📦 chore(base.Dockerfile): add base Dockerfile for Python project setup

🚧 feat(base.Dockerfile): create python-base stage with shared environment variables
🚧 feat(base.Dockerfile): create builder-base stage for building dependencies and creating virtual environment
🚧 feat(base.Dockerfile): create development stage for development and testing

base.Dockerfile

@@ -0,0 +1,87 @@
+
+
+# syntax=docker/dockerfile:1
+# Keep this syntax directive! It's used to enable Docker BuildKit
+
+# Based on https://github.com/python-poetry/poetry/discussions/1879?sort=top#discussioncomment-216865
+# but I try to keep it updated (see history)
+
+################################
+# PYTHON-BASE
+# Sets up all our shared environment variables
+################################
+FROM python:3.10-slim as python-base
+
+# python
+ENV PYTHONUNBUFFERED=1 \
+    # prevents python creating .pyc files
+    PYTHONDONTWRITEBYTECODE=1 \
+    \
+    # pip
+    PIP_DISABLE_PIP_VERSION_CHECK=on \
+    PIP_DEFAULT_TIMEOUT=100 \
+    \
+    # poetry
+    # https://python-poetry.org/docs/configuration/#using-environment-variables
+    POETRY_VERSION=1.5.1 \
+    # make poetry install to this location
+    POETRY_HOME="/opt/poetry" \
+    # make poetry create the virtual environment in the project's root
+    # it gets named `.venv`
+    POETRY_VIRTUALENVS_IN_PROJECT=true \
+    # do not ask any interactive question
+    POETRY_NO_INTERACTION=1 \
+    \
+    # paths
+    # this is where our requirements + virtual environment will live
+    PYSETUP_PATH="/opt/pysetup" \
+    VENV_PATH="/opt/pysetup/.venv"
+
+
+# prepend poetry and venv to path
+ENV PATH="$POETRY_HOME/bin:$VENV_PATH/bin:$PATH"
+
+
+################################
+# BUILDER-BASE
+# Used to build deps + create our virtual environment
+################################
+FROM python-base as builder-base
+RUN apt-get update \
+    && apt-get install --no-install-recommends -y \
+    # deps for installing poetry
+    curl \
+    # deps for building python deps
+    build-essential
+
+# install poetry - respects $POETRY_VERSION & $POETRY_HOME
+# The --mount will mount the buildx cache directory to where
+# Poetry and Pip store their cache so that they can re-use it
+RUN --mount=type=cache,target=/root/.cache \
+    curl -sSL https://install.python-poetry.org | python3 -
+
+# copy project requirement files here to ensure they will be cached.
+WORKDIR $PYSETUP_PATH
+COPY poetry.lock pyproject.toml ./
+COPY ./src/backend ./src/backend
+# Copy README.md to the build context
+COPY README.md .
+# install runtime deps - uses $POETRY_VIRTUALENVS_IN_PROJECT internally
+RUN --mount=type=cache,target=/root/.cache \
+    poetry install --without=dev
+
+
+################################
+# DEVELOPMENT
+# Image used during development / testing
+################################
+FROM python-base as development
+WORKDIR $PYSETUP_PATH
+
+# copy in our built poetry + venv
+COPY --from=builder-base $POETRY_HOME $POETRY_HOME
+COPY --from=builder-base $PYSETUP_PATH $PYSETUP_PATH
+
+# quicker install as runtime deps are already installed
+RUN --mount=type=cache,target=/root/.cache \
+    poetry install --with=dev