title: Trouble installing opencv in docker container using pip
body: <p>I want to build a python docker container that has scikit-learn, opencv, and numpy. Unfortunately, I couldn't find a pre-built container that contained all these, but I did find the one below that contains numpy and scikit-learn.</p>
  
  <p><a href="https://hub.docker.com/r/frolvlad/alpine-python-machinelearning/" rel="noreferrer">https://hub.docker.com/r/frolvlad/alpine-python-machinelearning/</a></p>
  
  <p>I still needed to install opencv, so within my docker file I included a <code>RUN pip install opencv-python</code>. However, I keep on getting the error below: </p>
  
  <p><code>Could not find a version that satisfies the requirement opencv-python (from version: ) 
  No matching distribution found for opencv-python</code></p>
  
  <p>Every single thing I have read online says that a <code>pip install opencv-python</code> will work, but it isn't working for me for some reason. Is it a problem with the python package maybe?</p>
  
  <p>Any help is appreciated</p>
  
  <p>Also, I will include my full Dockerfile below, I am aiming to use openFaas, which is a serverless framework, so my Dockerfile might look odd: </p>
  
  <pre><code>FROM frolvlad/alpine-python-machinelearning
  
  RUN apk update
  RUN apk upgrade
  
  # Alternatively use ADD https:// (which will not be cached by Docker builder)
  RUN apk --no-cache add curl \
      &amp;&amp; echo "Pulling watchdog binary from Github." \
      &amp;&amp; curl -sSL         
  https://github.com/openfaas/faas/releases/download/0.8.0/fwatchdog &gt; /usr/bin/fwatchdog \
      &amp;&amp; chmod +x /usr/bin/fwatchdog \
      &amp;&amp; apk del curl --no-cache
  
  # Add non root user
  RUN addgroup -S app &amp;&amp; adduser -S -g app app
  RUN chown app /home/app
  
  RUN pip install -U pip
  
  USER app
  
  ENV PATH=$PATH:/home/app/.local/bin
  
  WORKDIR /home/app/
  
  RUN pip install opencv-python
  
  RUN mkdir -p function
  RUN touch ./function/__init__.py
  WORKDIR /home/app/function/
  RUN pip install --user app opencv-python
  
  WORKDIR /home/app/
  COPY function           function
  
  ENV fprocess="python index.py"
  
  HEALTHCHECK --interval=1s CMD [ -e /tmp/.lock ] || exit 1
  
  CMD ["fwatchdog"]
  </code></pre>