Improved Docker image size

Improved Docker image size by using python's alpine image and installing the required dependencies seperately. 
This reduces the size of the image from 1.46 GB to 0.982 GB

Dockerfile

@@ -5,19 +5,20 @@ COPY ./static/package*.json /code/static/
 RUN cd /code/static && npm install
 
 # Main image
-FROM python:3.7
+FROM python:3.7-alpine
 
-# install poetry, "pip3 install poetry==1.1.5" doesn't work
-# poetry will be available at /root/.poetry/bin/poetry
-RUN curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python -
+# install poetry
+RUN apk update \
+    && apk add --no-cache build-base openssl-dev libffi-dev \
+    && pip3 install poetry 
 
 WORKDIR /code
 
 # install dependencies
 COPY poetry.lock pyproject.toml ./
 
-RUN /root/.poetry/bin/poetry config virtualenvs.create false \
-  && /root/.poetry/bin/poetry install --no-root
+RUN poetry config virtualenvs.create false \
+  && poetry install --no-root
 
 # copy npm packages
 COPY --from=npm /code /code