Instrumenting Web Applications

The metrics-servlet module provides a Servlet filter which has meters for status codes, a counter for the number of active requests, and a timer for request duration. You can use it in your web.xml like this:

<filter>
    <filter-name>instrumentedFilter</filter-name>
    <filter-class>com.codahale.metrics.servlet.InstrumentedFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>instrumentedFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

You will need to add your MetricRegistry to the servlet context as an attribute named com.codahale.metrics.servlet.InstrumentedFilter.registry. You can do this using the Servlet API by extending InstrumentedFilterContextListener:

public class MyInstrumentedFilterContextListener extends InstrumentedFilterContextListener {
    public static final MetricRegistry REGISTRY = new MetricRegistry();

    @Override
    protected MetricRegistry getMetricRegistry() {
        return REGISTRY;
    }
}