Before this patch, the proxy ObjectController supported sending
metadata from the proxy server to object servers in "footers" that
trail the body of HTTP PUT requests, but this support was for EC
policies only. The encryption feature requires that footers are sent
with both EC and replicated policy requests in order to persist
encryption specific sysmeta, and to override container update headers
with an encrypted Etag value.
This patch:
- Moves most of the functionality of ECPutter into a generic Putter
class that is used for replicated object PUTs without footers.
- Creates a MIMEPutter subclass to support multipart and multiphase
behaviour required for any replicated object PUT with footers and
all EC PUTs.
- Modifies ReplicatedObjectController to use Putter objects in place
of raw connection objects.
- Refactors the _get_put_connections method and _put_connect_node methods
so that more code is in the BaseObjectController class and therefore
shared by [EC|Replicated]ObjectController classes.
- Adds support to call a callback that middleware may have placed
in the environ, so the callback can set footers. The
x-object-sysmeta-ec- namespace is reserved and any footer values
set by middleware in that namespace will not be forwarded to
object servers.
In addition this patch enables more than one value to be added to the
X-Backend-Etag-Is-At header. This header is used to point to an
(optional) alternative sysmeta header whose value should be used when
evaluating conditional requests with If-[None-]Match headers. This is
already used with EC policies when the ECObjectController has
calculated the actual body Etag and sent it using a footer
(X-Object-Sysmeta-EC-Etag). X-Backend-Etag-Is-At is in that case set
to X-Object-Sysmeta-Ec-Etag so as to point to the actual body Etag
value rather than the EC fragment Etag.
Encryption will also need to add a pointer to an encrypted Etag value.
However, the referenced sysmeta may not exist, for example if the
object was created before encryption was enabled. The
X-Backend-Etag-Is-At value is therefore changed to support a list of
possible locations for alternate Etag values. Encryption will place
its expected alternative Etag location on this list, as will the
ECObjectController, and the object server will look for the first
object metadata to match an entry on the list when matching
conditional requests. That way, if the object was not encrypted then
the object server will fall through to using the EC Etag value, or in
the case of a replicated policy will fall through to using the normal
Etag metadata.
If your proxy has a third-party middleware that uses X-Backend-Etag-Is-At
and it upgrades before an object server it's talking to then conditional
requests may be broken.
UpgradeImpact
Co-Authored-By: Alistair Coles <alistair.coles@hpe.com>
Co-Authored-By: Thiago da Silva <thiago@redhat.com>
Co-Authored-By: Samuel Merritt <sam@swiftstack.com>
Co-Authored-By: Kota Tsuyuzaki <tsuyuzaki.kota@lab.ntt.co.jp>
Closes-Bug: #1594739
Change-Id: I12a6e41150f90de746ce03623032b83ed1987ee1
03b762e80a