Sqlite3 database remains read-only and un-creatable in a Docker container. How to make it writeable?

FROM ubuntu:latest
RUN apt-get -y update
RUN apt-get install -y sqlite3 python python3-pip 
WORKDIR /usr/src/app
COPY . .
RUN pip install -r requirements.txt
ENV PATH="/home/docker/.local/bin:${PATH}"
ENV FLASK_APP=__init__.py
ENV FLASK_DEBUG=1
ENV FLASK_RUN_HOST=0.0.0.0
ENV FLASK_ENV=development 
CMD ["flask", "run"]