Allow X-History-Location versioned_writes

Versioned Objects in Swift now use a middleware that is added to the
pipeline instead of the "allow_versions" in the container config. These
have 2 different Headers, so to prevent "X-Versions-Location" from not
working the "allow_versions" in the container config is left in place.

This patch adds the middleware by default and sets the Versioned Objects
support to be on. This is the upstream default and the deployer would
still need to set the "X-History-Location" header on a container to
utilise the feature.

Change-Id: I88811fd77fad8d2241448ca5ffb565fa7d704a00

defaults/main.yml

@@ -76,6 +76,7 @@ swift_middleware_list:
   - account-quotas
   - slo
   - dlo
+  - versioned_writes
   - proxy-logging
   - proxy-server
 

releasenotes/notes/swift-versioned-writes-middleware-0b529e3cf2fb493d.yaml

@@ -0,0 +1,8 @@
+---
+features:
+  - Swift ``versioned_writes`` middleware is added to the
+    pipeline by default. Additionally the
+    ``allow_versioned_writes`` settings in the middleware
+    configuration is set to ``True``. This follows the
+    Swift defaults, and enables the use of the
+    ``X-History-Location`` metadata Header.

templates/proxy-server.conf.j2

@@ -172,6 +172,10 @@ use = egg:swift#slo
 [filter:dlo]
 use = egg:swift#dlo
 
+[filter:versioned_writes]
+use = egg:swift#versioned_writes
+allow_versioned_writes = True
+
 [filter:account-quotas]
 use = egg:swift#account_quotas