[Observium] Patch to monitor by-outlet APC MasterSwitch bars

Hi,

We have recently installed some APC power bars that can be monitored by outlet (AP8653).

I have written a patch for Observium (attached) that creates sensor for each of the ports on a AP8653. The patch also includes getting the input voltage for the newer "rPDU2" type power bars.

I found the snmp queries to be slow against these new apcs when returning the current information, hence the increased timeout.

Any suggestions/improvements are more than welcome!

Regards

Jordan