Docs create snapshot api docs 7.8 (#58694)

* [DOCS] Adding create index snapshot API docs (#58519)

* Adding create index snapshot API page.
* Condense API description.
* Remove parameter from query.
* Add POST method and remove `-name` from the snapshot variable.
* Expand description of `<snapshot>`.
* Add data streams to introduction and expand the overall description.
* Add support for data streams.
* Add support for data streams.
* Add data stream and reference for "point-in-time view".
* Add data streams.
* Change `my_backup` to `my_repository`.
* Add description of boolean options for `wait_for_completion` parameter.
* Change command --> response
* Clarify `indices` parameter description
* Update `ignore-unavailable` parameter description
* Reword example description
* Remove "index" from API name
* Incorporating review comments from James R.
* Adding a much better request + response
* Clarify `include_global_state` description
* Incorporating additional edits.
* Changing my_backup to my_repository in example.
* Update snippet test to avoid failures
* Update TESTRESPONSE snippets
* Remove errant space
* Removing the  parameter per reviewer comments
* Removing mentions of data streams for 7.8.
* Removing data_streams  from the code example.

docs/reference/snapshot-restore/apis/create-snapshot-api.asciidoc

@@ -0,0 +1,188 @@
+[[create-snapshot-api]]
+=== Create snapshot API
+++++
+<titleabbrev>Create snapshot</titleabbrev>
+++++
+
+Takes a <<snapshot-restore,snapshot>> of a cluster or specified
+indices.
+
+////
+[source,console]
+-----------------------------------
+PUT /_snapshot/my_repository
+{
+  "type": "fs",
+  "settings": {
+    "location": "my_backup_location"
+  }
+}
+-----------------------------------
+// TESTSETUP
+////
+
+[source,console]
+-----------------------------------
+PUT /_snapshot/my_repository/my_snapshot
+-----------------------------------
+// TEST[s/my_snapshot/my_snapshot?wait_for_completion=true/]
+
+[[create-snapshot-api-request]]
+==== {api-request-title}
+
+`PUT /_snapshot/<repository>/<snapshot>`
+
+`POST /_snapshot/<repository>/<snapshot>`
+
+[[create-snapshot-api-desc]]
+==== {api-description-title}
+
+You can use the create snapshot API to create a <<snapshot-restore,snapshot>>, which is a
+backup taken from a running {es} cluster.
+
+By default, a snapshot includes all open indices in the
+cluster, as well as the cluster state.  You can change this behavior by
+specifying a list of indices to back up in the body of the
+snapshot request.
+
+NOTE: You must register a snapshot before performing snapshot and restore operations. Use the <<put-snapshot-repo-api,put snapshot repository API>> to register new repositories and update existing ones.
+
+The snapshot process is incremental. When creating a snapshot, {es} analyzes the list of files that are already stored in the repository and copies only files that were created or changed since the last snapshot. This process allows multiple snapshots to be preserved in the repository in a compact form.
+
+The snapshot process is executed in non-blocking fashion, so all indexing and searching operations can run concurrently against the data stream or index that {es} is snapshotting. Only one snapshot process can run in the cluster at any time.
+
+A snapshot represents a point-in-time view of the moment when the snapshot was created. No records that were added to a data stream or index after the snapshot process started will be present in the snapshot.
+
+For primary shards that have not been started and are not currently relocating, the snapshot process starts immediately. If shards are in the process of starting or relocating, {es} waits for these processes to complete before taking a snapshot.
+
+IMPORTANT: While a snapshot of a particular shard is being created, this shard cannot be moved to another node. Relocating a shard during the snapshot process can interfere with rebalancing and allocation filtering. {es} can move a shard to another node (according to the current allocation filtering settings and rebalancing algorithm) only after the snapshot process completes.
+
+Besides creating a copy of each data stream and index, the snapshot process can also store global cluster metadata, including persistent cluster settings and templates. The transient settings and registered snapshot repositories are not stored as part of the snapshot.
+
+[[create-snapshot-api-path-params]]
+==== {api-path-parms-title}
+
+`<repository>`::
+(Required, string)
+Name of the repository to create a snapshot in.
+
+`<snapshot>`::
+(Required, string)
+Name of the snapshot to create. This name must be unique in the snapshot repository.
+
+[role="child_attributes"]
+[[create-snapshot-api-request-body]]
+==== {api-request-body-title}
+
+`ignore_unavailable`::
+(Optional, boolean)
+If `false`, the request returns an error for any data stream or index that is missing or closed. Defaults to `false`.
++
+If `true`, the request ignores and indices in `indices` that are missing or closed.
+
+`indices`::
+(Optional, string)
+A comma-separated list of indices to include in the snapshot.
+<<multi-index,Multi-index syntax>> is supported.
++
+By default, a snapshot includes all indices in the cluster. If this
+argument is provided, the snapshot only includes the specified clusters.
+
+`include_global_state`::
++
+--
+(Optional, boolean)
+If `true`, the current cluster state is included in the snapshot.
+Defaults to `true`.
+
+The cluster state includes:
+
+* Persistent cluster settings
+* Index templates
+* Legacy index templates
+* Ingest pipelines
+* {ilm-init} lifecycle policies
+--
++
+IMPORTANT: By default, the entire snapshot will fail if one or more indices included in the snapshot do not have all primary shards available. You can change this behavior by setting <<create-snapshot-api-partial,`partial`>> to `true`.
+
+include::{es-repo-dir}/rest-api/common-parms.asciidoc[tag=master-timeout]
+
+`metadata`::
+(Optional, string)
+Attaches arbitrary metadata to the snapshot, such as a record of who took the snapshot, why it was taken, or any other useful data. Metadata must be less than 1024 bytes.
+
+[[create-snapshot-api-partial]]
+`partial`::
+(Optional, boolean)
+If `false`, the entire snapshot will fail if one or more indices included in the snapshot do not have all primary shards available. Defaults to `false`.
++
+If `true`, allows taking a partial snapshot of indices with unavailable shards.
+
+`wait_for_completion`::
+(Optional, boolean)
+If `true`, the request returns a response when the snapshot is complete.
+If `false`, the request returns a response when the snapshot initializes.
+Defaults to `false`.
++
+NOTE: During snapshot initialization, information about all
+previous snapshots is loaded into memory. In large repositories, this load time can cause requests to take several seconds (or even minutes) to return a response, even if the `wait_for_completion` parameter is `false`.
+
+[[create-snapshot-api-example]]
+==== {api-examples-title}
+
+The following request takes a snapshot of `index_1` and `index_2`.
+
+[source,console]
+-----------------------------------
+PUT /_snapshot/my_repository/snapshot_2?wait_for_completion=true
+{
+  "indices": "index_1,index_2",
+  "ignore_unavailable": true,
+  "include_global_state": false,
+  "metadata": {
+    "taken_by": "user123",
+    "taken_because": "backup before upgrading"
+  }
+}
+-----------------------------------
+
+The API returns the following response:
+
+[source,console-result]
+----
+{
+  "snapshot": {
+    "snapshot": "snapshot_2",
+    "uuid": "vdRctLCxSketdKb54xw67g",
+    "version_id": <version_id>,
+    "version": <version>,
+    "indices": [],
+    "include_global_state": false,
+    "metadata": {
+      "taken_by": "user123",
+      "taken_because": "backup before upgrading"
+    },
+    "state": "SUCCESS",
+    "start_time": "2020-06-25T14:00:28.850Z",
+    "start_time_in_millis": 1593093628850,
+    "end_time": "2020-06-25T14:00:28.850Z",
+    "end_time_in_millis": 1593094752018,
+    "duration_in_millis": 0,
+    "failures": [],
+    "shards": {
+      "total": 0,
+      "failed": 0,
+      "successful": 0
+    }
+  }
+}
+----
+// TESTRESPONSE[s/"uuid": "vdRctLCxSketdKb54xw67g"/"uuid": $body.snapshot.uuid/]
+// TESTRESPONSE[s/"version_id": <version_id>/"version_id": $body.snapshot.version_id/]
+// TESTRESPONSE[s/"version": <version>/"version": $body.snapshot.version/]
+// TESTRESPONSE[s/"start_time": "2020-06-25T14:00:28.850Z"/"start_time": $body.snapshot.start_time/]
+// TESTRESPONSE[s/"start_time_in_millis": 1593093628850/"start_time_in_millis": $body.snapshot.start_time_in_millis/]
+// TESTRESPONSE[s/"end_time": "2020-06-25T14:00:28.850Z"/"end_time": $body.snapshot.end_time/]
+// TESTRESPONSE[s/"end_time_in_millis": 1593094752018/"end_time_in_millis": $body.snapshot.end_time_in_millis/]
+// TESTRESPONSE[s/"duration_in_millis": 0/"duration_in_millis": $body.snapshot.duration_in_millis/]

docs/reference/snapshot-restore/apis/snapshot-restore-apis.asciidoc

@@ -22,9 +22,14 @@ content may not be included yet.
 * <<put-snapshot-repo-api,Put snapshot repository>>
 * <<verify-snapshot-repo-api,Verify snapshot repository>>
 
+[discrete]
+[[snapshot-management-apis]]
+=== Snapshot management APIs
+* <<create-snapshot-api,Create snapshot>>
 
+include::create-snapshot-api.asciidoc[]
 include::clean-up-repo-api.asciidoc[]
 include::delete-repo-api.asciidoc[]
 include::get-repo-api.asciidoc[]
 include::put-repo-api.asciidoc[]
-include::verify-repo-api.asciidoc[]
+include::verify-repo-api.asciidoc[]