I am trying to create an image to run api(fastapi) in docker and the software that i am using in api requires ubuntu 16.04 while I am trying to install python packages I am getting "No matching distribution found for fastapi " error while other packages are being correctly installed. Here is my Docker file code

FROM ubuntu:16.04
LABEL maintainer="sai"

COPY ./app /api/api
COPY requirements.txt ./requirements.txt
RUN apt-get update \
    && apt install python3-pip -y \
    && pip3 install --upgrade pip==20.0.1 \
    && pip install -r requirements.txt
    
RUN apt-get update && \
    apt-get install -y --no-install-recommends \
        g++ \
        make \
        automake \
        autoconf \
        bzip2 \
        unzip \
        wget \
        sox \
        libtool \
        git \
        subversion \
        python2.7 \
        python3 \
        zlib1g-dev \
        gfortran \
        ca-certificates \
        patch \
        ffmpeg \
    vim && \
    rm -rf /var/lib/apt/lists/*

RUN ln -s /usr/bin/python2.7 /usr/bin/python
 
#other toolkit installation commands     

ENV PYTHONPATH=/api
WORKDIR /api

EXPOSE 8000

ENTRYPOINT ["uvicorn"]
CMD ["api.main:app", "--host", "0.0.0.0"]

I am new to docker so excuse me for my mistakes. I have a working api i need to dockerize it also the api involves creating and deleting file and folders is this ok with Docker?

Note I also tried upgrading pip to latest version but didn't work any pointers to further helpful resources in dockerizing the api are most welcome