Visit my.sonatype.com for documentation on Nexus Repository version 2.
Running Nexus Repository 2 Pro in a servlet container or alternative application server is not supported. In fact, you should think of Nexus Repository 2 Pro as an independent server, not as a web application that runs within a servlet container because it's doing much more than a standard web application would ever do. It is interacting with the filesystem and maintaining local caches for hosted and proxy repositories.
We provide a .war version of Nexus Repository 2 Open Source because end-users are responsible for deployments. If your OSS instance running on a Tomcat server is affected by an unknown security vulnerability related to the container, this isn't something we're directly supporting. On the other hand, if a paying customer has an issue with a Nexus Repository 2 Pro server, it is very much our job to jump up and do everything in our ability to support the server.
We've offered professional support for Nexus Repository for years, and we've always striven to strike the right balance between meeting customers' requirements and providing a solid, professional commitment for our products.
We've evaluated a number of containers over the years, and if there was a realistic way for Sonatype to extend support to alternative application servers and servlet containers, we would. In the course of our research and development, we've concluded that to do so would lessen our ability to provide direct support to paying customers.