Better default value for domain in swift config

The default value of domain id as 'default' set in the Java code is not
always ideal.

This is not totally ideal either (see the comments) but helps somewhat.

Change-Id: Ib5433ee441fb4d63f76e43e0c449e97d197a5b18

releasenotes/notes/hadoop-swift-domain-fix-c1dfdf6c52b5aa25.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - Hadoop is now better configured to use the proper Keystone domain
+    for interaction with Swift; previously the 'default' domain may
+    have been incorrectly used.

sahara/swift/swift_helper.py

@@ -60,6 +60,16 @@ def get_swift_configs():
             conf['value'] = retrieve_tenant()
         if CONF.os_region_name and conf['name'] == HADOOP_SWIFT_REGION:
             conf['value'] = CONF.os_region_name
+        if conf['name'] == HADOOP_SWIFT_DOMAIN_NAME:
+            # NOTE(jfreud): Don't be deceived here... Even though there is an
+            # attribute provided by context called domain_name, it is used for
+            # domain scope, and hadoop-swiftfs always authenticates using
+            # project scope. The purpose of the setting below is to override
+            # the default value for project domain and user domain, domain id
+            # as 'default', which may not always be correct.
+            # TODO(jfreud): When hadoop-swiftfs allows it, stop hoping that
+            # project_domain_name is always equal to user_domain_name.
+            conf['value'] = context.current().project_domain_name
 
     result = [cfg for cfg in configs if cfg['value']]
     LOG.info("Swift would be integrated with the following "