opscenter cluster metric API call - 400 error

[Aoi Kadoya <ca...@gmail.com>]

Hi,
I have upgraded my cluster to DSE 5.0.1 and Opscenter 6.0.1.
I am testing Opscenter APIs to retrieve node/cluster metrics but I get
400 errors when I throw queries as like below.

curl -vvv -H 'opscenter-session: xxxxxx' -G
'http://<opscenter>/<cluster>/metrics/<node>/data-load'

> GET /IDC/metrics/<node>/data-load HTTP/1.1
> User-Agent: curl/7.35.0
> Host: <opscenter>
> Accept: */*
> opscenter-session: xxxxxx
>
< HTTP/1.1 400 Bad Request
< Transfer-Encoding: chunked
< Date: Fri, 19 Aug 2016 20:45:36 GMT
* Server TwistedWeb/15.3.0 is not blacklisted
< Server: TwistedWeb/15.3.0
< Content-Type: application/json
< Cache-Control: max-age=0, no-cache, no-store, must-revalidate
<
* Connection #0 to host <opscenter> left intact
{"message": "unsupported operand type(s) for -: 'NoneType' and
'NoneType'", "type": "TypeError"}

I could use the same session id, opscenter ip, node ip for different
API call and I got responses with no problem but no luck with any of
metrics calls.
The error message seems complaining about "-" but I am not sure what
is wrong with the command I threw..

I am just trying some calls described here without using any query
parameters: http://docs.datastax.com/en/opscenter/6.0/api/docs/metrics.html

Can you please advice me where I should change to retrieve the metrics?

Thanks,
Aoi