Deprecate the logstash enabled setting (#53487)

The setting, `xpack.logstash.enabled`, exists to enable or disable the
logstash extensions found within x-pack. In practice, this setting had
no effect on the functionality of the extension. Given this, the
setting is now deprecated in preparation for removal.

Backport of #53367

Author: jaymode

x-pack/plugin/ccr/src/test/java/org/elasticsearch/xpack/CcrIntegTestCase.java

@@ -225,7 +225,6 @@ private NodeConfigurationSource createNodeConfigurationSource(final String leade
         builder.put(XPackSettings.MONITORING_ENABLED.getKey(), false);
         builder.put(XPackSettings.WATCHER_ENABLED.getKey(), false);
         builder.put(XPackSettings.MACHINE_LEARNING_ENABLED.getKey(), false);
-        builder.put(XPackSettings.LOGSTASH_ENABLED.getKey(), false);
         builder.put(LicenseService.SELF_GENERATED_LICENSE_TYPE.getKey(), "trial");
         // Let cluster state api return quickly in order to speed up auto follow tests:
         builder.put(CcrSettings.CCR_WAIT_FOR_METADATA_TIMEOUT.getKey(), TimeValue.timeValueMillis(100));

x-pack/plugin/ccr/src/test/java/org/elasticsearch/xpack/CcrSingleNodeTestCase.java

@@ -48,7 +48,6 @@ protected Settings nodeSettings() {
         builder.put(XPackSettings.MONITORING_ENABLED.getKey(), false);
         builder.put(XPackSettings.WATCHER_ENABLED.getKey(), false);
         builder.put(XPackSettings.MACHINE_LEARNING_ENABLED.getKey(), false);
-        builder.put(XPackSettings.LOGSTASH_ENABLED.getKey(), false);
         builder.put(LicenseService.SELF_GENERATED_LICENSE_TYPE.getKey(), "trial");
         // Let cluster state api return quickly in order to speed up auto follow tests:
         builder.put(CcrSettings.CCR_WAIT_FOR_METADATA_TIMEOUT.getKey(), TimeValue.timeValueMillis(100));

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/XPackSettings.java

@@ -88,7 +88,7 @@ private XPackSettings() {
 
     /** Setting for enabling or disabling Logstash extensions. Defaults to true. */
     public static final Setting<Boolean> LOGSTASH_ENABLED = Setting.boolSetting("xpack.logstash.enabled", true,
-            Setting.Property.NodeScope);
+            Setting.Property.NodeScope, Property.Deprecated);
 
     /**
      * Setting for enabling or disabling the index lifecycle extension. Defaults to true.

x-pack/plugin/ilm/src/test/java/org/elasticsearch/xpack/ilm/IndexLifecycleInitialisationTests.java

@@ -101,7 +101,6 @@ protected Settings nodeSettings(int nodeOrdinal) {
         settings.put(XPackSettings.WATCHER_ENABLED.getKey(), false);
         settings.put(XPackSettings.MONITORING_ENABLED.getKey(), false);
         settings.put(XPackSettings.GRAPH_ENABLED.getKey(), false);
-        settings.put(XPackSettings.LOGSTASH_ENABLED.getKey(), false);
         settings.put(LifecycleSettings.LIFECYCLE_POLL_INTERVAL, "1s");
 
         // This is necessary to prevent ILM and SLM installing a lifecycle policy, these tests assume a blank slate

x-pack/plugin/ilm/src/test/java/org/elasticsearch/xpack/slm/SnapshotLifecycleInitialisationTests.java

@@ -50,7 +50,6 @@ protected Settings nodeSettings() {
         settings.put(XPackSettings.WATCHER_ENABLED.getKey(), false);
         settings.put(XPackSettings.MONITORING_ENABLED.getKey(), false);
         settings.put(XPackSettings.GRAPH_ENABLED.getKey(), false);
-        settings.put(XPackSettings.LOGSTASH_ENABLED.getKey(), false);
         settings.put(Environment.PATH_REPO_SETTING.getKey(), repositoryLocation);
 
         settings.put(XPackSettings.SNAPSHOT_LIFECYCLE_ENABLED.getKey(), true);

x-pack/plugin/logstash/src/main/java/org/elasticsearch/xpack/logstash/Logstash.java

@@ -15,7 +15,6 @@
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.plugins.SystemIndexPlugin;
 import org.elasticsearch.xpack.core.XPackPlugin;
-import org.elasticsearch.xpack.core.XPackSettings;
 import org.elasticsearch.xpack.core.template.TemplateUtils;
 
 import java.util.ArrayList;
@@ -36,21 +35,7 @@ public class Logstash extends Plugin implements SystemIndexPlugin {
     private static final String OLD_LOGSTASH_INDEX_NAME = "logstash-index-template";
     private static final String TEMPLATE_VERSION_VARIABLE = "logstash.template.version";
 
-    private final boolean enabled;
-    private final boolean transportClientMode;
-
-    public Logstash(Settings settings) {
-        this.enabled = XPackSettings.LOGSTASH_ENABLED.get(settings);
-        this.transportClientMode = XPackPlugin.transportClientMode(settings);
-    }
-
-    boolean isEnabled() {
-        return enabled;
-    }
-
-    boolean isTransportClient() {
-        return transportClientMode;
-    }
+    public Logstash() {}
 
     public Collection<Module> createGuiceModules() {
         List<Module> modules = new ArrayList<>();

x-pack/plugin/logstash/src/test/java/org/elasticsearch/xpack/logstash/LogstashFeatureSetTests.java

@@ -7,10 +7,12 @@
 
 import org.elasticsearch.action.support.PlainActionFuture;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.license.XPackLicenseState;
 import org.elasticsearch.test.ESTestCase;
 import org.elasticsearch.xpack.core.XPackFeatureSet;
+import org.elasticsearch.xpack.core.XPackSettings;
 import org.elasticsearch.xpack.core.logstash.LogstashFeatureSetUsage;
 
 import static org.mockito.Mockito.mock;
@@ -33,6 +35,8 @@ public void testEnabledSetting() throws Exception {
         usage.writeTo(out);
         XPackFeatureSet.Usage serializedUsage = new LogstashFeatureSetUsage(out.bytes().streamInput());
         assertThat(serializedUsage.enabled(), is(enabled));
+
+        assertSettingDeprecationsAndWarnings(new Setting<?>[] { XPackSettings.LOGSTASH_ENABLED });
     }
 
     public void testEnabledDefault() throws Exception {