Allow setting signature version to S3 uploader (#537)

* Allow setting signature version to S3

* Add missing docs

docs/settings.rst

@@ -282,6 +282,18 @@ Links are generated as presigned urls for security
    EXPLORER_S3_LINK_EXPIRATION = 3600
 
 
+S3 signature version
+********************
+
+The signature version when signing requests.
+As of ``boto3`` version 1.13.21 the default signature version used for generating presigned urls is still ``v2``.
+To be able to access your s3 objects in all regions through presigned urls, explicitly set this to ``s3v4``.
+
+.. code-block:: python
+
+   EXPLORER_S3_SIGNATURE_VERSION = 's3v4'
+
+
 From email
 **********
 

explorer/app_settings.py

@@ -133,6 +133,7 @@
 S3_REGION = getattr(settings, "EXPLORER_S3_REGION", "us-east-1")
 S3_ENDPOINT_URL = getattr(settings, "EXPLORER_S3_ENDPOINT_URL", None)
 S3_DESTINATION = getattr(settings, "EXPLORER_S3_DESTINATION", '')
+S3_SIGNATURE_VERSION = getattr(settings, "EXPLORER_S3_SIGNATURE_VERSION", 'v2')
 
 UNSAFE_RENDERING = getattr(settings, "EXPLORER_UNSAFE_RENDERING", False)
 

explorer/utils.py

@@ -193,10 +193,14 @@ def get_valid_connection(alias=None):
 
 def get_s3_bucket():
     import boto3
+    from botocore.client import Config
     kwargs = {
         'aws_access_key_id': app_settings.S3_ACCESS_KEY,
         'aws_secret_access_key': app_settings.S3_SECRET_KEY,
-        'region_name': app_settings.S3_REGION
+        'region_name': app_settings.S3_REGION,
+        'config': Config(
+            signature_version=app_settings.S3_SIGNATURE_VERSION
+        )
     }
     if app_settings.S3_ENDPOINT_URL:
         kwargs['endpoint_url'] = app_settings.S3_ENDPOINT_URL