Users have complained for a while that Swift's ETags don't match the
expected RFC formats. We've resisted fixing this for just as long,
worrying that the fix would break innumerable clients that expect the
value to be a hex-encoded MD5 digest and *nothing else*.
But, users keep asking for it, and some consumers (including some CDNs)
break if we *don't* have quoted etags -- so, let's make it an option.
With this middleware, Swift users can set metadata per-account or even
per-container to explicitly request RFC compliant etags or not. Swift
operators also get an option to change the default behavior
cluster-wide; it defaults to the old, non-compliant format.
See also:
- https://tools.ietf.org/html/rfc2616#section-3.11
- https://tools.ietf.org/html/rfc7232#section-2.3
Closes-Bug: 1099087
Closes-Bug: 1424614
Co-Authored-By: Tim Burke <tim.burke@gmail.com>
Change-Id: I380c6e34949d857158e11eb428b3eda9975d855d
27fd97cef9