[FLUME-2782] Extension-friendly HttpSource

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.6.0, 1.5.2
• Component/s: Sinks+Sources
• Labels: HTTP Source
• Flags: Patch
• External issue URL: https://github.com/apache/flume/pull/18
• Assignee: Unassigned
• Reporter: Luca Rosellini
• Created: 03/Sep/15 07:08
• Updated: 04/Nov/16 10:49

Description

This patch allows third-party to developers extend HttpSource behavior easily, without having to reimplement the whole thing.

More specifically:

• Adds an hook to customize org.mortbay.jetty.servlet.Context.
• Delegates the HttpServlet instance creation to a protected factory method.
• Changes FlumeHttpServlet visibility to protected, to let third party developers extend from it.
• Adds an hook in FlumeHTTPServlet to customize HttpServletResponse before it is flushed.

We developed this patch because we had to add a custom servlet filter to the Jetty context.

Having this patch applied, a third-party developer could easily extend HttpSource like this:

CustomHTTPSource.java

public class CustomHTTPSource extends HTTPSource {

    @Override
    protected void customizeServletContext(Context context) {
        super.customizeServletContext(context);

        context.addFilter(MyCustomHttpServletFilter.class,"/*",0);
    }

    @Override
    protected HttpServlet getServlet() {
        return new KeedioFlumeHTTPServlet();
    }

    protected class KeedioFlumeHTTPServlet extends FlumeHTTPServlet{
        @Override
        protected void customizeServletResponse(HttpServletRequest request, HttpServletResponse response) {
            super.customizeServletResponse(request, response);

            response.addHeader("Accept-Encoding","...");
        }
    }
}