Configuring Calling Format for S3 URLs

[k-anon]

Debugging alleged connection issues with a secure site that uses S3 storage has revealed that in some instances, the default SubdomainCallingFormat used by boto.s3.connection.S3Connection for S3 bucket URLs can trip SSL certificate authentication in browsers, since wildcarded subdomains are being deprecated (http://tools.ietf.org/html/rfc6125#section-7.2). In some cases over HTTPS, this could trigger a browser warning, and Internet Explorer 10 on Windows 8 can even hide the issue behind an opaque "Connection Error."

For this reason, I believe the default (indeed, for boto as well) should be boto.s3.connection.OrdinaryCallingFormat. I have therefore taken an opinionated approach here of using OrdinaryCallingFormat by default when calling S3Connection and allowing the user to configure the calling format otherwise using setting import string in settings.URL_CALLING_FORMAT. For more details, please review the documentation update and the addition to S3BotoStorage.__init__().