Marvel: Add dedicated settings service

This commit adds a dedicated MarvelSettingsService to centralized all Marvel settings.

Original commit: elastic/x-pack-elasticsearch@f7b97be396

marvel/src/main/java/org/elasticsearch/marvel/MarvelModule.java

@@ -8,22 +8,22 @@ package org.elasticsearch.marvel;
 import com.google.common.collect.ImmutableList;
 import org.elasticsearch.common.inject.AbstractModule;
 import org.elasticsearch.common.inject.Module;
-import org.elasticsearch.common.inject.Scopes;
 import org.elasticsearch.common.inject.SpawnModules;
 import org.elasticsearch.marvel.agent.AgentService;
 import org.elasticsearch.marvel.agent.collector.CollectorModule;
 import org.elasticsearch.marvel.agent.exporter.ExporterModule;
+import org.elasticsearch.marvel.agent.settings.MarvelSettingsModule;
 import org.elasticsearch.marvel.license.LicenseModule;
 
 public class MarvelModule extends AbstractModule implements SpawnModules {
 
     @Override
     protected void configure() {
-        bind(AgentService.class).in(Scopes.SINGLETON);
+        bind(AgentService.class).asEagerSingleton();
     }
 
     @Override
     public Iterable<? extends Module> spawnModules() {
-        return ImmutableList.of(new LicenseModule(), new CollectorModule(), new ExporterModule());
+        return ImmutableList.of(new MarvelSettingsModule(), new LicenseModule(), new CollectorModule(), new ExporterModule());
     }
 }

marvel/src/main/java/org/elasticsearch/marvel/agent/AgentService.java

@@ -8,7 +8,6 @@ package org.elasticsearch.marvel.agent;
 import com.google.common.collect.ImmutableSet;
 import org.elasticsearch.cluster.settings.ClusterDynamicSettings;
 import org.elasticsearch.cluster.settings.DynamicSettings;
-import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
@@ -28,19 +27,15 @@ public class AgentService extends AbstractLifecycleComponent<AgentService> imple
     private static final String SETTINGS_BASE = "marvel.agent.";
 
     public static final String SETTINGS_INTERVAL = SETTINGS_BASE + "interval";
-    public static final String SETTINGS_INDICES = SETTINGS_BASE + "indices";
     public static final String SETTINGS_ENABLED = SETTINGS_BASE + "enabled";
 
     public static final String SETTINGS_STATS_TIMEOUT = SETTINGS_BASE + "stats.timeout";
-    public static final String SETTINGS_INDICES_STATS_TIMEOUT = SETTINGS_BASE + "stats.indices.timeout";
 
     private volatile ExportingWorker exportingWorker;
 
     private volatile Thread workerThread;
     private volatile long samplingInterval;
-    volatile private String[] indicesToExport = Strings.EMPTY_ARRAY;
 
-    private volatile TimeValue indicesStatsTimeout;
     private volatile TimeValue clusterStatsTimeout;
 
     private final Collection<Collector> collectors;
@@ -53,10 +48,8 @@ public class AgentService extends AbstractLifecycleComponent<AgentService> imple
                         Set<Collector> collectors, Set<Exporter> exporters) {
         super(settings);
         this.samplingInterval = settings.getAsTime(SETTINGS_INTERVAL, TimeValue.timeValueSeconds(10)).millis();
-        this.indicesToExport = settings.getAsArray(SETTINGS_INDICES, this.indicesToExport, true);
 
         TimeValue statsTimeout = settings.getAsTime(SETTINGS_STATS_TIMEOUT, TimeValue.timeValueMinutes(10));
-        indicesStatsTimeout = settings.getAsTime(SETTINGS_INDICES_STATS_TIMEOUT, statsTimeout);
 
         if (settings.getAsBoolean(SETTINGS_ENABLED, true)) {
             this.collectors = ImmutableSet.copyOf(collectors);
@@ -69,9 +62,7 @@ public class AgentService extends AbstractLifecycleComponent<AgentService> imple
 
         nodeSettingsService.addListener(this);
         dynamicSettings.addDynamicSetting(SETTINGS_INTERVAL);
-        dynamicSettings.addDynamicSetting(SETTINGS_INDICES + ".*"); // array settings
         dynamicSettings.addDynamicSetting(SETTINGS_STATS_TIMEOUT);
-        dynamicSettings.addDynamicSetting(SETTINGS_INDICES_STATS_TIMEOUT);
 
         logger.trace("marvel is running in [{}] mode", licenseService.mode());
     }
@@ -163,20 +154,6 @@ public class AgentService extends AbstractLifecycleComponent<AgentService> imple
             samplingInterval = newSamplingInterval.millis();
             applyIntervalSettings();
         }
-
-        String[] indices = settings.getAsArray(SETTINGS_INDICES, null, true);
-        if (indices != null) {
-            logger.info("sampling indices updated to [{}]", Strings.arrayToCommaDelimitedString(indices));
-            indicesToExport = indices;
-        }
-
-        TimeValue statsTimeout = settings.getAsTime(SETTINGS_STATS_TIMEOUT, TimeValue.timeValueMinutes(10));
-        TimeValue newTimeValue = settings.getAsTime(SETTINGS_INDICES_STATS_TIMEOUT, statsTimeout);
-        if (!indicesStatsTimeout.equals(newTimeValue)) {
-            logger.info("indices stats timeout updated to [{}]", newTimeValue);
-            indicesStatsTimeout = newTimeValue;
-
-        }
     }
 
     class ExportingWorker implements Runnable {

marvel/src/main/java/org/elasticsearch/marvel/agent/collector/indices/IndexStatsCollector.java

@@ -15,12 +15,13 @@ import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.marvel.agent.collector.AbstractCollector;
 import org.elasticsearch.marvel.agent.exporter.MarvelDoc;
+import org.elasticsearch.marvel.agent.settings.MarvelSettingsService;
 
 import java.util.Collection;
 
 /**
  * Collector for indices statistics.
- *
+ * <p/>
  * This collector runs on the master node only and collect a {@link IndexStatsMarvelDoc} document
  * for each existing index in the cluster.
  */
@@ -31,12 +32,14 @@ public class IndexStatsCollector extends AbstractCollector<IndexStatsCollector>
 
     private final ClusterName clusterName;
     private final Client client;
+    private final MarvelSettingsService marvelSettings;
 
     @Inject
-    public IndexStatsCollector(Settings settings, ClusterService clusterService, ClusterName clusterName, Client client) {
+    public IndexStatsCollector(Settings settings, ClusterService clusterService, ClusterName clusterName, Client client, MarvelSettingsService marvelSettings) {
         super(settings, NAME, clusterService);
         this.client = client;
         this.clusterName = clusterName;
+        this.marvelSettings = marvelSettings;
     }
 
     @Override
@@ -48,11 +51,12 @@ public class IndexStatsCollector extends AbstractCollector<IndexStatsCollector>
     protected Collection<MarvelDoc> doCollect() throws Exception {
         ImmutableList.Builder<MarvelDoc> results = ImmutableList.builder();
 
-        IndicesStatsResponse indicesStats = client.admin().indices().prepareStats().all()
+        IndicesStatsResponse indicesStats = client.admin().indices().prepareStats()
                 .setStore(true)
                 .setIndexing(true)
                 .setDocs(true)
-                .get();
+                .setIndices(marvelSettings.indices())
+                .get(marvelSettings.indexStatsTimeout());
 
         long timestamp = System.currentTimeMillis();
         for (IndexStats indexStats : indicesStats.getIndices().values()) {

marvel/src/main/java/org/elasticsearch/marvel/agent/settings/MarvelSetting.java

@@ -0,0 +1,209 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.marvel.agent.settings;
+
+import org.elasticsearch.ElasticsearchParseException;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.unit.TimeValue;
+
+public abstract class MarvelSetting<V> {
+
+    private final String name;
+    private final String description;
+    private final V defaultValue;
+
+    private volatile V value;
+
+    MarvelSetting(String name, String description, V defaultValue) {
+        this.name = name;
+        this.description = description;
+        this.defaultValue = defaultValue;
+    }
+
+    abstract boolean onInit(Settings settings);
+
+    abstract boolean onRefresh(Settings settings);
+
+    public String getName() {
+        return name;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public V getDefaultValue() {
+        return defaultValue;
+    }
+
+    public V getValue() {
+        return value;
+    }
+
+    public void setValue(V value) {
+        this.value = value;
+    }
+
+    public String getValueAsString() {
+        return getValue() != null ? getValue().toString() : "null";
+    }
+
+    public boolean isDynamic() {
+        return true;
+    }
+
+    public String dynamicSettingName() {
+        return getName();
+    }
+
+    public static BooleanSetting booleanSetting(String name, Boolean defaultValue, String description) {
+        return new BooleanSetting(name, description, defaultValue);
+    }
+
+    public static StringSetting stringSetting(String name, String defaultValue, String description) {
+        return new StringSetting(name, description, defaultValue);
+    }
+
+    public static StringArraySetting arraySetting(String name, String[] defaultValue, String description) {
+        return new StringArraySetting(name, description, defaultValue);
+    }
+
+    public static TimeValueSetting timeSetting(String name, TimeValue defaultValue, String description) {
+        return new TimeValueSetting(name, description, defaultValue);
+    }
+
+    static class BooleanSetting extends MarvelSetting<Boolean> {
+
+        BooleanSetting(String name, String description, Boolean defaultValue) {
+            super(name, description, defaultValue);
+        }
+
+        @Override
+        boolean onInit(Settings settings) {
+            setValue(settings.getAsBoolean(getName(), getDefaultValue()));
+            return true;
+        }
+
+        @Override
+        boolean onRefresh(Settings settings) {
+            Boolean updated = settings.getAsBoolean(getName(), null);
+            if ((updated != null) && !updated.equals(getValue())) {
+                setValue(updated);
+                return true;
+            }
+            return false;
+        }
+    }
+
+    static class StringSetting extends MarvelSetting<String> {
+
+        StringSetting(String name, String description, String defaultValue) {
+            super(name, description, defaultValue);
+        }
+
+        @Override
+        boolean onInit(Settings settings) {
+            setValue(settings.get(getName(), getDefaultValue()));
+            return true;
+        }
+
+        @Override
+        boolean onRefresh(Settings settings) {
+            String updated = settings.get(getName(), null);
+            if ((updated != null) && !updated.equals(getValue())) {
+                setValue(updated);
+                return true;
+            }
+            return false;
+        }
+    }
+
+    static class StringArraySetting extends MarvelSetting<String[]> {
+
+        StringArraySetting(String name, String description, String[] defaultValue) {
+            super(name, description, defaultValue);
+        }
+
+        @Override
+        boolean onInit(Settings settings) {
+            String[] a;
+            if (getDefaultValue() != null) {
+                a = settings.getAsArray(getName(), getDefaultValue(), true);
+            } else {
+                a = settings.getAsArray(getName());
+            }
+            if (a != null) {
+                setValue(a);
+                return true;
+            }
+            return false;
+        }
+
+        @Override
+        boolean onRefresh(Settings settings) {
+            String[] updated = settings.getAsArray(getName(), null);
+            if (updated != null) {
+                setValue(updated);
+                return true;
+            }
+            return false;
+        }
+
+        @Override
+        public String dynamicSettingName() {
+            // array settings
+            return super.dynamicSettingName() + ".*";
+        }
+
+        @Override
+        public String getValueAsString() {
+            return Strings.arrayToCommaDelimitedString(getValue());
+        }
+    }
+
+    static class TimeValueSetting extends MarvelSetting<TimeValue> {
+
+        TimeValueSetting(String name, String description, TimeValue defaultValue) {
+            super(name, description, defaultValue);
+        }
+
+        @Override
+        boolean onInit(Settings settings) {
+            TimeValue t = get(settings, getDefaultValue());
+            if (t != null) {
+                setValue(t);
+                return true;
+            }
+            return false;
+        }
+
+        @Override
+        boolean onRefresh(Settings settings) {
+            TimeValue updated = get(settings, null);
+            if ((updated != null) && ((getValue() == null) || (updated.millis() != getValue().millis()))) {
+                setValue(updated);
+                return true;
+            }
+            return false;
+        }
+
+        private TimeValue get(Settings settings, TimeValue defaultValue) {
+            try {
+                TimeValue t = settings.getAsTime(getName(), defaultValue);
+                if (t != null) {
+                    return t;
+                }
+            } catch (ElasticsearchParseException e) {
+                Long l = settings.getAsLong(getName(), defaultValue != null ? defaultValue.millis() : null);
+                if (l != null) {
+                    return TimeValue.timeValueMillis(l);
+                }
+            }
+            return null;
+        }
+    }
+}

marvel/src/main/java/org/elasticsearch/marvel/agent/settings/MarvelSettingsModule.java

@@ -0,0 +1,16 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.marvel.agent.settings;
+
+import org.elasticsearch.common.inject.AbstractModule;
+
+public class MarvelSettingsModule extends AbstractModule {
+
+    @Override
+    protected void configure() {
+        bind(MarvelSettingsService.class).asEagerSingleton();
+    }
+}

marvel/src/main/java/org/elasticsearch/marvel/agent/settings/MarvelSettingsService.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.marvel.agent.settings;
+
+import com.google.common.collect.ImmutableList;
+import org.elasticsearch.cluster.settings.ClusterDynamicSettings;
+import org.elasticsearch.cluster.settings.DynamicSettings;
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.component.AbstractComponent;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.marvel.MarvelPlugin;
+import org.elasticsearch.marvel.agent.settings.MarvelSetting.StringArraySetting;
+import org.elasticsearch.marvel.agent.settings.MarvelSetting.TimeValueSetting;
+import org.elasticsearch.node.settings.NodeSettingsService;
+
+import java.util.List;
+
+public class MarvelSettingsService extends AbstractComponent implements NodeSettingsService.Listener {
+
+    private static final String PREFIX = MarvelPlugin.NAME + ".agent.";
+
+    private final List<MarvelSetting> settings;
+
+    final TimeValueSetting indexStatsTimeout = MarvelSetting.timeSetting(PREFIX + "index.stats.timeout", TimeValue.timeValueMinutes(10),
+            "Timeout value when collecting Index Stats (default to 10m)");
+
+    final StringArraySetting indices = MarvelSetting.arraySetting(PREFIX + "indices", Strings.EMPTY_ARRAY,
+            "List of indices names whose stats will be exported (default to all indices)");
+
+
+    MarvelSettingsService(Settings clusterSettings) {
+        super(clusterSettings);
+
+        // List of marvel settings
+        ImmutableList.Builder<MarvelSetting> builder = ImmutableList.builder();
+        builder.add(indexStatsTimeout);
+        builder.add(indices);
+        this.settings = builder.build();
+
+        logger.trace("initializing marvel settings:");
+        for (MarvelSetting setting : settings) {
+            // Initialize all settings and register them as a dynamic settings
+            if (setting.onInit(clusterSettings)) {
+                logger.trace("\t{} ({}) initialized to [{}]", setting.getName(), setting.getDescription(), setting.getValueAsString());
+            } else {
+                logger.trace("\t{} ({}) initialized", setting.getName(), setting.getDescription());
+            }
+        }
+    }
+
+    @Inject
+    public MarvelSettingsService(Settings clusterSettings, NodeSettingsService nodeSettingsService, @ClusterDynamicSettings DynamicSettings dynamicSettings) {
+        this(clusterSettings);
+
+        logger.trace("registering dynamic marvel settings:");
+        for (MarvelSetting setting : settings) {
+            if (setting.isDynamic()) {
+                logger.trace("dynamic setting [{}] registered", setting.getName());
+                dynamicSettings.addDynamicSetting(setting.dynamicSettingName());
+            }
+        }
+
+        logger.trace("registering the service as a node settings listener");
+        nodeSettingsService.addListener(this);
+    }
+
+    @Override
+    public void onRefreshSettings(Settings clusterSettings) {
+        for (MarvelSetting setting : settings) {
+            if (setting.onRefresh(clusterSettings)) {
+                logger.trace("setting [{}] updated to [{}]", setting.getName(), setting.getValueAsString());
+            }
+        }
+    }
+
+    public TimeValue indexStatsTimeout() {
+        return indexStatsTimeout.getValue();
+    }
+
+    public String[] indices() {
+        return indices.getValue();
+    }
+}

marvel/src/test/java/org/elasticsearch/marvel/agent/collector/indices/IndexStatsCollectorTests.java

@@ -9,6 +9,7 @@ import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.cluster.ClusterService;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.marvel.agent.exporter.MarvelDoc;
+import org.elasticsearch.marvel.agent.settings.MarvelSettingsService;
 import org.elasticsearch.test.ElasticsearchSingleNodeTest;
 import org.junit.Test;
 
@@ -107,6 +108,10 @@ public class IndexStatsCollectorTests extends ElasticsearchSingleNodeTest {
     }
 
     private IndexStatsCollector newIndexStatsCollector() {
-        return new IndexStatsCollector(getInstanceFromNode(Settings.class), getInstanceFromNode(ClusterService.class), getInstanceFromNode(ClusterName.class), client());
+        return new IndexStatsCollector(getInstanceFromNode(Settings.class),
+                getInstanceFromNode(ClusterService.class),
+                getInstanceFromNode(ClusterName.class),
+                client(),
+                getInstanceFromNode(MarvelSettingsService.class));
     }
 }

marvel/src/test/java/org/elasticsearch/marvel/agent/settings/MarvelSettingTests.java

@@ -0,0 +1,151 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.marvel.agent.settings;
+
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.test.ElasticsearchTestCase;
+import org.junit.Test;
+
+import static org.elasticsearch.common.settings.Settings.settingsBuilder;
+import static org.hamcrest.Matchers.equalTo;
+
+public class MarvelSettingTests extends ElasticsearchTestCase {
+
+    @Test
+    public void testBooleanMarvelSetting() {
+        String name = randomAsciiOfLength(10);
+        String description = randomAsciiOfLength(20);
+        Boolean defaultValue = null;
+        if (randomBoolean()) {
+            defaultValue = randomBoolean();
+        }
+
+        MarvelSetting.BooleanSetting setting = MarvelSetting.booleanSetting(name, defaultValue, description);
+        assertThat(setting.getName(), equalTo(name));
+        assertThat(setting.getDescription(), equalTo(description));
+        assertThat(setting.getDefaultValue(), equalTo(defaultValue));
+
+        setting.onInit(settingsBuilder().build());
+        assertThat(setting.getValue(), equalTo(defaultValue));
+
+        setting.onInit(settingsBuilder().put(name, Boolean.FALSE).build());
+        assertFalse(setting.getValue());
+
+        setting.onRefresh(settingsBuilder().put(name, Boolean.TRUE).build());
+        assertTrue(setting.getValue());
+    }
+
+    @Test
+    public void testTimeValueMarvelSetting() {
+        String name = randomAsciiOfLength(10);
+        String description = randomAsciiOfLength(20);
+        TimeValue defaultValue = null;
+        if (randomBoolean()) {
+            defaultValue = randomTimeValue();
+        }
+
+        MarvelSetting.TimeValueSetting setting = MarvelSetting.timeSetting(name, defaultValue, description);
+        assertThat(setting.getName(), equalTo(name));
+        assertThat(setting.getDescription(), equalTo(description));
+        if (defaultValue == null) {
+            assertNull(setting.getDefaultValue());
+        } else {
+            assertThat(setting.getDefaultValue().millis(), equalTo(defaultValue.millis()));
+        }
+
+        setting.onInit(settingsBuilder().build());
+        if (defaultValue == null) {
+            assertNull(setting.getValue());
+        } else {
+            assertThat(setting.getValue().millis(), equalTo(defaultValue.millis()));
+        }
+
+        setting.onInit(settingsBuilder().put(name, 15000L).build());
+        assertThat(setting.getValue().millis(), equalTo(15000L));
+
+        TimeValue updated = randomTimeValue();
+        setting.onInit(settingsBuilder().put(name, updated.toString()).build());
+        assertThat(setting.getValue().millis(), equalTo(updated.millis()));
+
+        updated = randomTimeValue();
+        setting.onRefresh(settingsBuilder().put(name, updated.toString()).build());
+        assertThat(setting.getValue().millis(), equalTo(updated.millis()));
+    }
+
+    @Test
+    public void testStringMarvelSetting() {
+        String name = randomAsciiOfLength(10);
+        String description = randomAsciiOfLength(20);
+        String defaultValue = null;
+        if (randomBoolean()) {
+            defaultValue = randomAsciiOfLength(15);
+        }
+
+        MarvelSetting.StringSetting setting = MarvelSetting.stringSetting(name, defaultValue, description);
+        assertThat(setting.getName(), equalTo(name));
+        assertThat(setting.getDescription(), equalTo(description));
+        assertThat(setting.getDefaultValue(), equalTo(defaultValue));
+
+        setting.onInit(settingsBuilder().build());
+        assertThat(setting.getValue(), equalTo(defaultValue));
+
+        String updated = randomAsciiOfLength(15);
+        setting.onInit(settingsBuilder().put(name, updated).build());
+        assertThat(setting.getValue(), equalTo(updated));
+
+        updated = randomAsciiOfLength(15);
+        setting.onRefresh(settingsBuilder().put(name, updated).build());
+        assertThat(setting.getValue(), equalTo(updated));
+    }
+
+    @Test
+    public void testStringArrayMarvelSetting() {
+        String name = randomAsciiOfLength(10);
+        String description = randomAsciiOfLength(20);
+        String[] defaultValue = null;
+        if (randomBoolean()) {
+            defaultValue = randomStringArray();
+        }
+
+        MarvelSetting.StringArraySetting setting = MarvelSetting.arraySetting(name, defaultValue, description);
+        assertThat(setting.getName(), equalTo(name));
+        assertThat(setting.getDescription(), equalTo(description));
+        if (defaultValue == null) {
+            assertNull(setting.getDefaultValue());
+        } else {
+            assertArrayEquals(setting.getDefaultValue(), defaultValue);
+        }
+
+        setting.onInit(settingsBuilder().build());
+        if (defaultValue == null) {
+            assertArrayEquals(setting.getValue(), Strings.EMPTY_ARRAY);
+        } else {
+            assertArrayEquals(setting.getValue(), defaultValue);
+        }
+
+        String[] updated = randomStringArray();
+        setting.onInit(settingsBuilder().put(name, Strings.arrayToCommaDelimitedString(updated)).build());
+        assertArrayEquals(setting.getValue(), updated);
+
+        updated = randomStringArray();
+        setting.onRefresh(settingsBuilder().put(name, Strings.arrayToCommaDelimitedString(updated)).build());
+        assertArrayEquals(setting.getValue(), updated);
+    }
+
+    private TimeValue randomTimeValue() {
+        return TimeValue.parseTimeValue(randomFrom("10ms", "1.5s", "1.5m", "1.5h", "1.5d", "1000d"), null, getClass().getSimpleName() + ".unit");
+    }
+
+    private String[] randomStringArray() {
+        int n = randomIntBetween(1, 5);
+        String[] values = new String[n];
+        for (int i = 0; i < n; i++) {
+            values[i] = randomAsciiOfLength(5);
+        }
+        return values;
+    }
+}

marvel/src/test/java/org/elasticsearch/marvel/agent/settings/MarvelSettingsServiceTests.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.marvel.agent.settings;
+
+import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.unit.TimeValue;
+import org.elasticsearch.test.ElasticsearchTestCase;
+import org.junit.Test;
+
+import static org.elasticsearch.common.settings.Settings.settingsBuilder;
+import static org.hamcrest.Matchers.equalTo;
+
+public class MarvelSettingsServiceTests extends ElasticsearchTestCase {
+
+    @Test
+    public void testMarvelSettingService() {
+        MarvelSettingsService service = new MarvelSettingsService(Settings.EMPTY);
+
+        TimeValue indexStatsTimeout = service.indexStatsTimeout();
+        assertNotNull(indexStatsTimeout);
+
+        String[] indices = service.indices();
+        assertNotNull(indices);
+
+        TimeValue updatedIndexStatsTimeout = TimeValue.timeValueSeconds(60L);
+        String[] updatedIndices = new String[]{"index-0", "index-1"};
+
+        Settings settings = settingsBuilder()
+                .put(service.indexStatsTimeout.getName(), updatedIndexStatsTimeout)
+                .put(service.indices.getName(), Strings.arrayToCommaDelimitedString(updatedIndices))
+                .build();
+
+        service.onRefreshSettings(settings);
+
+        assertThat(service.indexStatsTimeout(), equalTo(updatedIndexStatsTimeout));
+        assertArrayEquals(service.indices(), updatedIndices);
+    }
+}