Update Dockerfile

docker/Dockerfile

@@ -1,31 +1,30 @@
-ARG BASE_IMAGE=ubuntu:18.04
+ARG BASE_IMAGE=python:3.9-slim
 FROM $BASE_IMAGE
 LABEL maintainer="NeuML"
 LABEL repository="paperai"
 
-# Argument for ENTRYPOINT
-ARG START=/bin/bash
-ENV START=${START}
+# Set Python version (i.e. 3, 3.9)
+ARG PYTHON_VERSION=3
 
 # Locale environment variables
 ENV LC_ALL=C.UTF-8
 ENV LANG=C.UTF-8
 
 # Install required packages
 RUN apt-get update && \
-    apt-get -y --no-install-recommends install libgomp1 gcc g++ python3.7 python3.7-dev python3-pip wget && \
+    apt-get -y --no-install-recommends install libgomp1 gcc g++ python${PYTHON_VERSION} python${PYTHON_VERSION}-dev python3-pip wget && \
     rm -rf /var/lib/apt/lists
 
 # Install paperai project and dependencies
-RUN ln -sf /usr/bin/python3.7 /usr/bin/python && \
+RUN ln -sf /usr/bin/python${PYTHON_VERSION} /usr/bin/python && \
     python -m pip install --no-cache-dir -U pip wheel setuptools && \
     python -m pip install --no-cache-dir paperai
 
 # Cleanup build packages
-RUN apt-get -y purge gcc g++ python3-dev && apt-get -y autoremove
+RUN apt-get -y purge gcc g++ python${PYTHON_VERSION}-dev && apt-get -y autoremove
 
 # Create paperetl directories
 RUN mkdir -p paperetl/data paperetl/report
 
 # Start script
-ENTRYPOINT ${START}
+ENTRYPOINT ["/bin/bash"]