Hi Brian, and thank you very much for your detailed answer... which I have
read very carefully several times.
Maybe I forgot a detail in my question, that is: I'm using Grafana!
Your concepts also related to the muting of the reports are clear to me and
absolutely correct. These are not related to the alerts in grafana,
unfortunately, but to the communication points where the recipients of the
messages are defined.
So to simplify, it would be... in this particular case easier to fix it
directly in the prom-QL code.
I would simply like to know how I can also include the 30 minutes only from
8:00 AM so that it becomes 8:30 AM... I don't know if exists the right
syntax in prom-QL
Thanks again and have a nice day.
ALEN
Il giorno sabato 25 giugno 2022 alle 11:21:51 UTC+2 Brian Candler ha
scritto:
> Firstly, given that you have put "or vector(0)", I think you may
> misunderstand how alerting works in Prometheus.
>
> PromQL expressions return vectors - a set of 0 or more values. In an
> alerting expression, the alert is treated as firing if the vector is
> non-empty - i.e. it contains 1 or more values, regardless of what those
> values actually are. Therefore, the expression vector(0) gives an alert
> which fires all of the time, which isn't very useful.
>
> Next, PromQL comparison operators are filters, not booleans. Suppose you
> have the following metrics in your database:
>
> node_disk_space{instance="a"} 100
> node_disk_space{instance="b"} 200
> node_disk_space{instance="c"} 300
>
> The PromQL expression "node_disk_space > 150" returns a vector of 2 values:
>
> node_disk_space{instance="b"} 200
> node_disk_space{instance="c"} 300
>
> That is, the expression "node_disk_space" returns a vector of all metrics
> with that metric name, and "node_disk_space > 150" filters it down to just
> those metrics whose value is over 150. It does not return a "true" or
> "false" value (or values).
>
> Similarly, "and/or/unless" don't work like booleans either. The
> expression "node_disk_space > 150 or vector(0)" will return the following:
>
> node_disk_space{instance="b"} 200
> node_disk_space{instance="c"} 300
> {} 0
>
> In this case you get a vector of 3 values. The explanation of how "or"
> works is here:
>
> https://prometheus.io/docs/prometheus/latest/querying/operators/#logical-set-binary-operators
> It's another vector operator, which matches the label sets of the LHS and
> RHS.
>
> Now, let me go back to your original problem about time periods. I think
> you're approach this the wrong way.
>
> I believe the business rule amounts to this: "I only want to receive
> alerts on this condition if the time falls between 8:30am and 9pm". It's
> not that the problem doesn't happen outside business hours; it's that the
> problem isn't important enough to send a notification outside of business
> hours.
>
> Therefore, the right way to handle this is with time periods within
> alertmanager, to control when the alerts are sent - not within the PromQL
> expression which determines whether there is a problem or not.
>
> The way you do this is with time intervals in alertmanager routing trees.
> See:
> https://prometheus.io/docs/alerting/latest/configuration/#route
> https://prometheus.io/docs/alerting/latest/configuration/#time_interval
>
> Not only is this far easier to implement than attempting to do it in
> PromQL, it's also more flexible - for example you can have the same alert
> (from the same PromQL alerting rule) sent to different groups depending on
> the time of day.
>
> Note that you can add labels to your alert in the alerting rule to
> categorise the alert, and you can match on those labels in your alert
> routing tree. This gives you further flexibility to categorise your alerts
> in whatever way is useful to you.
>
> On Friday, 24 June 2022 at 23:20:42 UTC+1 [email protected] wrote:
>
>> Hi,
>> I'm try to write this simple code for Prometheus
>> but I don't understand how can I include also minutes... with a valide
>> range of hour.
>>
>> Alert could firing only between: *08:30 AM to all 09:00 P.M*.
>>
>> Here below the hours are in CET (+2 from Italy where I'm)
>>
>> (count by (exported_instance, counter_instance)
>> (database_status{job="aaaa", exported_instance="myserver",
>> status!="ONLINE"})
>> and on() hour() >= 6 <= 19
>> *......... miss minute .......*
>> ) or vector(0)
>>
>> Thanks Alen
>>
>
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