WebListener.java

package net.johnewart.gearman.server.web;

import com.codahale.metrics.servlets.HealthCheckServlet;
import com.codahale.metrics.servlets.MetricsServlet;
import net.johnewart.gearman.server.config.GearmanServerConfiguration;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.server.handler.ContextHandler;
import org.eclipse.jetty.server.handler.HandlerList;
import org.eclipse.jetty.server.handler.ResourceHandler;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.servlet.http.HttpServlet;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;

public class WebListener {
    private final Logger LOG = LoggerFactory.getLogger(WebListener.class);
    private final static String TEMPLATE_PATH = "net/johnewart/gearman/server/web/templates";
    private final GearmanServerConfiguration serverConfiguration;

    public WebListener(GearmanServerConfiguration serverConfiguration) {
        this.serverConfiguration = serverConfiguration;
    }

    public Map<String, HttpServlet> getServletMappings() {
        final MetricsServlet metricsServlet =
                new MetricsServlet(serverConfiguration.getMetricRegistry());

        final HealthCheckServlet healthCheckServlet =
                new HealthCheckServlet(serverConfiguration.getHealthCheckRegistry());
        final GearmanServlet gearmanServlet =
                new GearmanServlet(serverConfiguration.getJobQueueMonitor(),
                                   serverConfiguration.getJobManager(),
                                   serverConfiguration.getQueueMetrics());
        final DashboardServlet dashboardServlet =
                new DashboardServlet(serverConfiguration.getJobQueueMonitor(),
                                     serverConfiguration.getQueueMetrics());
        final JobQueueServlet jobQueueServlet =
                new JobQueueServlet(serverConfiguration.getJobManager());


        final ClusterServlet clusterServlet = new ClusterServlet(serverConfiguration);
        final ExceptionsServlet exceptionsServlet = new ExceptionsServlet(serverConfiguration.getExceptionStorageEngine());

        Map<String, HttpServlet> mappings = new HashMap<>();

        mappings.put("/gearman/*", gearmanServlet);
        mappings.put("/queues/*", jobQueueServlet);
        mappings.put("/metrics/*", metricsServlet);
        mappings.put("/health/*", healthCheckServlet);
        mappings.put("/cluster/*", clusterServlet);
        mappings.put("/exceptions/*", exceptionsServlet);
        mappings.put("/", dashboardServlet);

        return mappings;
    }

    public void start() throws Exception {
        LOG.info("Listening on " + ":" + serverConfiguration.getHttpPort());

        final Server httpServer = new Server(serverConfiguration.getHttpPort());
        final HandlerList handlerList = new HandlerList();


        final ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        final URL templateURL = classLoader.getResource(TEMPLATE_PATH);
        if (templateURL != null) {
            final String webResourceDir = templateURL.toExternalForm();
            final ResourceHandler resourceHandler = new ResourceHandler();
            final ContextHandler resourceContext = new ContextHandler("/static");
            final ServletContextHandler servletHandler = new ServletContextHandler(
                    ServletContextHandler.SESSIONS);

            resourceHandler.setResourceBase(webResourceDir);
            resourceContext.setHandler(resourceHandler);

            servletHandler.setContextPath("/");
            Map<String, HttpServlet> servletMap = getServletMappings();

            for(Map.Entry<String, HttpServlet> map : servletMap.entrySet()) {
                servletHandler.addServlet(new ServletHolder(map.getValue()), map.getKey());
            }

            handlerList.addHandler(resourceContext);
            handlerList.addHandler(servletHandler);

            httpServer.setHandler(handlerList);
            httpServer.start();
        } else {
            throw new IllegalArgumentException("Template path inaccessible / does not exist.");
        }
    }

}