Global custom filter in Apache Tomcat

We are aware about custom filters and built in filters available in Apache Tomcat.
If we are writing a custom java filter in our project, it will be look like follows,

@WebFilter("/*")
public class MyFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, 
                         FilterChain chain) throws IOException, ServletException {

        HttpServletResponse httpResponse = (HttpServletResponse) response;
        //your custom filter or set custom response header here
        chain.doFilter(request, response);
    }
}

This custom filter can help us to track and filter all requests coming to our webappliation, but it can not act like a global filter for all webapplications hosted in Apache Tomcat.

Apache Tomcat supports custom Valve elements which can help us to make this happen.

A Valve element represents a component that will be inserted into the request processing pipeline for the associated Catalina container (Engine, Host, or Context)

Following are the steps to implement a custom Valve in Apache Tomcat:

1. Create a Maven Java Application.
2. Add the following dependency:

<!-- https://mvnrepository.com/artifact/org.apache.tomcat/catalina --><dependency>    <groupId>org.apache.tomcat</groupId>    <artifactId>catalina</artifactId>    <version>6.0.53</version>    <scope>provided</scope></dependency>

3. Create your Java class and extend it from ValveBase.
4. Implement the invoke(Request, Response) method.

5. import org.apache.catalina.valves.ValveBase;
   
   public class GlobalFilterValve extends ValveBase {
   
       @Override
       public void invoke(Request request, Response response) throws IOException, ServletException {
           //Do your filter/setting header in response here
           getNext().invoke(request, response);
       }
   
   }

6. Build your library (.jar) file
7. Copy the jar file in the ${tomcat.home}/lib directory.
8. Configure the server.xml to use your new valve. For example:

<valve className="org.devan.MyValve"/>

8. Start the server to see your new valve in action

Thank you !!!