This running without problem:

pip install --no-cache-dir --upgrade -r requirements.txt

But when run it inside Dockerfile it gets that err:

ERROR: Could not find a version that satisfies the requirement cloud-init==20.2 (from versions: none)

This is Dockerfile:

FROM python:3.6

RUN mkdir -p /usr/src/app/server
WORKDIR /user/src/app/server

COPY requirements.txt /usr/src/app/server

RUN python -m pip install --upgrade pip

RUN pip install --no-cache-dir --upgrade -r /usr/src/app/server/requirements.txt

COPY . /usr/src/app/server

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

What could be the problem?