How to configure custom servlet in Jruby-rack?

Question

According to Jruby-Rack Github, we can configure to use org.jruby.rack.RackServlet instead of context listener.

Can we use another custom servlet rather than RackServlet? Or can we override org.jruby.rack.RackServlet?

Answer 1

The listener stays - you usually use a servlet instead of a filter with the Servlet API e.g.

<servlet>
  <servlet-name>rack</servlet-name>
  <servlet-class>org.jruby.rack.RackFilter</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>rack</servlet-name>
  <url-pattern>/*</url-pattern>
</servlet-mapping>

<!-- using the above servlet instead of : -->
<!--
<filter>
  <filter-name>RackFilter</filter-name>
  <filter-class>org.jruby.rack.RackFilter</filter-class>
</filter>
<filter-mapping>
  <filter-name>RackFilter</filter-name>
  <url-pattern>/*</url-pattern>
</filter-mapping>
-->

<listener>
  <listener-class>org.jruby.rack.RackServletContextListener</listener-class>
</listener>

You can override the RackFilter as well as the RackServlet you can even use a custom class as long as it plays by JRuby-Rack's rules. With the latest Trinidad (uses JRuby-Rack under the hood) it's a bit easier to configure an alternate servlet without writing a web.xml e.g. in config/trinidad.yml you might :

---
  address: localhost
  port: 3000  # port where Trinidad is running
  rack_servlet:
    class: org.blue-smith.rack.CoolRackServlet

If you do make sure your CoolRackServlet class is on the class-path e.g. package it in a jar and put the .jar under *[APP_ROOT]/lib/java* or for quick testing simply copy the compiled .class file(s) including the package directories under lib/java/classes ...