[DOCS] Add rollup V2 API docs (#65398)

Changes:

* Documents new `<index>/_rollup` API
* Updates rollup APIs overview page
* Enables rollups V2 in docs integ tests

docs/build.gradle

@@ -52,6 +52,9 @@ testClusters.integTest {
   if (singleNode().testDistribution == DEFAULT) {
     setting 'xpack.license.self_generated.type', 'trial'
     setting 'indices.lifecycle.history_index_enabled', 'false'
+    if (BuildParams.isSnapshotBuild() == true) {
+      systemProperty 'es.rollup_v2_feature_flag_enabled', 'true'
+    }
     if (BuildParams.isSnapshotBuild() == false) {
       systemProperty 'es.autoscaling_feature_flag_registered', 'true'
     }

docs/reference/rest-api/index.asciidoc

@@ -63,7 +63,7 @@ include::{es-repo-dir}/ml/df-analytics/apis/index.asciidoc[]
 include::{es-repo-dir}/migration/migration.asciidoc[]
 include::{es-repo-dir}/indices/apis/reload-analyzers.asciidoc[]
 include::{es-repo-dir}/repositories-metering-api/repositories-metering-apis.asciidoc[]
-include::{es-repo-dir}/rollup/rollup-api.asciidoc[]
+include::{es-repo-dir}/rollup/rollup-apis.asciidoc[]
 include::{es-repo-dir}/search.asciidoc[]
 include::{es-repo-dir}/searchable-snapshots/apis/searchable-snapshots-apis.asciidoc[]
 include::{xes-repo-dir}/rest-api/security.asciidoc[]

docs/reference/rollup/apis/rollup-api.asciidoc

@@ -0,0 +1,187 @@
+[role="xpack"]
+[testenv="basic"]
+[[rollup-api]]
+=== Rollup API
+++++
+<titleabbrev>Rollup</titleabbrev>
+++++
+
+Aggregates an index's time-series data and stores the results in another index.
+For example, you can roll up hourly data into daily or weekly summaries.
+
+[source,console]
+----
+POST /my-index-000001/_rollup
+{
+  "rollup_index": "my-rollup-index",
+  "groups": {
+    "date_histogram": {
+      "field": "@timestamp",
+      "calendar_interval": "1d"
+    },
+    "terms": {
+      "fields": [
+        "my-keyword-field",
+        "my-other-keyword-field"
+      ]
+    }
+  },
+  "metrics": [
+    {
+      "field": "my-numeric-field",
+      "metrics": [
+        "min",
+        "max",
+        "avg"
+      ]
+    }
+  ]
+}
+----
+// TEST[setup:my_index]
+
+[[rollup-api-request]]
+==== {api-request-title}
+
+`PUT /<index>/_rollup`
+
+[[rollup-api-prereqs]]
+==== {api-prereq-title}
+
+If the {es} {security-features} are enabled, you must have the `manage` cluster
+privilege to use this API. See <<security-privileges>>.
+
+[[rollup-api-path-params]]
+==== {api-path-parms-title}
+
+`<index>`::
+(Required, string)
+Index to roll up. Cannot be a <<data-streams,data stream>> or
+<<indices-aliases,index alias>>. Does not support <<multi-index,multi-target
+syntax>> or wildcards (`*`).
+
+[role="child_attributes"]
+[[rollup-api-request-body]]
+==== {api-request-body-title}
+
+`rollup_index`::
+(Required, string)
+Index that stores the rollup results. Cannot be a <<data-streams,data stream>>
+or <<indices-aliases,index alias>>.
++
+If this index does not exist, the request creates it. If the `<index>` is a
+backing index for a data stream, this new index is a backing index for the same
+stream.
+
+`groups`::
+(Required, object)
+Aggregates and stores fields in the rollup.
++
+.Properties of `groups`
+[%collapsible%open]
+====
+`date_histogram`::
+(Required,
+<<search-aggregations-bucket-datehistogram-aggregation,`date_histogram`
+aggregation>> object)
+Groups documents based on a provided time interval.
++
+.Properties of `date_histogram`
+[%collapsible%open]
+=====
+`field`::
+(Required, string)
+<<date,`date`>> or <<date_nanos,`date_nanos`>> field containing a timestamp. If
+you're rolling up a backing index or using the {ecs-ref}[Elastic Common Schema
+(ECS)], we recommend using `@timestamp`.
+
+`calendar_interval` or `fixed_interval`::
+(Required, <<time-units,time units>>)
+Time interval used to group documents. For differences between
+`calendar_interval` and `fixed_interval`, see <<calendar_and_fixed_intervals>>.
++
+TIP: Choose this value carefully. You won't be able to use a smaller interval
+later. For example, you can't aggregate daily rollups into hourly
+summaries. However, smaller time intervals can greatly increase the size of your
+`rollup_index`.
+
+`time_zone`::
+(Optional, string)
+Time zone for the `field`. Valid values are ISO 8601 UTC offsets, such as
+`+01:00` or `-08:00`, and IANA time zone IDs, such as `America/Los_Angeles`.
+Defaults to `+00:00` (UTC).
+=====
+
+`histogram`::
+(Optional, <<search-aggregations-bucket-histogram-aggregation,`histogram`
+aggregation>> object)
+Groups and stores <<number,numeric>> field values based on a provided interval.
++
+.Properties of `histogram`
+[%collapsible%open]
+=====
+`fields`::
+(Required*, array of strings)
+Array of <<number,numeric>> fields to group. If you specify a `histogram`
+object, this property is required.
+
+`interval`::
+(Required*, integer)
+Numeric interval used to group the `fields`. If you specify a `histogram`
+object, this property is required.
+=====
+
+`terms`::
+(Optional, <<search-aggregations-bucket-terms-aggregation,`terms`
+aggregation>> object)
+Stores values for <<keyword,keyword family>> and <<number,numeric>> fields.
++
+.Properties of `terms`
+[%collapsible%open]
+=====
+`fields`::
+(Required*, array of strings)
+Array of <<keyword,keyword family>> and <<number,numeric>> fields to store. If
+you specify a `terms` object, this property is required.
++
+TIP: Avoid storing high-cardinality fields. High-cardinality fields can greatly
+increase the size of your `rollup_index`.
+=====
+====
+
+`metrics`::
+(Optional, array of objects)
+Collects and stores metrics for <<number,numeric>> fields.
++
+.Properties of `metrics` objects
+[%collapsible%open]
+====
+`field`::
+(Required*, string)
+<<number,Numeric>> field to collect metrics for. If you specify a `metrics`
+object, this property is required.
+
+`metrics`::
+(Required*, array)
+Array of metrics to collect. Each value corresponds to a
+<<search-aggregations-metrics,metric aggregation>>. Valid values are
+<<search-aggregations-metrics-min-aggregation,`min`>>,
+<<search-aggregations-metrics-max-aggregation,`max`>>,
+<<search-aggregations-metrics-sum-aggregation,`sum`>>,
+<<search-aggregations-metrics-avg-aggregation,`avg`>>, and
+<<search-aggregations-metrics-valuecount-aggregation,`value_count`>>. You must
+specify at least one value. If you specify a `metrics` object, this property is
+required.
++
+NOTE: The `avg` metric stores both the `sum` and `value_count` values. This lets
+you accurately average rollups over larger time intervals. For example, you can
+accurately roll up hourly averages into daily averages.
+====
+
+`page_size`::
+(Optional, integer)
+Maximum number of rollup results to process at once. Defaults to `1000`. Larger
+values run faster but require more memory.
++
+NOTE: This argument only affects the speed and memory usage of the rollup
+operation. It does not affect the rollup results.

docs/reference/rollup/rollup-api.asciidoc

@@ -1,35 +0,0 @@
-[role="xpack"]
-[testenv="basic"]
-[[rollup-apis]]
-== Rollup APIs
-
-[discrete]
-[[rollup-jobs-endpoint]]
-=== Jobs
-
-* <<rollup-put-job,Create>> or <<rollup-delete-job,delete {rollup-jobs}>>
-* <<rollup-start-job,Start>> or <<rollup-stop-job,stop {rollup-jobs}>>
-* <<rollup-get-job,Get {rollup-jobs}>>
-
-[discrete]
-[[rollup-data-endpoint]]
-=== Data
-
-* <<rollup-get-rollup-caps,Get Rollup Capabilities>>
-* <<rollup-get-rollup-index-caps,Get Rollup Index Capabilities>>
-
-[discrete]
-[[rollup-search-endpoint]]
-=== Search
-
-* <<rollup-search,Rollup Search>>
-
-
-include::apis/put-job.asciidoc[]
-include::apis/delete-job.asciidoc[]
-include::apis/get-job.asciidoc[]
-include::apis/rollup-caps.asciidoc[]
-include::apis/rollup-index-caps.asciidoc[]
-include::apis/rollup-search.asciidoc[]
-include::apis/start-job.asciidoc[]
-include::apis/stop-job.asciidoc[]

docs/reference/rollup/rollup-apis.asciidoc

@@ -0,0 +1,88 @@
+[role="xpack"]
+[testenv="basic"]
+[[rollup-apis]]
+== Rollup APIs
+
+ifdef::permanently-unreleased-branch[]
+
+A rollup aggregates an index's time-series data and stores the results in
+another index, called a rollup index. For example, you can roll up hourly data
+into daily or weekly summaries.
+
+* <<rollup-api,Rollup API>>
+
+[discrete]
+[[legacy-rollup-apis]]
+=== Legacy rollup APIs
+
+Prior to {es} 7.x, you could only create rollups using periodic cron jobs.
+Special APIs were required to manage the jobs and search the resulting rollup
+indices. These rollup APIs are now deprecated and will be removed in a future
+release.
+
+[discrete]
+[[rollup-jobs-endpoint]]
+==== Jobs
+
+* <<rollup-put-job,Create>> or <<rollup-delete-job,delete {rollup-jobs}>>
+* <<rollup-start-job,Start>> or <<rollup-stop-job,stop {rollup-jobs}>>
+* <<rollup-get-job,Get {rollup-jobs}>>
+
+[discrete]
+[[rollup-data-endpoint]]
+==== Data
+
+* <<rollup-get-rollup-caps,Get rollup capabilities>>
+* <<rollup-get-rollup-index-caps,Get rollup index capabilities>>
+
+[discrete]
+[[rollup-search-endpoint]]
+==== Search
+
+* <<rollup-search,Rollup search>>
+
+include::apis/rollup-api.asciidoc[]
+include::apis/put-job.asciidoc[]
+include::apis/delete-job.asciidoc[]
+include::apis/get-job.asciidoc[]
+include::apis/rollup-caps.asciidoc[]
+include::apis/rollup-index-caps.asciidoc[]
+include::apis/rollup-search.asciidoc[]
+include::apis/start-job.asciidoc[]
+include::apis/stop-job.asciidoc[]
+
+endif::[]
+ifndef::permanently-unreleased-branch[]
+
+[discrete]
+[[rollup-jobs-endpoint]]
+=== Jobs
+
+* <<rollup-put-job,Create>> or <<rollup-delete-job,delete {rollup-jobs}>>
+* <<rollup-start-job,Start>> or <<rollup-stop-job,stop {rollup-jobs}>>
+* <<rollup-get-job,Get {rollup-jobs}>>
+
+[discrete]
+[[rollup-data-endpoint]]
+=== Data
+
+* <<rollup-get-rollup-caps,Get rollup capabilities>>
+* <<rollup-get-rollup-index-caps,Get rollup index capabilities>>
+
+[discrete]
+[[rollup-search-endpoint]]
+=== Search
+
+* <<rollup-search,Rollup search>>
+
+
+include::apis/put-job.asciidoc[]
+include::apis/delete-job.asciidoc[]
+include::apis/get-job.asciidoc[]
+include::apis/rollup-caps.asciidoc[]
+include::apis/rollup-index-caps.asciidoc[]
+include::apis/rollup-search.asciidoc[]
+include::apis/start-job.asciidoc[]
+include::apis/stop-job.asciidoc[]
+
+endif::[]