Ceph » rgw

The logic in preprocess is very messy, and ripe for rewrite to reflect this improvement.
1. Is $Host an exact match to the suffix lists -> path-style access; bucket name is the first path element (Client URL http://$suffix/$bucket/...)
2. Is $Host a suffix-match against lists -> subdomain access; Bucket name is $Host ~= s/${suffix}$//; (Client URL http://$bucket.$suffix/...)
3. Resolve $Host, store result as $CNameHost
4. Is $CNameHost an exact match to the suffix lists -> Vhost-style access; bucket name is $Host (Client URL http://$bucket/...)
5. Is $CNameHost a suffix match against lists -> subdomain access; bucket name is CNameHost ~= s/${suffix}$// (Client URL http://$bucket/...)
6. Fallback to use $Host as bucket (Client URL http://$bucket/...)

Phase 1 implementation (Kraken, backport to Jewel):
Add fallback to $Host if subdomain == NULL/empty at the end of the present logic.

Phase 2 implementation (Kraken):
Rewrite decision logic to support all the above cases w/ staticsites clearly.

I reviewed AWS S3, both for documentation and actual functionality (since they can differ).

This page covers what we're talking about.
http://docs.aws.amazon.com/AmazonS3/latest/dev/VirtualHosting.html#VirtualHostingCustomURLs

The CNAME DNS record should alias your domain name to the appropriate virtual hosted–style host name. For example, if your bucket name and domain name are images.johnsmith.net, the CNAME record should alias to images.johnsmith.net.s3.amazonaws.com.

www.example.com. IN CNAME www.example.com.s3.amazonaws.com.
Works in AWS-S3.
Works in Ceph-Hammer.

Based on this, we could consider disabling the rgw_resolve_cname functionality for stronger S3 functionality matching.
Works in Ceph-Jewel.

Setting the alias target to s3.amazonaws.com also works, but it may result in extra HTTP redirects

Confirmed:
www.example.com. IN CNAME s3.amazonaws.com.
Works in AWS-S3.
Does NOT work in Ceph-Hammer.
Does NOT work in Ceph-Jewel.

Because Amazon S3 sees only the original host name www.example.com and is unaware of the CNAME mapping used to resolve the request, the CNAME and the bucket name must be the same.
...
The bucket name must exactly match the host name.

This deviates from something that RGW can do:
www.example.com. IN CNAME other-bucket-name.s3.rgw.ceph.com.
Works in Ceph.
Does NOT work in S3.

Phase1 implementation available in https://github.com/ceph/ceph/pull/9354

It's critical for staticsites, but also fixes a case where AWS S3 worked and RGW did not.