Following the wiki suggestions about the best way of installing obspy, I ended up changing my application and I’m now running obspy inside an Anaconda container. It works fine this way. I attach here the Dockerfile I’m using, in case it can be useful for someone else
FROM continuumio/miniconda3
RUN mkdir src
WORKDIR src/
COPY . .
RUN /bin/bash && \
conda config --add channels conda-forge && \
conda init bash && \
. ~/.bashrc && \
conda create -n obspy python=3.7 && \
conda activate obspy
RUN conda install obspy
CMD ["python3", "client.py"]