feat(docs): s3-presigned-urls.rst updated, s3-client-context-manager.…

…rst added

- s3-presigned-urls.rst updated with passing the original file names and extensions to presigned URLs through `Content-Disposition` HTTP-header;
- context manager wrapper for pytonic-way client usage example added;

docs/source/guide/s3-client-context-manager.rst

@@ -0,0 +1,64 @@
+.. Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+
+   This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0
+   International License (the "License"). You may not use this file except in compliance with the
+   License. A copy of the License is located at http://creativecommons.org/licenses/by-nc-sa/4.0/.
+
+   This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+   either express or implied. See the License for the specific language governing permissions and
+   limitations under the License.
+
+
+###############
+S3 Client Context Manager
+###############
+
+Following the pythonic-way, you may want to flexibly and easily manage resource release using a context manager for
+the `boto3.client` instances you create.
+
+The following is an example of creating a simple context manager for an S3 client:
+
+.. code-block:: python
+
+    from contextlib import contextmanager
+    from typing import Optional
+
+    import boto3
+
+
+    @contextmanager
+    def s3_client(**kwargs):
+        client = None
+        try:
+            client = boto3.client("s3", **kwargs)
+            yield client
+        finally:
+            if client:
+                client.close()
+
+
+Using the `s3_client` context manager you can easily create service functions that implement the necessary
+actions with the storage.
+
+.. code-block:: python
+
+    def s3_get_object(
+        key: str,
+        # Your global constants from project settings here.
+        bucket_name: str = AWS_BUCKET_NAME,
+        aws_access_key_id=AWS_ACCESS_KEY_ID,
+        aws_secret_access_key=AWS_SECRET_ACCESS_KEY,
+        endpoint_url=AWS_ENDPOINT_URL,
+    ):
+    with s3_client(
+            aws_access_key_id=aws_access_key_id,
+            aws_secret_access_key=aws_secret_access_key,
+            endpoint_url=endpoint_url,
+    ) as s3_cli:
+        return s3_cli.get_object(Bucket=bucket_name, Key=key)
+
+
+    # Usage example:
+    key = "path/to/somefile"
+    s3_obj = s3_get_object(key)
+

docs/source/guide/s3-examples.rst

@@ -39,3 +39,4 @@ services.
    s3-example-static-web-host
    s3-example-configuring-buckets
    s3-example-privatelink
+   s3-client-context-manager

docs/source/guide/s3-presigned-urls.rst

@@ -70,6 +70,59 @@ perform a GET request.
         response = requests.get(url)
 
 
+Pass the original file names and extensions to presigned URLs
+===================================================
+
+If you are using S3 as an object store for your web service users' files, a common solution is to store
+anonymized "raw" files like `file.bin` in S3, and the original file names and extensions in a relational database.
+
+In this scenario, unless you explicitly specify a `Content-Disposition` HTTP-header, your users will receive
+“raw” files using generated presigned urls.
+
+.. code-block:: python
+
+    import logging
+    import boto3
+    from botocore.exceptions import ClientError
+
+
+    def create_presigned_url(bucket_name, object_name, expiration=3600,
+                             request_content_disposition: str | None = None):
+        """Generate a presigned URL to share an S3 object
+
+        :param bucket_name: string
+        :param object_name: string
+        :param expiration: Time in seconds for the presigned URL to remain valid
+        :param request_content_disposition: HTTP header that tells the browser the name and extension of the original file.
+        :return: Presigned URL as string. If error, returns None.
+        """
+
+        # Generate a presigned URL for the S3 object
+        s3_client = boto3.client('s3')
+        params = {"Bucket": bucket_name, "Key": object_name}
+        if request_content_disposition:
+            params["ResponseContentDisposition"] = request_content_disposition
+        try:
+            response = s3_client.generate_presigned_url('get_object',
+                                                        Params=params,
+                                                        ExpiresIn=expiration)
+        except ClientError as e:
+            logging.error(e)
+            return None
+
+        # The response contains the presigned URL
+        return response
+
+By applying these changes, you can generate links with the original file names:
+.. code-block:: python
+
+    from urllib.parse import quote
+
+    original_filename = 'demo_file.txt'
+    url = create_presigned_url('amzn-s3-demo-bucket', 'OBJECT_NAME',
+                               request_content_disposition=f'attachment; filename="{quote(original_filename)}"')
+
+
 Using presigned URLs to perform other S3 operations
 ===================================================