gure 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, you set up a MongoDB database instance to hold book ratings data outside of your Kubernetes cluster. Then you
modify the <a href=/v1.15/docs/examples/bookinfo/>Bookinfo sample application</a> to use your database.</p><h3 id=setting-up-the-ratings-da