An example of using Undertow ResponseHeader filters with WildFly Swarm

Main.java

import org.jboss.shrinkwrap.api.ShrinkWrap;
import org.wildfly.swarm.config.undertow.FilterConfiguration;
import org.wildfly.swarm.config.undertow.configuration.ResponseHeader;
import org.wildfly.swarm.config.undertow.server.host.FilterRef;
import org.wildfly.swarm.container.Container;
import org.wildfly.swarm.undertow.UndertowFraction;
import org.wildfly.swarm.undertow.WARArchive;

public class Main {
    public static void main(String... args) throws Exception {
        Container container = new Container();

        // Create a ResponseHeader identified by a key with the desired HTTP
        // header name and value
        ResponseHeader responseHeader = new ResponseHeader("foo-header")
                .headerName("foo")
                .headerValue("bar");

        // Create a FilterRef referencing the response header's key. The
        // predicate is optional to restrict the application of this filter
        // to specific requests.
        // http://undertow.io/undertow-docs/undertow-docs-1.2.0/predicates-attributes-handlers.html
        FilterRef filterRef = new FilterRef("foo-header")
                .predicate("path-suffix['.html'] or path-prefix['/js']");

        // Modify the default UndertowFraction to include our ResponseHeader
        UndertowFraction fraction = UndertowFraction.createDefaultFraction()
                .filterConfiguration(new FilterConfiguration()
                        .responseHeader(responseHeader));

        // Modify the default host of the default server to use our FilterRef
        fraction.subresources().server("default-server").subresources()
                .host("default-host").filterRef(filterRef);

        // Tell the Container to use our customized UndertowFraction
        container.fraction(fraction);

        // Your application may have different code below to finish
        // configuring and booting WildFly Swarm
        container.start();
        WARArchive war = ShrinkWrap.create(WARArchive.class);
        war.staticContent();
        war.addAllDependencies();
        container.deploy(war);
    }
}