snapshots clients background added for Azure and S3

deploy-manage/tools/snapshot-and-restore/azure-repository.md

@@ -12,19 +12,21 @@ products:
 
 You can use [Azure Blob storage](https://docs.microsoft.com/en-us/azure/storage/blobs/storage-blobs-introduction) as a repository for [Snapshot and restore](../snapshot-and-restore.md).
 
+{{es}} uses an internal client module to connect to Azure Blob storage, referred to in this document as the *Azure client* or the *Azure repository client*. Clients are configured through a combination of [secure settings](../../security/secure-settings.md) defined in the {{es}} keystore, and [standard settings](/deploy-manage/stack-settings.md) defined in `elasticsearch.yml`.
+
 ## Setup [repository-azure-usage]
 
 To enable Azure repositories, first configure an Azure repository client by specifying one or more settings of the form `azure.client.CLIENT_NAME.SETTING_NAME`. By default, `azure` repositories use a client named `default`, but you may specify a different client name when registering each repository.
 
-The only mandatory Azure repository client setting is `account`, which is a [secure setting](../../security/secure-settings.md) defined in the [{{es}} keystore](../../security/secure-settings.md). To provide this setting, use the `elasticsearch-keystore` tool on each node:
+The only mandatory setting for an Azure repository client is `account`, which is a [secure setting](../../security/secure-settings.md) defined in the {{es}} keystore. To provide this setting, use the `elasticsearch-keystore` tool on each node:
 
 ```sh
 bin/elasticsearch-keystore add azure.client.default.account
 ```
 
-If you adjust this setting after a node has started, call the [Nodes reload secure settings API](../../security/secure-settings.md) to reload the new value.
+If you adjust this setting after a node has started, call the [Nodes reload secure settings API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-nodes-reload-secure-settings) to reload the new value.
 
-You may define more than one client by setting their `account` values. For instance, to set the `default` client and another client called `secondary`, run the following commands on each node:
+You may define more than one client by setting their `account` values. For example, to set the `default` client and another client called `secondary`, run the following commands on each node:
 
 ```sh
 bin/elasticsearch-keystore add azure.client.default.account

deploy-manage/tools/snapshot-and-restore/s3-repository.md

@@ -18,6 +18,8 @@ If you are looking for a hosted solution of {{es}} on AWS, visit [https://www.el
 
 See [this video](https://www.youtube.com/watch?v=ACqfyzWf-xs) for a walkthrough of connecting an AWS S3 repository.
 
+{{es}} communicates with S3 through a dedicated S3 client module. Clients are configured through a combination of [secure settings](../../security/secure-settings.md) defined in the {{es}} keystore, and [standard settings](/deploy-manage/stack-settings.md) defined in `elasticsearch.yml`. If you don't provide explicit S3 client configuration, {{es}} will try to obtain credentials from the environment it's running in.
+
 ## Getting started [repository-s3-usage]
 
 To register an S3 repository, specify the type as `s3` when creating the repository. The repository defaults to using [ECS IAM Role](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-iam-roles.html) credentials for authentication. You can also use [Kubernetes service accounts](#iam-kubernetes-service-accounts) for authentication.
@@ -37,7 +39,7 @@ PUT _snapshot/my_s3_repository
 
 ## Client settings [repository-s3-client]
 
-The client that you use to connect to S3 has a number of settings available. The settings have the form `s3.client.CLIENT_NAME.SETTING_NAME`. By default, `s3` repositories use a client named `default`, but this can be modified using the [repository setting](#repository-s3-repository) `client`. For example, to use a client named `my-alternate-client`, register the repository as follows:
+The S3 client that you use to connect to S3 has a number of settings available. The settings have the form `s3.client.CLIENT_NAME.SETTING_NAME`. By default, `s3` repositories use a client named `default`, but this can be modified using the [repository setting](#repository-s3-repository) `client`. For example, to use an S3 client named `my-alternate-client`, register the repository as follows:
 
 ```console
 PUT _snapshot/my_s3_repository
@@ -50,7 +52,7 @@ PUT _snapshot/my_s3_repository
 }
 ```
 
-Most client settings can be added to the [`elasticsearch.yml`](/deploy-manage/stack-settings.md) configuration file with the exception of the secure settings, which you add to the {{es}} keystore. For more information about creating and updating the {{es}} keystore, see [Secure settings](../../security/secure-settings.md).
+Most S3 client settings can be added to the [`elasticsearch.yml`](/deploy-manage/stack-settings.md) configuration file with the exception of the secure settings, which you add to the {{es}} keystore. For more information about creating and updating the {{es}} keystore, see [Secure settings](../../security/secure-settings.md).
 
 For example, if you want to use specific credentials to access S3 then run the following commands to add these credentials to the keystore.
 
@@ -77,7 +79,7 @@ bin/elasticsearch-keystore remove s3.client.default.session_token
 
 Define the relevant secure settings in each node’s keystore before starting the node. The secure settings described here are all [reloadable](../../security/secure-settings.md#reloadable-secure-settings) so you may update the keystore contents on each node while the node is running and then call the [Nodes reload secure settings API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-nodes-reload-secure-settings) to apply the updated settings to the nodes in the cluster. After this API completes, {{es}} will use the updated setting values for all future snapshot operations, but ongoing operations may continue to use older setting values.
 
-The following list contains the available client settings. Those that must be stored in the keystore are marked as "secure" and are **reloadable**; the other settings belong in the [`elasticsearch.yml`](/deploy-manage/stack-settings.md) file.
+The following list contains the available S3 client settings. Those that must be stored in the keystore are marked as "secure" and are **reloadable**; the other settings belong in the [`elasticsearch.yml`](/deploy-manage/stack-settings.md) file.
 
 `region`
 :   Specifies the region to use. When set, determines the signing region and regional endpoint to use, unless the endpoint is overridden via the `endpoint` setting. If not set, {{es}} will attempt to determine the region automatically using the AWS SDK.