Dockerfile

FROM ubuntu:19.04

ENV DEBIAN_FRONTEND noninteractive
ENV LC_ALL C.UTF-8
ENV LANG C.UTF-8
ENV PYTHONDONTWRITEBYTECODE 1
ENV PIPENV_MAX_SUBPROCESS 64
ENV PIPENV_SKIP_LOCK 1
ENV PIP_EXISTS_ACTION a

# Setup mirrors, for faster downloads (main sources can be slow sometimes).
RUN set -ex && echo 'deb http://mirrors.digitalocean.com/ubuntu/ disco main universe' > /etc/apt/sources.list && \
    echo 'deb http://mirrors.digitalocean.com/ubuntu/ disco-security main universe' >> /etc/apt/sources.list && \
    echo 'deb http://mirrors.digitalocean.com/ubuntu/ disco-updates main universe' >> /etc/apt/sources.list

# -- Install system deps:
RUN set -ex && apt update && apt install python3-dev python3-pip enchant musl-dev libopenblas-dev -y
# -- Install Pipenv:
RUN set -ex && pip3 install pipenv==2018.11.26 --no-cache-dir

# -- Install Application into container:
RUN set -ex && mkdir /opt/pipeline
WORKDIR /opt/pipeline

COPY ./Pipfile /opt/pipeline/Pipfile
COPY ./Pipfile.lock /opt/pipeline/Pipfile.lock

RUN set -ex && mkdir -p /opt/pipeline/python/pipeline/vendor
COPY ./python/pipeline/vendor /opt/pipeline/python/pipeline/vendor

# Install Pipenv deps:
RUN set -ex && pip3 install Cython numpy pytest && pipenv install --system --deploy

# ------------------------
# Multi-Stage Docker Build
# https://docs.docker.com/develop/develop-images/multistage-build/
#
# This enables us to "start fresh", and copy our build artifacts (e.g. python packages),
# without the build depednecies in the final image (e.g. gcc and friends).
# ------------------------
FROM ubuntu:19.04

ENV DEBIAN_FRONTEND noninteractive
ENV LC_ALL C.UTF-8
ENV LANG C.UTF-8
ENV PYTHONDONTWRITEBYTECODE 1

# Setup mirrors, for faster downloads (main sources can be slow sometimes).
RUN echo 'deb http://mirrors.digitalocean.com/ubuntu/ disco main universe' > /etc/apt/sources.list && \
    echo 'deb http://mirrors.digitalocean.com/ubuntu/ disco-security main universe' >> /etc/apt/sources.list && \
    echo 'deb http://mirrors.digitalocean.com/ubuntu/ disco-updates main universe' >> /etc/apt/sources.list

RUN set -ex && apt update && apt install python3 enchant curl pandoc jq git poppler-utils aspell-en -y
RUN set -ex && curl -sL curl -sL https://deb.nodesource.com/setup_10.x | bash - && \
  curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
  echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list && \
  apt-get update -y && apt-get install yarn nodejs -y

# Install nodejs deps
COPY ./package.json /opt/pipeline/package.json
COPY ./yarn.lock /opt/pipeline/yarn.lock
RUN set -ex && yarn install --production

# Copy Python packages from previous build.
COPY --from=0 /usr/local/lib/python3.7/dist-packages/ /usr/local/lib/python3.7/dist-packages/
COPY --from=0 /usr/lib/python3/dist-packages/ /usr/lib/python3/dist-packages/
COPY --from=0 /usr/local/bin/pytest /usr/local/bin/pytest

# Copy
WORKDIR /opt/pipeline
COPY . /opt/pipeline

ARG git_hash
ENV GIT_HASH=$git_hash

CMD ["./pipeline.py"]

Not a fundamental difference but a performance enhancement for when you use it in a project:
Get speedier builds of your code changes by separating out the runtime (Python and node installs and stuff) into a base image that you publish separately and FROM that base image(s) instead.

@SteveShaffer one step ahead!