The proxy_logging middleware needs an X-Backend-Storage-Policy-Index
header to populate the storage policy field in logs, and will look in
both request and response headers to find it.
Previously, the s3api middleware would indiscriminately copy the
X-Backend-Storage-Policy-Index from swift backend requests into the
S3Request headers [1]. This works for logging but causes the header
to leak between backend requests [2] and break mixed policy
multipart uploads. This patch sets the X-Backend-Storage-Policy-Index
header on s3api responses rather than requests.
Additionally, the middleware now looks for the
X-Backend-Storage-Policy-Index header in the swift backend request
*and* response headers, in the same way that proxy_logging would
(preferring a response header over a request header). This means that
a policy index is now logged for bucket requests, which only have
X-Backend-Storage-Policy-Index header in their response headers.
The s3api adds the value from the *final* backend request/response
pair to its response headers. Returning the policy index from the
final backend request/response is consistent with swift.backend_path
being set to that backend request's path i.e. proxy_logging will log
the correct policy index for the logged path.
The FakeSwift helper no longer looks in registered object responses
for an X-Backend-Storage-Policy-Index header to update an object
request. Real Swift object responses do not have an
X-Backend-Storage-Policy-Index header. By default, FakeSwift will now
update *all* object requests with an X-Backend-Storage-Policy-Index as
follows:
 - If a matching container HEAD response has been registered then
 any X-Backend-Storage-Policy-Index found with that is used.
 - Otherwise the default policy index is used.
Furthermore, FakeSwift now adds the X-Backend-Storage-Policy-Index
header to the request *after* the request has been captured. Tests
using FakeSwift.calls_wth_headers() to make assertions about captured
headers no longer need to make allowance for the header that FakeSwift
added.
Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>
Closes-Bug: #2038459
[1] Related-Change: I5fe5ab31d6b2d9f7b6ecb3bfa246433a78e54808
[2] Related-Change: I40b252446b3a1294a5ca8b531f224ce9c16f9aba
Change-Id: I2793e335a08ad373c49cbbe6759d4e97cc420867