title: gcc' failed with exit status - Python docker integration error
body: <p>I'm new to Python and trying to build a python application with Docker setup. 
  When I try to build my docker (i.e. <code>docker build -t python-barcode</code>), I get the following error</p>
  
  <blockquote>
    <p>error: command 'gcc' failed with exit status 1 (ss: <a href="https://www.screencast.com/t/Do1Bjkbo" rel="nofollow noreferrer">https://www.screencast.com/t/Do1Bjkbo</a>)</p>
  </blockquote>
  
  <p>I tried to install <code>gcc</code>. I couldn't find any packages. Your help is much appreciated. Thanks in advance. </p>
  
  <p>Dockerfile </p>
  
  <pre><code> FROM python:3.6
      # Create app directory
      WORKDIR /app
  
      # Install app dependencies
      COPY src/requirements.txt ./
  
      RUN pip install -r requirements.txt
      RUN pip install zbar
      RUN pip install pyzbar
      # Bundle app source
      COPY src /app
  
      EXPOSE 8080
      CMD [ "python", "ocrApi.py" ]
  </code></pre>
  
  <p><code>requirements.txt</code> file </p>
  
  <pre><code>flask
  Pillow
  pytesseract
  opencv-python
  requests
  </code></pre>
  
  <p><code>ocrApi.py</code> file</p>
  
  <pre><code>from flask import Flask,jsonify,request
  from PIL import Image
  from pyzbar.pyzbar import decode
  import pytesseract
  #import pyzbar.pyzbar as pyzbar
  import cv2
  import io,os
  import requests
  import urllib.request
  import random
  pytesseract.pytesseract.tesseract_cmd = r'C:\Users\chethan\Tesseract-OCR\tesseract'
  ....
  </code></pre>