####################
# Dependancy Builder
####################
FROM python:3.7-stretch AS builder

# Set working directory
WORKDIR /usr/src/app

# Turns off writing .pyc files; superfluous on an ephemeral container.
ENV PYTHONDONTWRITEBYTECODE=1
# Seems to speed things up
ENV PYTHONUNBUFFERED=1

# Use the executables from the virtualenv instead of globals
ENV PATH="/opt/venv/bin:$PATH"

# Setup virtualenv to build dependancies into
RUN python -m venv /opt/venv

# Install python dependancies
COPY requirements.txt ./requirements.txt
RUN pip install --no-cache-dir -r requirements.txt

#####################
# Condensed App Image
#####################

# Smaller official Debian-based Python image
FROM python:3.7-slim-stretch AS app

# Set working directory
WORKDIR /usr/src/app

# Extra python env
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1
ENV PIP_DISABLE_PIP_VERSION_CHECK=1
ENV PATH="/opt/venv/bin:$PATH"

# Setup the virtualenv
RUN python -m venv /opt/venv

# Copy in tools and python environment
COPY --from=builder /opt/venv /opt/venv

# Copy in the rest of the app
COPY ./ /usr/src/app