Add a deprecation notice to shadow replicas

core/src/main/java/org/elasticsearch/cluster/metadata/IndexMetaData.java

@@ -190,11 +190,11 @@ static Setting<Integer> buildNumberOfShardsSetting() {
         Setting.intSetting(SETTING_NUMBER_OF_REPLICAS, 1, 0, Property.Dynamic, Property.IndexScope);
     public static final String SETTING_SHADOW_REPLICAS = "index.shadow_replicas";
     public static final Setting<Boolean> INDEX_SHADOW_REPLICAS_SETTING =
-        Setting.boolSetting(SETTING_SHADOW_REPLICAS, false, Property.IndexScope);
+        Setting.boolSetting(SETTING_SHADOW_REPLICAS, false, Property.IndexScope, Property.Deprecated);
 
     public static final String SETTING_SHARED_FILESYSTEM = "index.shared_filesystem";
     public static final Setting<Boolean> INDEX_SHARED_FILESYSTEM_SETTING =
-        Setting.boolSetting(SETTING_SHARED_FILESYSTEM, false, Property.IndexScope);
+        Setting.boolSetting(SETTING_SHARED_FILESYSTEM, INDEX_SHADOW_REPLICAS_SETTING, Property.IndexScope, Property.Deprecated);
 
     public static final String SETTING_AUTO_EXPAND_REPLICAS = "index.auto_expand_replicas";
     public static final Setting<AutoExpandReplicas> INDEX_AUTO_EXPAND_REPLICAS_SETTING = AutoExpandReplicas.SETTING;
@@ -232,10 +232,11 @@ static Setting<Integer> buildNumberOfShardsSetting() {
     public static final String SETTING_INDEX_UUID = "index.uuid";
     public static final String SETTING_DATA_PATH = "index.data_path";
     public static final Setting<String> INDEX_DATA_PATH_SETTING =
-        new Setting<>(SETTING_DATA_PATH, "", Function.identity(), Property.IndexScope);
+        new Setting<>(SETTING_DATA_PATH, "", Function.identity(), Property.IndexScope, Property.Deprecated);
     public static final String SETTING_SHARED_FS_ALLOW_RECOVERY_ON_ANY_NODE = "index.shared_filesystem.recover_on_any_node";
     public static final Setting<Boolean> INDEX_SHARED_FS_ALLOW_RECOVERY_ON_ANY_NODE_SETTING =
-        Setting.boolSetting(SETTING_SHARED_FS_ALLOW_RECOVERY_ON_ANY_NODE, false, Property.Dynamic, Property.IndexScope);
+        Setting.boolSetting(SETTING_SHARED_FS_ALLOW_RECOVERY_ON_ANY_NODE, false,
+            Property.Dynamic, Property.IndexScope, Property.Deprecated);
     public static final String INDEX_UUID_NA_VALUE = "_na_";
 
     public static final String INDEX_ROUTING_REQUIRE_GROUP_PREFIX = "index.routing.allocation.require";
@@ -1217,6 +1218,7 @@ public static IndexMetaData fromXContent(XContentParser parser) throws IOExcepti
      * {@link #isIndexUsingShadowReplicas(org.elasticsearch.common.settings.Settings)}.
      */
     public static boolean isOnSharedFilesystem(Settings settings) {
+        // don't use the settings directly, not to trigger manny deprecation
         return settings.getAsBoolean(SETTING_SHARED_FILESYSTEM, isIndexUsingShadowReplicas(settings));
     }
 
@@ -1226,6 +1228,7 @@ public static boolean isOnSharedFilesystem(Settings settings) {
      * setting for this is <code>false</code>.
      */
     public static boolean isIndexUsingShadowReplicas(Settings settings) {
+        // don't use the settings directly, not to trigger manny deprecation
         return settings.getAsBoolean(SETTING_SHADOW_REPLICAS, false);
     }
 

core/src/main/java/org/elasticsearch/env/Environment.java

@@ -56,7 +56,8 @@ public class Environment {
     public static final Setting<String> PATH_LOGS_SETTING = Setting.simpleString("path.logs", Property.NodeScope);
     public static final Setting<List<String>> PATH_REPO_SETTING =
         Setting.listSetting("path.repo", Collections.emptyList(), Function.identity(), Property.NodeScope);
-    public static final Setting<String> PATH_SHARED_DATA_SETTING = Setting.simpleString("path.shared_data", Property.NodeScope);
+    public static final Setting<String> PATH_SHARED_DATA_SETTING = Setting.simpleString("path.shared_data",
+        Property.NodeScope, Property.Deprecated);
     public static final Setting<String> PIDFILE_SETTING = Setting.simpleString("pidfile", Property.NodeScope);
 
     private final Settings settings;

core/src/main/java/org/elasticsearch/env/NodeEnvironment.java

@@ -38,7 +38,6 @@
 import org.elasticsearch.common.SuppressForbidden;
 import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.io.FileSystemUtils;
-import org.elasticsearch.common.logging.DeprecationLogger;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Setting.Property;
@@ -162,7 +161,7 @@ public String toString() {
      * If true automatically append node lock id to custom data paths.
      */
     public static final Setting<Boolean> ADD_NODE_LOCK_ID_TO_CUSTOM_PATH =
-        Setting.boolSetting("node.add_lock_id_to_custom_path", true, Property.NodeScope);
+        Setting.boolSetting("node.add_lock_id_to_custom_path", true, Property.NodeScope, Property.Deprecated);
 
 
     /**

docs/reference/indices/shadow-replicas.asciidoc

@@ -1,7 +1,7 @@
 [[indices-shadow-replicas]]
 == Shadow replica indices
 
-experimental[]
+deprecated[5.2.0, Shadow replicas don't see much usage and we are planning to remove them]
 
 If you would like to use a shared filesystem, you can use the shadow replicas
 settings to choose where on disk the data for an index should be kept, as well

docs/reference/migration/migrate_6_0/indices.asciidoc

@@ -27,3 +27,8 @@ PUT _template/template_2
 }
 --------------------------------------------------
 // CONSOLE
+
+
+=== Shadow Replicas are deprecated
+
+<<indices-shadow-replicas,Shadow Replicas>> don't see much usage and we are planning to remove them.