How to query to know if a metric has been available for an hour

[Arnav Bose]

Hi,

I know I can check in the graph how long the metric has been available. In my case I want to create a query which will list down the data for a metric which has been available for an hour, excluding the ones which at least went down/missing during the same period. 

Here is my metric - CMSummary{ipAddr="$$$"}. There are at least 20000 different IP sources with this metric. I want to know which ones have been available for the last 1 hr. 

Thanks,

Arnav

[Julius Volz]

Do you also need to exclude IPs that are present at the beginning of the hour, go missing briefly in between (as in, the time series becomes fully absent), but are present again at the end of the hour? We don't have a way in PromQL to check whether a series has been absent just briefly within an interval, but is there most of the time. We have absent_over_time(), but that only checks whether a series has been fully absent over a given time range.

But if your IPs behave in such a way that they don't appear / disappear that rapidly, you could check which ones were there both at the beginning and the end of the interval:

  CMSummary offset 1h and CMSummary

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[Julius Volz]

Btw. you could even modify this expression to check manually every e.g. 15 minutes within the last hour, whether an IP was present at that time increment within the last hour:

    CMSummary offset 1h

  and

    CMSummary offset 45m

  and

    CMSummary offset 30m

  and

    CMSummary offset 15m

  and

    CMSummary

So you see, theoretically you could even check every minute or so for the presence, but that would become a long query...

[Aliaksandr Valialkin]

Try the following Prometheus subquery: 

count_over_time((CMSummary)[1h:1m]) == 60

It should return only time series, which were available every minute during the last hour.

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Best Regards,

Aliaksandr

[Julius Volz]

Oh yeah, smart idea for doing the same much easier, thanks :)