Use S3 from community (#7920)

Bring `S3PrivateBucketMixin` into community code so we can share more code with
commercial and between our community classes as well.

Author: humitos

readthedocs/storage/mixins.py

@@ -24,3 +24,15 @@ def url(self, *args, **kwargs):
             url = urlunsplit(parts)
 
         return url
+
+
+class S3PrivateBucketMixin:
+
+    """Make the bucket private and use auth querystring."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        self.bucket_acl = 'private'
+        self.default_acl = 'private'
+        self.querystring_auth = True

readthedocs/storage/s3_storage.py

@@ -15,7 +15,8 @@
 from storages.backends.s3boto3 import S3Boto3Storage
 
 from readthedocs.builds.storage import BuildMediaStorageMixin
-from readthedocs.storage.mixins import OverrideHostnameMixin
+
+from .mixins import OverrideHostnameMixin, S3PrivateBucketMixin
 
 
 class S3BuildMediaStorage(BuildMediaStorageMixin, OverrideHostnameMixin, S3Boto3Storage):
@@ -35,7 +36,7 @@ def __init__(self, *args, **kwargs):
             )
 
 
-class S3BuildCommandsStorage(S3Boto3Storage):
+class S3BuildCommandsStorage(S3PrivateBucketMixin, S3Boto3Storage):
 
     """An AWS S3 Storage backend for build commands."""
 
@@ -50,10 +51,6 @@ def __init__(self, *args, **kwargs):
                 'Ensure S3_BUILD_COMMANDS_STORAGE_BUCKET is defined.',
             )
 
-        self.bucket_acl = 'private'
-        self.default_acl = 'private'
-        self.querystring_auth = True
-
 
 class S3StaticStorage(OverrideHostnameMixin, ManifestFilesMixin, S3Boto3Storage):
 
@@ -80,7 +77,7 @@ def __init__(self, *args, **kwargs):
         self.querystring_auth = False
 
 
-class S3BuildEnvironmentStorage(BuildMediaStorageMixin, S3Boto3Storage):
+class S3BuildEnvironmentStorage(S3PrivateBucketMixin, BuildMediaStorageMixin, S3Boto3Storage):
 
     bucket_name = getattr(settings, 'S3_BUILD_ENVIRONMENT_STORAGE_BUCKET', None)
 
@@ -92,7 +89,3 @@ def __init__(self, *args, **kwargs):
                 'AWS S3 not configured correctly. '
                 'Ensure S3_BUILD_ENVIRONMENT_STORAGE_BUCKET is defined.',
             )
-
-        self.bucket_acl = 'private'
-        self.default_acl = 'private'
-        self.querystring_auth = True