title: Using boto3 to update a cloudformation template
body: <p>I am trying to use boto3 to update an existing CloudFormation template, but my code fails on the 'Parameters' property! Here is what I have tried:</p>
  
  <ol>
  <li><p>Read params from a config file</p>
  
  <pre><code>from ConfigParser import SafeConfigParser  
  parser = SafeConfigParser()  
  parser.optionxform=str  
  parser.read( '/parms/SecGrpsParams.cfg')  
  parms = dict(parser.items('params'))
  </code></pre></li>
  </ol>
  
  <p>print parms" produces</p>
  
  <blockquote>
    <p>{'Application': 'Click2Buy', 'AdminCidr': '10.0.0.0/8', 'AppMoniker': 'c2b', 'vId': 'vpc-3bec005f'}</p>
  </blockquote>
  
  <ol start="2">
  <li><p>Call update_stack</p>
  
  <pre><code>client = boto3.client('cloudformation')  
  response = client.update_stack(  
      StackName = args.stackname,  
      TemplateURL = template,  
      Parameters = args.params,  
      Capabilities = ['CAPABILITY_IAM']  
   )
  </code></pre></li>
  <li><p>And the code produces this error:<br>
  botocore.exceptions.ParamValidationError: Parameter validation failed:
  Invalid type for parameter Parameters,<br>
  value: {'Application': 'Click2Buy', 'AdminCidr': '10.0.0.0/8', 'AppMoniker': 'c2b', 'vId': 'vpc-3bec005f'},<br>
  type: type: , valid types: , </p></li>
  </ol>
  
  <p>I have tried to <code>args.params.items()</code>, <code>[args.params]</code>, and <code>[args.params.items()]</code> but can't figure out what is needed.</p>