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How can we use opencv in a multistage docker image?

I recently learned about the concept of building docker images based on a multi-staged Dockerfile.
I have been trying simple examples of multi-staged Dockerfiles, and they were working fine. However, when I tried implementing the concept for my own application, I was facing some issues.
My application is about object detection in videos, so I use python and Tensorflow.
Here is my Dockerfile:
FROM python:3-slim AS base
WORKDIR /objectDetector
COPY detect_objects.py .
COPY detector.py .
COPY requirements.txt .
ADD data /objectDetector/data/
ADD models /objectDetector/models/
RUN apt-get update && \
apt-get install protobuf-compiler -y && \
apt-get install ffmpeg libsm6 libxext6 -y && \
apt-get install gcc -y
RUN pip3 install update && python3 -m pip install --upgrade pip
RUN pip3 install tensorflow-cpu==2.9.1
RUN pip3 install opencv-python==4.6.0.66
RUN pip3 install opencv-contrib-python
WORKDIR /objectDetector/models/research
RUN protoc object_detection/protos/*.proto --python_out=.
RUN cp object_detection/packages/tf2/setup.py .
RUN python -m pip install .
RUN python object_detection/builders/model_builder_tf2_test.py
WORKDIR /objectDetector/models/research
RUN pip3 install wheel && pip3 wheel . --wheel-dir=./wheels
FROM python:3-slim
RUN pip3 install update && python3 -m pip install --upgrade pip
COPY --from=base /objectDetector /objectDetector
WORKDIR /objectDetector
RUN pip3 install --no-index --find-links=/objectDetector/models/research/wheels -r requirements.txt
When I try to run my application in the final stage of the container, I receive the following error:
root#3f062f9a5d64:/objectDetector# python detect_objects.py
Traceback (most recent call last):
File "/objectDetector/detect_objects.py", line 3, in <module>
import cv2
ModuleNotFoundError: No module named 'cv2'
So per my understanding, it seems that opencv-python is not successfully moved from the 1st stage to the 2nd.
I have been searching around, and I found some good blogs and questions tackling the issue of multi-staging Dockerfiles, specifically for python libraries. However, it seems I missing something here.
Here are some references that I have been following to solve the issue:
How do I reduce a python (docker) image size using a multi-stage build?
Multi-stage build usage for cuda,cudnn,opencv and ffmpeg #806
So my question is: How can we use opencv in a multistage docker image?

aws eb opencv-python "web: from .cv2 import"

in aws-eb I am deployed an application -django- and there was no error on that process. Health is green and OK but page is giving Internal Server Error. so I checked the logs and saw the below error.
... web: from .cv2 import
... web: ImportError: libGL.so.1: cannot open shared object file: No such file or directory
while installing requirements.txt on deployment process opencv must be installed. because it includes opencv-python==4.5.5.64
so I not quite sure what is the above error pointing at.
and helpers.py this is how I am import it.
import requests
import cv2

libGL.so is installed with the package libgl1, pip3 install opencv-python is not sufficient here.
Connect the aws via ssh and run;
apt-get update && apt-get install libgl1
Or even better, consider using docker containers for the project and add the installation commands to the Dockerfile.
Also, as https://stackoverflow.com/a/66473309/12416058 suggests, Package python3-opencv includes all system dependencies of OpenCV. so installing it may prevent further errors.
To install python3-opencv;
apt-get update && apt-get install -y python3-opencv
pip install -r requirements.txt
To install in Dockerfile:
RUN apt-get update && apt-get install -y python3-opencv
RUN pip install -r requirements.txt

docker image build fails at RUN pip install -r requirements.txt in a Flask app

I have a Flask application with the following requirements.txt
chalice
matplotlib
sklearn
numpy
scipy
pandas
flask
flask_restful
and the following Dockerfile:
FROM python:3.6.1-alpine
WORKDIR /project
ADD . /project
RUN pip install -r requirements.txt
CMD ["python","app.py"]
Running the command docker image build -t clf_test .
generates the following error:
You are using pip version 9.0.1, however version 20.2.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
The command '/bin/sh -c pip install -r requirements.txt' returned a non-zero code: 1
It seems that the matplotlib can't get installed for some reason.
Running the pip install -r requirements.txt locally doesn't produce any errors

matplotlib must be built from source, and compiling it requires a number of supporting libraries as well as a functioning C compiler. You can figure out what these are and install them so that it builds properly...
...or you can just base your Dockerfile on the non-alpine python:3.6.1 image and then apt-get install python3-matplotlib before installing your other requirements. E.g., this builds without errors:
FROM python:3.6.1
WORKDIR /project
ADD . /project
RUN apt update; apt-get -y install python3-matplotlib
RUN pip install -r requirements.txt
CMD ["python","app.py"]

problem install pika (rabbitmq sdk in python ) in docker _ no module named 'pika'

I am trying to install rabbitmq (pika) driver in my python container, but in local deployment, there is no problem.
FROM ubuntu:20.04
WORKDIR /usr/src/app
COPY requirements.txt ./
RUN apt-get update && apt-get -y install gcc python3.7 python3-pip
RUN pip3 install --upgrade pip
RUN pip3 install -r requirements.txt
COPY . .
CMD ["python","index.py"]
this is my requerments.txt file :
requests
telethon
Flask
flask-mongoengine
Flask_JWT_Extended
Flask_Bcrypt
flask-restful
flask-cors
jsonschema
werkzeug
pandas
xlrd
Kanpai
pika
Flask-APScheduler
docker build steps complete with no error and install all the dependencies with no error but when I try to run my container it crashes with this error :
no module named 'pika'

installing python3.7 will not work here, you are still using python3.8 by using pip3 command and your CMD will also start python3.8, I suggest you to use python:3.7 base image
so try this:
FROM python:3.7
WORKDIR /usr/src/app
COPY requirements.txt ./
RUN apt-get update && apt-get -y install gcc
RUN pip install --upgrade pip
RUN pip install -r requirements.txt
COPY . .
CMD ["python","index.py"]

pip install error while building docker images

I'm using centos/python-36-centos7 as a base image of my application. In Dockerfile, after RUN pip install --upgrade pip, pip successfully upgrades from 9.0.1 to 18.0. Next step, at RUN pip install --no-cache-dir -r requirements.txt, docker keeps throwing error:
/bin/sh: /opt/app-root/bin/pip: /opt/app-root/bin/python3: bad interpreter: No such file or directory
The command '/bin/sh -c pip install --no-cache-dir -r requirements.txt' returned a non-zero code: 126
Operating systems: CentOS 7.2 64 bit
Docker version:18.06.0-ce, build 0ffa825
Complete Dockerfile:
FROM centos/python-36-centos7
MAINTAINER SamYu,sam_miaoyu#foxmail.com
USER root
ENV TZ=Asia/Shanghai
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone
COPY . /faceDetectBaseImg
COPY ./pip.conf /etc/pip.conf
WORKDIR /faceDetectBaseImg
RUN yum install -y epel-release
RUN rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7
RUN rpm --import http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro
RUN rpm -Uvh http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-1.el7.nux.noarch.rpm
RUN yum install -y ffmpeg
RUN yum -y install libXrender
RUN pip install --upgrade pip
RUN pip install --no-cache-dir -r requirements.txt
pip.conf:
[global]
trusted-host = mirrors.aliyun.com
index-url = https://mirrors.aliyun.com/pypi/simple
UPDATES:
problem fixed by removing pip install --upgrade pip and running pip 9.0.1. I am thinking it has something to do with pip 18.0 vs CentOS7 docker images. I would still like to know if there is a fix under pip 18.0.

Problems fixed completely by pulling centOS7 image and build python from source. As a reminder, don't use the latest version of centos/python-36-centos7 as of June 2018.