Thanks for suggestions.
The difference is that in case of missed scrape , I want the rule to
produce to produce "nothing" for the missed instance. So having a gap in
the graph. I could use 'irate()[10m] * 300' as you suggest, but I don't see
the difference with increase(). Also I'm not using the default
lookback-delta but increased delta 9m.
Any idea why the range query with the same datasource in grafana works, but
the rule fails to create metrics for some instances?
Marek
On Friday, July 23, 2021 at 11:09:20 AM UTC+2 Julien Pivotto wrote:
> On 23 Jul 01:04, Marek Skalicky wrote:
> > Hi,
> > I'm running prometheus with lookback-delta=9m and scraping a metric
> every 5
> > minutes. I've seen issue when evaluating
> > 'increase(ifHCInOctets{network_key="xxx"}[10m])/2' in recording rule.
> > I've reported that as a bug in
> > https://github.com/prometheus/prometheus/issues/9092, but I was told
> the
> > lookback-delta should be 15m so it's an issue of configuration.
> >
> > But when I do the same query in grafana it shows correctly. So does the
> > lookback-delta have special meaning for recording rules?
> > My understanding was that the lookback delta is used per individual data
> > points, so the fact that the query/rule has range vector 10m has nothing
> to
> > do with the lookback delta. I have also recording rules doing "the same"
> > with 1h and 24h range vector and those work fine.
> >
> > Could anyone please explain why I should use 15m lookback-delta?
>
> In your case you have a very low scrape interval, 300s. That means that
> for your prometheus server, if you query data, you would find some
> oddities with the default lookback delta.
>
> When I did look at the issue, I did not notice that you were using
> increase. Then, loopback delta does not play a role. Instead, you should
> use:
>
> irate(ifHCInOctets{network_key="xxx"}[15m])
>
> which seems a better option.
>
> 15 min should ensure there is at least 2 datapoints, and irate will do
> the calculation between the last 2 datapoints.
>
> >
> > Many thanks,
> > Marek Skalicky
> >
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>
>
> --
> Julien Pivotto
> @roidelapluie
>
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