Context docBase

What you can do is the following;

Add a file called ROOT.xml in <catalina_home>/conf/Catalina/localhost/

This ROOT.xml will override the default settings for the root context of the tomcat installation for that engine and host (Catalina and localhost).

Enter the following to the ROOT.xml file;

<Context 
  docBase="<yourApp>" 
  path="" 
  reloadable="true" 
/>

Here, <yourApp> is the name of, well, your app.. :)

And there you go, your application is now the default application and will show up on http://localhost:8080

However, there is one side effect; your application will be loaded twice. Once for localhost:8080 and once for localhost:8080/yourApp. To fix this you can put your application OUTSIDE <catalina_home>/webapps and use a relative or absolute path in the ROOT.xml's docBase tag. Something like this;

<Context 
  docBase="/opt/mywebapps/<yourApp>" 
  path="" 
  reloadable="true" 
/>

And then it should be all OK!