title: Docker connection error 'Connection broken by NewConnectionError'
body: <p>I am new to docker i just installed it and did some configuration for my django project.
  when i am running <strong><code>docker build .</code></strong> i am getting these error <strong>whats wrong here?</strong></p>
  
  <pre><code>WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('&lt;pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7f1363b604f0&gt;: Failed to establish a new connection: [Errno -3] Try again')': /simple/django/
  </code></pre>
  
  <p><strong>Dockerfile</strong></p>
  
  <pre><code>FROM python:3.8-alpine
  MAINTAINER RAHUL VERMA
  
  ENV PYTHONUNBUFFERED 1
  
  COPY ./requirements.txt /requirements.txt
  RUN pip install -r /requirements.txt
  
  RUN mkdir /app
  WORKDIR app
  COPY ./app /app
  
  RUN adduser -D user
  USER user
  </code></pre>
  
  <p><strong>requirements.txt file</strong></p>
  
  <pre><code>Django==2.2
  djangorestframework==3.11.0
  </code></pre>