Export counters as counters

[jkohen]

I work on the Stackdriver integration with Prometheus and a user filed an issue because this redis exporter exports counters as gauges, and Stackdriver doesn't allow rate computations over gauge. I know this isn't a major problem for Prometheus (it can mostly cause glitches on process restart), but would you consider fixing the setMetrics method to set the right metric type? Any workaround on our side will be hard to maintain. Thanks!

[oliver006]

Thanks for raising the issue.
From looking at the Prometheus Golang library docs here (and #31 ) it looks like using a ConstMetric is way to go.
Alas, I currently don't have bandwidth to implement that change and it's not a priority for me as I don't use Stackdriver but I'd be happy to review & merge a PR if you (or anyone else ) submits one.

[oliver006]

Actually, it might be a lot more easy change than I initially thought.

Replacing this part:

redis_exporter/exporter/redis.go

Lines 905 to 916 in 8d260bf

	e.metrics[name] = prometheus.NewGaugeVec(prometheus.GaugeOpts{
	Namespace: e.namespace,
	Name: name,
	Help: name + "metric", // needs to be set for prometheus >= 2.3.1
	}, []string{"addr", "alias"})
	e.metricsMtx.Unlock()
	}
	var labels prometheus.Labels = map[string]string{"addr": scr.Addr, "alias": scr.Alias}
	if len(scr.DB) > 0 {
	labels["db"] = scr.DB
	}
	e.metrics[name].With(labels).Set(float64(scr.Value))

with something that uses NewCounterFunc might do the trick.

[lukmdo]

@jkohen IMO Gauges are more appropriate for common case (redis values can go up and down)
which value would you like to calculate rate on ?

only ones that get pass making are included

redis_exporter/exporter/redis.go

Lines 335 to 341 in 56bddc2

	func includeMetric(s string) bool {
	if strings.HasPrefix(s, "db") || strings.HasPrefix(s, "cmdstat_") || strings.HasPrefix(s, "cluster_") {
	return true
	}
	_, ok := metricMap[s]
	return ok
	}

@oliver006 perhaps
a) ones from metricMap that are*_total could use ConstMetric of type CounterValue ?
b) or better by adding types to metricMap

[oliver006]

a) could be a quick hack to make it work but I was thinking about going with option b) and store what type metric to use with each entry in the map.

[jkohen]

Thank you, Oliver!

@mtanda FYI, this has been closed. In reference to Stackdriver/stackdriver-prometheus#14 you filed.

[mtanda]

@jkohen That's fantastic!
Thank you for notifying me.

Dear Oliver,
Thank you for your work. I appreciate so much!