title: Unable to connect to MongoDB in Spring Boot application
body: <p>I've just created a very basic Spring Boot project using Spring Tool Suite with <code>mongoDB-reactive</code> dependency and run the app but, I keep getting the following exceptions</p>
  
  <blockquote>
    <p>2019-11-27 00:31:19.699  INFO 11988 --- [localhost:27017]
    org.mongodb.driver.cluster               : Exception in monitor thread
    while connecting to server localhost:27017</p>
    
    <p>com.mongodb.MongoSocketOpenException: Exception opening socket    at
    com.mongodb.connection.netty.NettyStream$OpenChannelFutureListener.operationComplete(NettyStream.java:410)
    ~[mongodb-driver-core-3.11.2.jar:na]  at</p>
  </blockquote>
  
  <p>I am using Spring Boot (2.2.1.RELEASE)</p>
  
  <p>Inside <code>applications.properties</code> I've added the following line</p>
  
  <pre><code>spring.data.mongodb.uri=mongodb://localhost:27017/testdb
  </code></pre>
  
  <p>What am I missing?</p>