title: python3 and pip3 in docker
body: <p>I want to use <code>python 3.x</code> and <code>pip3</code> to install some python libraries in docker. I used following commands to do it, but they were not installed.</p>
  
  <pre><code>FROM alpine:latest
  
  RUN apk add python3 py3-pip3 &amp;&amp; \
  pip3 install --upgrade pip3 &amp;&amp; \
  pip3 install wget &amp;&amp;\
  pip3 install sys &amp;&amp;\
  pip3 install threading &amp;&amp;\
  pip3 install time &amp;&amp;\
  pip3 install requests &amp;&amp;\
  pip3 install paho-mqtt &amp;&amp;\
  pip3 install logging &amp;&amp;\
  rm -rf /var/cache/apk/*
  
  COPY NumSide.py /home/mehdi/Download/NumSide.py
  
  CMD ["python3","/home/mehdi/Download/NumSide.py"]
  </code></pre>
  
  <p>Below, the error I got:</p>
  
  <blockquote>
    <p>ERROR: unsatisfiable constraints:   py3-pip3 (missing):   required by:
    world[py3-pip3]   The command '/bin/sh -c apk add python3 py3-pip3 &amp;&amp;
    pip3 install --upgrade pip3 &amp;&amp; pip3 install wget &amp;&amp;pip3 install sys
    &amp;&amp;pip3 install threading &amp;&amp;pip3 install time &amp;&amp;pip3 install requests
    &amp;&amp;pip3 install paho.mqtt.client &amp;&amp;pip3 install logging &amp;&amp;rm -rf
    /var/cache/apk/*' returned a non-zero code: 1</p>
  </blockquote>