title: Issue with Elastic Beanstalk, Immutable Deployments, and CloudFormation
body: <p>We have just recently begun using immutable deployments with Elastic Beanstalk. To be more specific, we enabled</p>
  <ul>
  <li>immutable application deployment and</li>
  <li>immutable configuration updates.</li>
  </ul>
  <p>We use CloudFormation for everything. E.g., instead of enabling immutable deployments using the UI (AWS Management Console), we added the respective <code>OptionSettings</code> to the <code>ConfigurationTemplate</code> within our configuration template.</p>
  <p>However, we ran into some issues using this approach. Whenever we change certain properties within the <code>ConfigurationTemplate</code>, we get this error message:</p>
  <blockquote>
  <p>Failed to deploy application.</p>
  <p>Cannot update resource configuration and instance configuration simultaneously with immutable deployments. Choose a different deployment policy and redeploy to make this change.</p>
  </blockquote>
  <p>After intensively searching the documentation, we were not able to find out exactly <em>what</em> changes we may do with immutable deployments, and what causes the above error. We got the error when we tried to manipulate the following <code>OptionSettings</code> property:</p>
  <pre><code>- Namespace: 'aws:autoscaling:asg'
    OptionName: MinSize
    Value: 6
  - Namespace: 'aws:autoscaling:asg'
    OptionName: MaxSize
    Value: 6
  </code></pre>
  <p>We would be very thankful for anyone who could tip us off in regards to <em>what</em> options we might change within our CloudFormation template without causing the deployment to fail. Thank you so much!</p>