build: add docker setting

Dockerfile

@@ -1,7 +1,7 @@
-FROM python:3.10.13-slim-bookworm
+FROM python:3.10.13-slim-bookworm  as python-base
 
 # `FLASK_ENV` arg is used to make prod / dev builds:
-ARG FLASK_ENV=production
+ARG FLASK_ENV="production"
   # Needed for fixing permissions of files created by Docker:
 
 ENV FLASK_ENV=${FLASK_ENV} \
@@ -15,29 +15,28 @@ ENV FLASK_ENV=${FLASK_ENV} \
   PIP_DISABLE_PIP_VERSION_CHECK=1 \
   PIP_DEFAULT_TIMEOUT=100 \
   PIP_ROOT_USER_ACTION=ignore \
-  # tini:
-  TINI_VERSION=v0.19.0 \
   # poetry:
   POETRY_VERSION=1.6.1 \
   POETRY_NO_INTERACTION=1 \
   POETRY_VIRTUALENVS_CREATE=false \
   POETRY_CACHE_DIR='/var/cache/pypoetry' \
-  POETRY_HOME='/usr/local'
+  POETRY_HOME='/usr/local' \
+  # paths
+  # this is where our requirements + virtual environment will live
+  PYSETUP_PATH="/opt/pysetup" \
+  VENV_PATH="/opt/pysetup/.venv"
 
 
-WORKDIR /app
-
+# prepend poetry and venv to path
+ENV PATH="$POETRY_HOME/bin:$VENV_PATH/bin:$PATH"
 # System deps (we don't use exact versions because it is hard to update them,
 # pin when needed):
 # hadolint ignore=DL3008
+FROM python-base as builder-base
 RUN apt-get update && apt-get upgrade -y \
   && apt-get install --no-install-recommends -y \
-    bash \
-    brotli \
     build-essential \
     curl \
-    git \
-    libpq-dev \
   # Installing `poetry` package manager:
   # https://github.com/python-poetry/poetry
   && curl -sSL 'https://install.python-poetry.org' | python - \
@@ -49,24 +48,28 @@ RUN apt-get update && apt-get upgrade -y \
 
 
 # Copy only requirements, to cache them in docker layer
+WORKDIR $PYSETUP_PATH
 COPY ./poetry.lock ./pyproject.toml /app/
 
 # Project initialization:
 # hadolint ignore=SC2046
-RUN --mount=type=cache,target="$POETRY_CACHE_DIR" \
-  echo "$FLASK_ENV" \
-  && poetry version \
-  # Install deps:
-  && poetry run pip install -U pip \
-  && poetry install \
-    $(if [ "$FLASK_ENV" = 'production' ]; then echo '--only main'; fi) \
-    --no-interaction --no-ansi --sync --no-dev
+RUN poetry install --no-dev
 
 
-# Copy the app code:
-COPY  . .
+# `production` image is used during production / testing
+FROM python-base as production
+ENV FLASK_ENV="production"
+WORKDIR $PYSETUP_PATH
 
-EXPOSE 5000
+# 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 poetry install --no-dev
 
-# Run the app:
+# will become mountpoint of our code
+WORKDIR /app
+
+EXPOSE 5000
 CMD ["poetry", "run", "python", "app.py"]