ZOOKEEPER-4054: Make prometheus listen host can configure

Make prometheus listen host can configure listen IP, helpful to security. default is 0.0.0.0

Author: shoothzj <shooothzj@gmail.com>

Reviewers: Enrico Olivelli <eolivelli@apache.org>, maoling <maoling@apache.org>

Closes #1574 from Shoothzj/ZOOKEEPER-4054

conf/zoo_sample.cfg

@@ -31,6 +31,7 @@ clientPort=2181
 #
 # https://prometheus.io Metrics Exporter
 #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider
+#metricsProvider.httpHost=0.0.0.0
 #metricsProvider.httpPort=7000
 #metricsProvider.exportJvmInfo=true
 

zookeeper-docs/src/main/resources/markdown/zookeeperAdmin.md

@@ -2119,6 +2119,9 @@ options are used to configure the [AdminServer](#sc_adminserver).
     Set to "org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider" to
     enable Prometheus.io exporter.
 
+* *metricsProvider.httpHost* :
+    **New in 3.8.0:** Prometheus.io exporter will start a Jetty server and listen this address, default is "0.0.0.0"
+  
 * *metricsProvider.httpPort* :
     Prometheus.io exporter will start a Jetty server and bind to this port, it default to 7000.
     Prometheus end point will be http://hostname:httPort/metrics.

zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/main/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProvider.java

@@ -23,6 +23,7 @@ import io.prometheus.client.CollectorRegistry;
 import io.prometheus.client.exporter.MetricsServlet;
 import io.prometheus.client.hotspot.DefaultExports;
 import java.io.IOException;
+import java.net.InetSocketAddress;
 import java.util.Enumeration;
 import java.util.Objects;
 import java.util.Properties;
@@ -63,6 +64,7 @@ public class PrometheusMetricsProvider implements MetricsProvider {
      * </p>
      */
     private final CollectorRegistry collectorRegistry = CollectorRegistry.defaultRegistry;
+    private String host = "0.0.0.0";
     private int port = 7000;
     private boolean exportJvmInfo = true;
     private Server server;
@@ -72,6 +74,7 @@ public class PrometheusMetricsProvider implements MetricsProvider {
     @Override
     public void configure(Properties configuration) throws MetricsProviderLifeCycleException {
         LOG.info("Initializing metrics, configuration: {}", configuration);
+        this.host = configuration.getProperty("httpHost", "0.0.0.0");
         this.port = Integer.parseInt(configuration.getProperty("httpPort", "7000"));
         this.exportJvmInfo = Boolean.parseBoolean(configuration.getProperty("exportJvmInfo", "true"));
     }
@@ -79,11 +82,12 @@ public class PrometheusMetricsProvider implements MetricsProvider {
     @Override
     public void start() throws MetricsProviderLifeCycleException {
         try {
-            LOG.info("Starting /metrics HTTP endpoint at port {} exportJvmInfo: {}", port, exportJvmInfo);
+            LOG.info("Starting /metrics HTTP endpoint at host: {}, port: {}, exportJvmInfo: {}",
+                    host, port, exportJvmInfo);
             if (exportJvmInfo) {
                 DefaultExports.initialize();
             }
-            server = new Server(port);
+            server = new Server(new InetSocketAddress(host, port));
             ServletContextHandler context = new ServletContextHandler();
             context.setContextPath("/");
             server.setHandler(context);

zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/test/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProviderConfigTest.java

@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.zookeeper.metrics.prometheus;
+
+import io.prometheus.client.CollectorRegistry;
+import java.util.Properties;
+import org.apache.zookeeper.metrics.MetricsProviderLifeCycleException;
+import org.junit.Assert;
+import org.junit.Test;
+
+
+public class PrometheusMetricsProviderConfigTest {
+
+    @Test
+    public void testInvalidPort() {
+        Assert.assertThrows(MetricsProviderLifeCycleException.class, () -> {
+            CollectorRegistry.defaultRegistry.clear();
+            PrometheusMetricsProvider provider = new PrometheusMetricsProvider();
+            Properties configuration = new Properties();
+            configuration.setProperty("httpPort", "65536");
+            configuration.setProperty("exportJvmInfo", "false");
+            provider.configure(configuration);
+            provider.start();
+        });
+    }
+
+    @Test
+    public void testInvalidAddr() {
+        Assert.assertThrows(MetricsProviderLifeCycleException.class, () -> {
+            CollectorRegistry.defaultRegistry.clear();
+            PrometheusMetricsProvider provider = new PrometheusMetricsProvider();
+            Properties configuration = new Properties();
+            configuration.setProperty("httpHost", "master");
+            provider.configure(configuration);
+            provider.start();
+        });
+    }
+
+    @Test
+    public void testValidConfig() throws MetricsProviderLifeCycleException {
+        CollectorRegistry.defaultRegistry.clear();
+        PrometheusMetricsProvider provider = new PrometheusMetricsProvider();
+        Properties configuration = new Properties();
+        configuration.setProperty("httpHost", "0.0.0.0");
+        configuration.setProperty("httpPort", "0");
+        provider.configure(configuration);
+        provider.start();
+    }
+
+}

zookeeper-metrics-providers/zookeeper-prometheus-metrics/src/test/java/org/apache/zookeeper/metrics/prometheus/PrometheusMetricsProviderTest.java

@@ -56,6 +56,7 @@ public class PrometheusMetricsProviderTest {
         CollectorRegistry.defaultRegistry.clear();
         provider = new PrometheusMetricsProvider();
         Properties configuration = new Properties();
+        configuration.setProperty("httpHost", "127.0.0.1"); // local host for test
         configuration.setProperty("httpPort", "0"); // ephemeral port
         configuration.setProperty("exportJvmInfo", "false");
         provider.configure(configuration);