Allow copying source settings on resize operation

docs/reference/indices/shrink-index.asciidoc

@@ -121,8 +121,13 @@ POST my_source_index/_shrink/my_target_index
 
 NOTE: Mappings may not be specified in the `_shrink` request.
 
-NOTE: By default, with the exception of `index.analysis`, `index.similarity`, and `index.sort` settings, index settings on the source
-index are not copied during a shrink operation.
+NOTE: By default, with the exception of `index.analysis`, `index.similarity`,
+and `index.sort` settings, index settings on the source index are not copied
+during a shrink operation. With the exception of non-copyable settings, settings
+from the source index can be copied to the target index by adding the URL
+parameter `copy_settings=true` to the request.
+
+deprecated[7.0.0, `copy_settings` will default to `true` in 8.x and will be removed in 9.0.0]
 
 [float]
 === Monitoring the shrink process

docs/reference/indices/split-index.asciidoc

@@ -177,8 +177,13 @@ POST my_source_index/_split/my_target_index
 
 NOTE: Mappings may not be specified in the `_split` request.
 
-NOTE: By default, with the exception of `index.analysis`, `index.similarity`, and `index.sort` settings, index settings on the source
-index are not copied during a shrink operation.
+NOTE: By default, with the exception of `index.analysis`, `index.similarity`,
+and `index.sort` settings, index settings on the source index are not copied
+during a split operation. With the exception of non-copyable settings, settings
+from the source index can be copied to the target index by adding the URL
+parameter `copy_settings=true` to the request.
+
+deprecated[7.0.0, `copy_settings` will default to `true` in 8.x and will be removed in 9.0.0]
 
 [float]
 === Monitoring the split process

docs/reference/migration/migrate_7_0/api.asciidoc

@@ -61,8 +61,23 @@ backwards compatibility. Backwards support for the `suggest` metric was
 deprecated in 6.3.0 and now removed in 7.0.0.
 
 [[remove-field-caps-body]]
-==== In the fields capabilities API, `fields` can no longer be provided in the request body.
 
 In the past, `fields` could be provided either as a parameter, or as part of the request
 body. Specifying `fields` in the request body as opposed to a parameter was deprecated
 in 6.4.0, and is now unsupported in 7.0.0.
+
+==== Copying source settings during shrink/split operations
+
+In prior versions of Elasticsearch, resize operations (shrink/split) would only
+copy `index.analysis`, `index.similarity`, and `index.sort` settings from the
+source index. Elasticsearch 7.0.0 introduces a request parameter `copy_settings`
+which will copy all index settings from the source except for non-copyable index
+settings. This parameter defaults to `false` in 7.x, is immediately deprecated
+in 7.0.0, will only be able to be set to `true` in 8.x, and will be removed in
+9.0.0. Note than when this parameter is used it means that all copyable settings
+will be copied; this includes the index blocks that must be put in place for a
+resize operation, and any allocation settings put in place in preparation for
+executing the resize operation. If you use this parameter, you will either have
+to follow up the operation with a request to adjust to the desired settings on
+the target index, or send the desired value of these settings with the resize
+operation.

rest-api-spec/src/main/resources/rest-api-spec/api/indices.shrink.json

@@ -18,6 +18,10 @@
         }
       },
       "params": {
+        "copy_settings": {
+          "type" : "boolean",
+          "description" : "whether or not to copy settings from the source index (defaults to false)"
+        },
         "timeout": {
           "type" : "time",
           "description" : "Explicit operation timeout"

rest-api-spec/src/main/resources/rest-api-spec/api/indices.split.json

@@ -18,6 +18,10 @@
         }
       },
       "params": {
+        "copy_settings": {
+          "type" : "boolean",
+          "description" : "whether or not to copy settings from the source index (defaults to false)"
+        },
         "timeout": {
           "type" : "time",
           "description" : "Explicit operation timeout"

rest-api-spec/src/main/resources/rest-api-spec/test/indices.shrink/30_copy_settings.yml

@@ -0,0 +1,92 @@
+---
+"Copy settings during shrink index":
+  - skip:
+      version: " - 6.99.99"
+      reason:  copy_settings did not exist prior to 7.0.0
+      features: "warnings"
+
+  - do:
+      cluster.state: {}
+
+  # get master node id
+  - set: { master_node: master }
+
+  - do:
+      indices.create:
+        index: source
+        wait_for_active_shards: 1
+        body:
+          settings:
+            # ensure everything is allocated on the master node
+            index.routing.allocation.include._id: $master
+            index.number_of_replicas: 0
+            index.merge.scheduler.max_merge_count: 4
+
+  # make it read-only
+  - do:
+      indices.put_settings:
+        index: source
+        body:
+          index.blocks.write: true
+          index.number_of_replicas: 0
+
+  - do:
+      cluster.health:
+        wait_for_status: green
+        index: source
+
+  # now we do a actual shrink and copy settings
+  - do:
+      indices.shrink:
+        index: "source"
+        target: "copy-settings-target"
+        wait_for_active_shards: 1
+        master_timeout: 10s
+        copy_settings: true
+        body:
+          settings:
+            index.number_of_replicas: 0
+            index.merge.scheduler.max_thread_count: 2
+      warnings:
+        - "parameter [copy_settings] is deprecated but was [true]"
+
+  - do:
+      cluster.health:
+        wait_for_status: green
+
+  - do:
+      indices.get_settings:
+        index: "copy-settings-target"
+
+  - match: { copy-settings-target.settings.index.merge.scheduler.max_merge_count: "4" }
+  - match: { copy-settings-target.settings.index.merge.scheduler.max_thread_count: "2" }
+  - match: { copy-settings-target.settings.index.blocks.write: "true" }
+  - match: { copy-settings-target.settings.index.routing.allocation.include._id: $master }
+
+  # now we do a actual shrink and do not copy settings
+  - do:
+      indices.shrink:
+        index: "source"
+        target: "no-copy-settings-target"
+        wait_for_active_shards: 1
+        master_timeout: 10s
+        copy_settings: false
+        body:
+          settings:
+            index.number_of_replicas: 0
+            index.merge.scheduler.max_thread_count: 2
+      warnings:
+        - "parameter [copy_settings] is deprecated but was [false]"
+
+  - do:
+      cluster.health:
+        wait_for_status: green
+
+  - do:
+      indices.get_settings:
+        index: "no-copy-settings-target"
+
+  - is_false: no-copy-settings-target.settings.index.merge.scheduler.max_merge_count
+  - match: { no-copy-settings-target.settings.index.merge.scheduler.max_thread_count: "2" }
+  - is_false: no-copy-settings-target.settings.index.blocks.write
+  - is_false: no-copy-settings-target.settings.index.routing.allocation.include._id

rest-api-spec/src/main/resources/rest-api-spec/test/indices.split/30_copy_settings.yml

@@ -0,0 +1,96 @@
+---
+"Copy settings during split index":
+  - skip:
+      version: " - 6.99.99"
+      reason:  copy_settings did not exist prior to 7.0.0
+      features: "warnings"
+
+  - do:
+      cluster.state: {}
+
+  # get master node id
+  - set: { master_node: master }
+
+  - do:
+      indices.create:
+        index: source
+        wait_for_active_shards: 1
+        body:
+          settings:
+            # ensure everything is allocated on the master node
+            index.routing.allocation.include._id: $master
+            index.number_of_replicas: 0
+            index.number_of_shards: 1
+            index.number_of_routing_shards: 4
+            index.merge.scheduler.max_merge_count: 4
+
+  # make it read-only
+  - do:
+      indices.put_settings:
+        index: source
+        body:
+          index.blocks.write: true
+          index.number_of_replicas: 0
+
+  - do:
+      cluster.health:
+        wait_for_status: green
+        index: source
+
+  # now we do a actual split and copy settings
+  - do:
+      indices.split:
+        index: "source"
+        target: "copy-settings-target"
+        wait_for_active_shards: 1
+        master_timeout: 10s
+        copy_settings: true
+        body:
+          settings:
+            index.number_of_replicas: 0
+            index.number_of_shards: 2
+            index.merge.scheduler.max_thread_count: 2
+      warnings:
+        - "parameter [copy_settings] is deprecated but was [true]"
+
+  - do:
+      cluster.health:
+        wait_for_status: green
+
+  - do:
+      indices.get_settings:
+        index: "copy-settings-target"
+
+  - match: { copy-settings-target.settings.index.merge.scheduler.max_merge_count: "4" }
+  - match: { copy-settings-target.settings.index.merge.scheduler.max_thread_count: "2" }
+  - match: { copy-settings-target.settings.index.blocks.write: "true" }
+  - match: { copy-settings-target.settings.index.routing.allocation.include._id: $master }
+
+  # now we do a actual shrink and do not copy settings
+  - do:
+      indices.split:
+        index: "source"
+        target: "no-copy-settings-target"
+        wait_for_active_shards: 1
+        master_timeout: 10s
+        copy_settings: false
+        body:
+          settings:
+            index.number_of_replicas: 0
+            index.number_of_shards: 2
+            index.merge.scheduler.max_thread_count: 2
+      warnings:
+        - "parameter [copy_settings] is deprecated but was [false]"
+
+  - do:
+      cluster.health:
+        wait_for_status: green
+
+  - do:
+      indices.get_settings:
+        index: "no-copy-settings-target"
+
+  - is_false: no-copy-settings-target.settings.index.merge.scheduler.max_merge_count
+  - match: { no-copy-settings-target.settings.index.merge.scheduler.max_thread_count: "2" }
+  - is_false: no-copy-settings-target.settings.index.blocks.write
+  - is_false: no-copy-settings-target.settings.index.routing.allocation.include._id

server/src/main/java/org/elasticsearch/action/admin/indices/create/CreateIndexClusterStateUpdateRequest.java

@@ -45,6 +45,7 @@ public class CreateIndexClusterStateUpdateRequest extends ClusterStateUpdateRequ
     private final String providedName;
     private Index recoverFrom;
     private ResizeType resizeType;
+    private boolean copySettings;
 
     private IndexMetaData.State state = IndexMetaData.State.OPEN;
 
@@ -112,6 +113,11 @@ public CreateIndexClusterStateUpdateRequest resizeType(ResizeType resizeType) {
         return this;
     }
 
+    public CreateIndexClusterStateUpdateRequest copySettings(final boolean copySettings) {
+        this.copySettings = copySettings;
+        return this;
+    }
+
     public TransportMessage originalMessage() {
         return originalMessage;
     }
@@ -170,4 +176,9 @@ public ActiveShardCount waitForActiveShards() {
     public ResizeType resizeType() {
         return resizeType;
     }
+
+    public boolean copySettings() {
+        return copySettings;
+    }
+
 }

server/src/main/java/org/elasticsearch/action/admin/indices/shrink/ResizeRequest.java

@@ -18,6 +18,7 @@
  */
 package org.elasticsearch.action.admin.indices.shrink;
 
+import org.elasticsearch.Version;
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.IndicesRequest;
 import org.elasticsearch.action.admin.indices.alias.Alias;
@@ -55,6 +56,7 @@ public class ResizeRequest extends AcknowledgedRequest<ResizeRequest> implements
     private CreateIndexRequest targetIndexRequest;
     private String sourceIndex;
     private ResizeType type = ResizeType.SHRINK;
+    private boolean copySettings = false;
 
     ResizeRequest() {}
 
@@ -96,6 +98,11 @@ public void readFrom(StreamInput in) throws IOException {
         } else {
             type = ResizeType.SHRINK; // BWC this used to be shrink only
         }
+        if (in.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+            copySettings = in.readBoolean();
+        } else {
+            copySettings = false;
+        }
     }
 
     @Override
@@ -106,6 +113,9 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getVersion().onOrAfter(ResizeAction.COMPATIBILITY_VERSION)) {
             out.writeEnum(type);
         }
+        if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+            out.writeBoolean(copySettings);
+        }
     }
 
     @Override
@@ -177,6 +187,14 @@ public ResizeType getResizeType() {
         return type;
     }
 
+    public void setCopySettings(final boolean copySettings) {
+        this.copySettings = copySettings;
+    }
+
+    public boolean getCopySettings() {
+        return copySettings;
+    }
+
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
         builder.startObject();

server/src/main/java/org/elasticsearch/action/admin/indices/shrink/TransportResizeAction.java

@@ -178,19 +178,19 @@ static CreateIndexClusterStateUpdateRequest prepareCreateIndexRequest(final Resi
         settingsBuilder.put("index.number_of_shards", numShards);
         targetIndex.settings(settingsBuilder);
 
-        return new CreateIndexClusterStateUpdateRequest(targetIndex,
-            cause, targetIndex.index(), targetIndexName)
-            // mappings are updated on the node when creating in the shards, this prevents race-conditions since all mapping must be
-            // applied once we took the snapshot and if somebody messes things up and switches the index read/write and adds docs we miss
-            // the mappings for everything is corrupted and hard to debug
-            .ackTimeout(targetIndex.timeout())
-            .masterNodeTimeout(targetIndex.masterNodeTimeout())
-            .settings(targetIndex.settings())
-            .aliases(targetIndex.aliases())
-            .customs(targetIndex.customs())
-            .waitForActiveShards(targetIndex.waitForActiveShards())
-            .recoverFrom(metaData.getIndex())
-            .resizeType(resizeRequest.getResizeType());
+        return new CreateIndexClusterStateUpdateRequest(targetIndex, cause, targetIndex.index(), targetIndexName)
+                // mappings are updated on the node when creating in the shards, this prevents race-conditions since all mapping must be
+                // applied once we took the snapshot and if somebody messes things up and switches the index read/write and adds docs we
+                // miss the mappings for everything is corrupted and hard to debug
+                .ackTimeout(targetIndex.timeout())
+                .masterNodeTimeout(targetIndex.masterNodeTimeout())
+                .settings(targetIndex.settings())
+                .aliases(targetIndex.aliases())
+                .customs(targetIndex.customs())
+                .waitForActiveShards(targetIndex.waitForActiveShards())
+                .recoverFrom(metaData.getIndex())
+                .resizeType(resizeRequest.getResizeType())
+                .copySettings(resizeRequest.getCopySettings());
     }
 
     @Override