title: Error "Your requirements.txt is invalid" when following tutorial AWS Elastic Beanstalk's Flask tutorial
body: <p>I'm following AWS Elastic Beanstalk's <a href="http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create-deploy-python-flask.html" rel="nofollow">Flask tutorial</a> to deploy the sample application.</p>
  
  <p>Though I get error <strong>Your requirements.txt is invalid</strong> - in full as below. I <a href="https://www.google.com.vn/?ion=1&amp;espv=2#newwindow=1&amp;q=%22AWS%20Elastic%20Beanstalk%22%20%2B%20flask%20%2B%20tutorial%20%2B%20error%20%2B%20%22Your%20requirements.txt%20is%20invalid%22" rel="nofollow">google</a> for this error though I get no helpful solution for me.</p>
  
  <p>My <strong>requirements.txt</strong> file is pasted in below sections. And I'm using <em>Ubuntu Desktop 16.04</em></p>
  
  <p>As you may succeed the deployment following the tutorial, please share. Thank you.</p>
  
  <h1>Error</h1>
  
  <pre><code>ERROR: Your requirements.txt is invalid. Snapshot your logs for details.
  ERROR: [Instance: i-c78c8f57] Command failed on instance. Return code: 1 Output: (TRUNCATED)...)
    File "/usr/lib64/python2.7/subprocess.py", line 540, in check_call
      raise CalledProcessError(retcode, cmd)
    CalledProcessError:
      Command
      '/opt/python/run/venv/bin/pip install -r /opt/python/ondeck/app/requirements.txt'
      returned non-zero exit status 1.
    Hook /opt/elasticbeanstalk/hooks/appdeploy/pre/03deploy.py failed.
    For more detail, check /var/log/eb-activity.log using console or EB CLI.
  
  INFO: Command execution completed on all instances. Summary: [Successful: 0, Failed: 1].
  WARN: Environment health has transitioned from Pending to Degraded. Command failed on all instances. Initialization completed 45 seconds ago and took 3 minutes.
  ERROR: Create environment operation is complete, but with errors. For more information, see troubleshooting documentation.
  </code></pre>
  
  <h1>requirements.txt</h1>
  
  <pre><code>click==6.6
  Flask==0.11.1
  itsdangerous==0.24
  Jinja2==2.8
  MarkupSafe==0.23
  pkg-resources==0.0.0
  Werkzeug==0.11.10
  </code></pre>