages" \
+  # Versions:
+  POETRY_VERSION=1.5.1
+
+# System deps:
+RUN apk add build-base unzip wget python3-dev libffi-dev
+RUN pip install "poetry==$POETRY_VERSION"
+
+WORKDIR /src
+
+# Generate requirements and install *all* dependencies.
+COPY pyproject.toml poetry.lock /src/
+RUN poetry export --dev --without-hashes --no-interaction --no-ansi -f requirements.txt -o requirements.txt
+RUN pip install --prefix=/runtime --force-reinstall -r requirements.txt
+
+FROM base AS runtime
+COPY --from=builder /runtime /usr/local
+COPY ./gocardless_membership_exporter /app/gocardless_membership_exporter
+WORKDIR /app
 CMD ["python", "-m", "gocardless_membership_exporter"]