I want modify Ceilometer to add some more features. I am using DevStack on Ubuntu12.04 based on stable/havana. My localrc is as follows.

ENABLED_SERVICES+=,ceilometer-acompute,ceilometer-acentral,ceilometer-collector,ceilometer-api

I can login to Horizon via Firefox, and "keystone service-list" also works. But when I type "ceilometer -d meter-list", it claims

stack@peer:~/havana/devstack$ ceilometer -d meter-list 
WARNING (http:172) Request returned failure status.
Traceback (most recent call last):
  File "/usr/local/bin/ceilometer", line 10, in <module>
    sys.exit(main())
  File "/opt/stack/python-ceilometerclient/ceilometerclient/shell.py", line 335, in main
    CeilometerShell().main(args)
  File "/opt/stack/python-ceilometerclient/ceilometerclient/shell.py", line 289, in main
    args.func(client, args)
  File "/opt/stack/python-ceilometerclient/ceilometerclient/v2/shell.py", line 144, in do_meter_list
    meters = cc.meters.list(q=options.cli_to_array(args.query))
  File "/opt/stack/python-ceilometerclient/ceilometerclient/v2/meters.py", line 31, in list
    return self._list(options.build_url(path, q))
  File "/opt/stack/python-ceilometerclient/ceilometerclient/common/base.py", line 58, in _list
    resp, body = self.api.json_request('GET', url)
  File "/opt/stack/python-ceilometerclient/ceilometerclient/common/http.py", line 190, in json_request
    resp, body_iter = self._http_request(url, method, **kwargs)
  File "/opt/stack/python-ceilometerclient/ceilometerclient/common/http.py", line 173, in _http_request
    raise exc.from_response(resp, ''.join(body_iter))
ceilometerclient.exc.HTTPBadGateway: HTTPBadGateway (HTTP 502)

Anyone can help? or give me some hint? Thanks!