Example of nova credential command

If your credential settings are correct you are going to see this output

root@server:~# set | grep OS_
OS_AUTH_SYSTEM=rackspace_uk
OS_AUTH_URL=https://lon.identity.api.rackspacecloud.com/v2.0/
OS_NO_CACHE=1
OS_PASSWORD=777
OS_REGION_NAME=LON
OS_TENANT_NAME=777
OS_USERNAME=777

root@server:~# nova credentials
+------------------------+---------------------------------------------------------------------------------------+       22:51:35
| User Credentials       | Value                                                                                 |
+------------------------+---------------------------------------------------------------------------------------+
| RAX-AUTH:defaultRegion |                                                                                       |
| id                     | 777                                                                                 |
| name                   | name                                                                       |
| roles                  | [{u'description': u'User Admin Role.', u'id': u'3', u'name': u'identity:user-admin'}] |
+------------------------+---------------------------------------------------------------------------------------+
+---------+--------------------------------------------+
| Token   | Value                                      |
+---------+--------------------------------------------+
| expires | 2012-10-24T13:21:47.000+01:00              |
| id      | f6e9c367-7777-7777-7777-777777777777       |
| tenant  | {u'id': u'777', u'name': u'777'} |
+---------+--------------------------------------------+

If your credentials are wrong you will see this one instead

root@server:~# nova credentials
ERROR: Invalid OpenStack Nova credentials.

root@server:~# nova --debug credentials

REQ: curl -i https://lon.identity.api.rackspacecloud.com/v2.0/tokens -X POST -H "Content-Type: application/json" -H "Accept: application/json" -H "User-Agent: python-novaclient" -d '{"auth": {"RAX-KSKEY:apiKeyCredentials": {"username": "777", "apiKey": "777", "tenantName": "777"}}}'

connect: (lon.identity.api.rackspacecloud.com, 443)
send: 'POST /v2.0/tokens HTTP/1.1\r\nHost: lon.identity.api.rackspacecloud.com\r\nContent-Length: 154\r\ncontent-type: application/json\r\naccept-encoding: gzip, deflate\r\naccept: application/json\r\nuser-agent: python-novaclient\r\n\r\n{"auth": {"RAX-KSKEY:apiKeyCredentials": {"username": "777", "apiKey": "777", "tenantName": "777"}}}'
reply: 'HTTP/1.1 401 Unauthorized\r\n'
header: Server: nginx/0.8.55
header: Date: Tue, 23 Oct 2012 22:55:15 GMT
header: Content-Type: application/json
header: Transfer-Encoding: chunked
header: Connection: keep-alive
header: Content-Encoding: gzip
header: response-source: cloud-auth
header: vary: Accept, Accept-Encoding, X-Auth-Token
header: VIA: 1.0 Repose (Repose/2.3.5)
RESP:{'status': '401', 'content-length': '73', 'via': '1.0 Repose (Repose/2.3.5)', 'response-source': 'cloud-auth', 'transfer-encoding': 'chunked', 'vary': 'Accept, Accept-Encoding, X-Auth-Token', 'server': 'nginx/0.8.55', 'connection': 'keep-alive', '-content-encoding': 'gzip', 'date': 'Tue, 23 Oct 2012 22:55:15 GMT', 'content-type': 'application/json'} {"unauthorized":{"code":401,"message":"Username or api key is invalid"}}

DEBUG (shell:534) Invalid OpenStack Nova credentials.
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/novaclient/shell.py", line 531, in main
    OpenStackComputeShell().main(sys.argv[1:])
  File "/usr/local/lib/python2.7/dist-packages/novaclient/shell.py", line 463, in main
    raise exc.CommandError("Invalid OpenStack Nova credentials.")
CommandError: Invalid OpenStack Nova credentials.
ERROR: Invalid OpenStack Nova credentials.