Tomcat Access valve for populating User Principal from remote header (from Spring Boot)

TomcatCustomizer.java

	@Bean
	public EmbeddedServletContainerCustomizer containerCustomizer() {
		return new EmbeddedServletContainerCustomizer() {
			public void customize(ConfigurableEmbeddedServletContainer factory) {
				if (factory instanceof TomcatEmbeddedServletContainerFactory) {
					TomcatEmbeddedServletContainerFactory containerFactory = (TomcatEmbeddedServletContainerFactory) factory;

					containerFactory.addContextValves(new ValveBase() {
						 @Override
						 public void invoke(Request request, Response response) throws IOException, ServletException {
							 String username = request.getHeader("X-Remote-User");
							 if (username != null) {
								 Principal p = new GenericPrincipal(username, null, null);
								 request.setUserPrincipal(p);
							 }
							 getNext().invoke(request, response);
						 }
					  }
					);
				}
			}
		};
	}