openstack-ceilometer-api service fails to start after upgrading from OSP 6 to 7

Issue

• After upgrading from Juno to Kilo, the "openstack-ceilometer-api" service fails to start on the Controller node.
• The following error can be seen in the ceilometer-api log:

2015-10-20 05:51:43.207 2338 CRITICAL ceilometer [-] ScannerError: mapping values are not allowed here
  in "<string>", line 38, column 19:
              interval: 600
                      ^
2015-10-20 05:51:43.207 2338 TRACE ceilometer Traceback (most recent call last):
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/bin/ceilometer-api", line 10, in <module>
2015-10-20 05:51:43.207 2338 TRACE ceilometer     sys.exit(main())
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/cmd/api.py", line 23, in main
2015-10-20 05:51:43.207 2338 TRACE ceilometer     app.build_server()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/api/app.py", line 128, in build_server
2015-10-20 05:51:43.207 2338 TRACE ceilometer     app = load_app()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/api/app.py", line 124, in load_app
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return deploy.loadapp("config:" + cfg_file)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 247, in loadapp
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return loadobj(APP, uri, name=name, **kw)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 272, in loadobj
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return context.create()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 710, in create
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return self.object_type.invoke(self)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 203, in invoke
2015-10-20 05:51:43.207 2338 TRACE ceilometer     app = context.app_context.create()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 710, in create
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return self.object_type.invoke(self)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 146, in invoke
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return fix_call(context.object, context.global_conf, **context.local_conf)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/paste/deploy/util.py", line 56, in fix_call
2015-10-20 05:51:43.207 2338 TRACE ceilometer     val = callable(*args, **kw)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/api/app.py", line 150, in app_factory
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return VersionSelectorApplication()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/api/app.py", line 104, in __init__
2015-10-20 05:51:43.207 2338 TRACE ceilometer     self.v2 = setup_app(pecan_config=pc)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/api/app.py", line 66, in setup_app
2015-10-20 05:51:43.207 2338 TRACE ceilometer     hooks.PipelineHook(),
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/api/hooks.py", line 79, in __init__
2015-10-20 05:51:43.207 2338 TRACE ceilometer     self.pipeline_manager = pipeline.setup_pipeline()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/pipeline.py", line 697, in setup_pipeline
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return _setup_pipeline_manager(cfg_file, transformer_manager)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib/python2.7/site-packages/ceilometer/pipeline.py", line 678, in _setup_pipeline_manager
2015-10-20 05:51:43.207 2338 TRACE ceilometer     pipeline_cfg = yaml.safe_load(data)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/__init__.py", line 93, in safe_load
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return load(stream, SafeLoader)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/__init__.py", line 71, in load
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return loader.get_single_data()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/constructor.py", line 37, in get_single_data
2015-10-20 05:51:43.207 2338 TRACE ceilometer     node = self.get_single_node()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 36, in get_single_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     document = self.compose_document()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 55, in compose_document
2015-10-20 05:51:43.207 2338 TRACE ceilometer     node = self.compose_node(None, None)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 84, in compose_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     node = self.compose_mapping_node(anchor)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 133, in compose_mapping_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     item_value = self.compose_node(node, item_key)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 82, in compose_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     node = self.compose_sequence_node(anchor)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 111, in compose_sequence_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     node.value.append(self.compose_node(node, index))
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 84, in compose_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     node = self.compose_mapping_node(anchor)
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/composer.py", line 127, in compose_mapping_node
2015-10-20 05:51:43.207 2338 TRACE ceilometer     while not self.check_event(MappingEndEvent):
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/parser.py", line 98, in check_event
2015-10-20 05:51:43.207 2338 TRACE ceilometer     self.current_event = self.state()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/parser.py", line 428, in parse_block_mapping_key
2015-10-20 05:51:43.207 2338 TRACE ceilometer     if self.check_token(KeyToken):
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/scanner.py", line 116, in check_token
2015-10-20 05:51:43.207 2338 TRACE ceilometer     self.fetch_more_tokens()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/scanner.py", line 220, in fetch_more_tokens
2015-10-20 05:51:43.207 2338 TRACE ceilometer     return self.fetch_value()
2015-10-20 05:51:43.207 2338 TRACE ceilometer   File "/usr/lib64/python2.7/site-packages/yaml/scanner.py", line 580, in fetch_value
2015-10-20 05:51:43.207 2338 TRACE ceilometer     self.get_mark())
2015-10-20 05:51:43.207 2338 TRACE ceilometer ScannerError: mapping values are not allowed here
2015-10-20 05:51:43.207 2338 TRACE ceilometer   in "<string>", line 38, column 19:
2015-10-20 05:51:43.207 2338 TRACE ceilometer               interval: 600
2015-10-20 05:51:43.207 2338 TRACE ceilometer                       ^
2015-10-20 05:51:43.207 2338 TRACE ceilometer