ternal MongoDB services.
You use the <a href=/v1.18/docs/examples/bookinfo/>Istio Bookinfo sample application</a>, the version in which the book
ratings data is persisted in a MongoDB database. You deploy this database outside the cluster and configure the
<em>ratings</em> microservice to use it. You will learn multiple options of controlling traffic to external MongoDB services and their
pros and cons.</p><h2 id=bookinfo-with-external-ratings-database>Bookinfo with external ratings database</h2><p>First, y