Customizing labels with SNMP Exporter

[Elliott Balsley]

I have an SNMP device which returns a table of sensors, including columns for left fan and right fan speed.  After applying a lookup in the generator, the metrics look like this:

unit_fan_left{ledStatusUnitPortId="1",ledStatusUnitUnitId="1"} 1450

unit_fan_right{ledStatusUnitPortId="1",ledStatusUnitUnitId="1"} 1449

Is it possible to combine these into one metric with a fan label like this?

unit_fan{ledStatusUnitPortId="1",ledStatusUnitUnitId="1", fan="left"} 1450

unit_fan{ledStatusUnitPortId="1",ledStatusUnitUnitId="1", fan="right"} 1449

[Elliott Balsley]

I was hoping to do this in the exporter, but otherwise I can do it easily enough with a relabel config on the scrape.