com.codahale.metrics.servlets.AdminServlet Maven / Gradle / Ivy

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package com.codahale.metrics.servlets;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.MessageFormat;

public class AdminServlet extends HttpServlet {
    public static final String DEFAULT_HEALTHCHECK_URI = "/healthcheck";
    public static final String DEFAULT_METRICS_URI = "/metrics";
    public static final String DEFAULT_PING_URI = "/ping";
    public static final String DEFAULT_THREADS_URI = "/threads";
    private static final String TEMPLATE = "\n" +
            "\n" +
            "\n" +
            "  Metrics{8}\n" +
            "\n" +
            "\n" +
            "  Operational Menu{8}\n" +
            "  \n" +
            "    Metrics\n" +
            "    Ping\n" +
            "    Threads\n" +
            "    Healthcheck\n" +
            "  \n" +
            "\n" +
            "";
    private static final String CONTENT_TYPE = "text/html";
    private static final long serialVersionUID = -2850794040708785318L;

    private transient HealthCheckServlet healthCheckServlet;
    private transient MetricsServlet metricsServlet;
    private transient PingServlet pingServlet;
    private transient ThreadDumpServlet threadDumpServlet;
    private transient String metricsUri;
    private transient String pingUri;
    private transient String threadsUri;
    private transient String healthcheckUri;
    private transient String serviceName;

    @Override
    public void init(ServletConfig config) throws ServletException {
        this.healthCheckServlet = new HealthCheckServlet();
        healthCheckServlet.init(config);

        this.metricsServlet = new MetricsServlet();
        metricsServlet.init(config);

        this.pingServlet = new PingServlet();
        pingServlet.init(config);

        this.threadDumpServlet = new ThreadDumpServlet();
        threadDumpServlet.init(config);

        this.metricsUri = getParam(config.getInitParameter("metrics-uri"), DEFAULT_METRICS_URI);
        this.pingUri = getParam(config.getInitParameter("ping-uri"), DEFAULT_PING_URI);
        this.threadsUri = getParam(config.getInitParameter("threads-uri"), DEFAULT_THREADS_URI);
        this.healthcheckUri = getParam(config.getInitParameter("healthcheck-uri"), DEFAULT_HEALTHCHECK_URI);
        this.serviceName = getParam(config.getInitParameter("service-name"), null);
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        final String path = req.getContextPath() + req.getServletPath();

        resp.setStatus(HttpServletResponse.SC_OK);
        resp.setHeader("Cache-Control", "must-revalidate,no-cache,no-store");
        resp.setContentType(CONTENT_TYPE);
        final PrintWriter writer = resp.getWriter();
        try {
            writer.println(MessageFormat.format(TEMPLATE, path, metricsUri, path, pingUri, path,
                                                threadsUri, path, healthcheckUri,
                                                serviceName == null ? "" : " (" + serviceName + ")"));
        } finally {
            writer.close();
        }
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        final String uri = req.getPathInfo();
        if (uri == null || uri.equals("/")) {
            super.service(req, resp);
        } else if (uri.equals(healthcheckUri)) {
            healthCheckServlet.service(req, resp);
        } else if (uri.startsWith(metricsUri)) {
            metricsServlet.service(req, resp);
        } else if (uri.equals(pingUri)) {
            pingServlet.service(req, resp);
        } else if (uri.equals(threadsUri)) {
            threadDumpServlet.service(req, resp);
        } else {
            resp.sendError(HttpServletResponse.SC_NOT_FOUND);
        }
    }

    private static String getParam(String initParam, String defaultValue) {
        return initParam == null ? defaultValue : initParam;
    }
}