title: Cannot change port of Vaadin's "second" Tomcat
body: <p>We set up a simple Vaadin project (basically just a copy from Vaadin's initializr) which fails to start on one host where port 8081 is already in use and which cannot be freed up for compliance reasons.</p>
  <p>During start-up, I first see Tomcat being fired up on the port I expect it to be, i.e. the one configured by <code>server.port</code> in the application settings. However, then &quot;another&quot; Tomcat shows up on port 8081:</p>
  <p>(though I suspect it's the same one, just an additional port being opened)
  <a href="https://i.stack.imgur.com/1cPfC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1cPfC.png" alt="enter image description here" /></a></p>
  <p>At first, I suspected this to be related to webpack so I tried changing its config in webpack.config.js<br/>
  <a href="https://i.stack.imgur.com/rbvmI.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rbvmI.png" alt="enter image description here" /></a></p>
  <p>but this didn't do anything at all and the &quot;second&quot; Tomcat still started on 8081 - even with <code>mvn clean &amp;&amp; rm webpack.generated.js</code> before building &amp; starting. I'm clueless about webpack, so maybe I made a mistake here?</p>
  <p>Also considered Vaadin might hold control over that port, with 8081 being the default, so I grep'ed but could not find anything standing out as a good match to me.</p>
  <p>What surprises me most is that I did not find anything at all when searching and this (default port settings conflicting with ports already being in use) simply does not seem to be a problem for anyone else - which seems very odd to me. So I guess I'm just searching for the wrong keywords. Would someone please point me to documentation where this is explained or a similar post elsewhere?</p>