Also, the whole expression can be simplified to:
(node_memory_MemTotal_bytes{job="kubernetes-service-endpoints",cluster="$cluster",instance=~"$node"}
- node_memory_MemFree_bytes) * on(instance)
group_left(nodename) node_uname_info
This is because you don't need to filter both node_memory_MemTotal_bytes
and node_memory_MemFree_bytes. When you combine them with a binary
operator (in this case subtraction), the result vector will only have
values where both LHS and RHS have exactly matching labels. So any values
from the RHS which don't match the LHS are discarded automatically, without
having to explicitly filter them..
On Tuesday, 13 December 2022 at 09:03:36 UTC Brian Candler wrote:
> If you want to do this inside prometheus, then you want recording rules
> <https://prometheus.io/docs/prometheus/latest/configuration/recording_rules/>
> .
>
> Note that with recording rules you're not really creating a new
> "variable", you're creating a whole new timeseries. However this is what
> you need, since your second query wants to perform aggregation_over_time()
> on these precomputed values.
>
> It'll take a week until you have enough data from your recording rule to
> use, unless you backfill
> <https://prometheus.io/docs/prometheus/latest/storage/#backfilling-for-recording-rules>
> .
>
> Your other option is to substitute the first expression into the two
> places where you want to use it in the second expression. But in this
> case, you'll need to use a subquery
> <https://prometheus.io/docs/prometheus/latest/querying/basics/#subquery>,
> e.g.
>
> (some - long - expression)[1w:1h]
>
> rather than
>
> metric[1w]
>
> The subquery shown evaluates (some - long - expression) over a 1w period
> at 1h intervals to create a range vector. Note that unlike a simple metric
> range vector, you need to give it the sampling interval. Or you can write
>
> (some - long - expression[1w:]
>
> but this will just use whatever global default evaluation interval you
> have configured (which might be, say, 15 seconds or 1 minute)
>
> P.S. Are you sure that query you showed is valid? The first part is fine,
> but the end doesn't make sense to me, and I can't see this syntax permitted
> either by operators
> <https://prometheus.io/docs/prometheus/latest/querying/operators/#group-modifiers>
>
> or functions
> <https://prometheus.io/docs/prometheus/latest/querying/functions/>.
>
>
> node_memory_MemTotal_bytes{job="kubernetes-service-endpoints",cluster="$cluster",instance=~"$node"}
>
> * on(instance) group_left(nodename)
> *group(node_uname_info{})by(instance,nodename)*
>
> I would write this as simply:
>
>
> node_memory_MemTotal_bytes{job="kubernetes-service-endpoints",cluster="$cluster",instance=~"$node"}
>
> * on(instance) group_left(nodename) node_uname_info
>
> assuming that:
> - N instances of the LHS match to 1 instance of the RHS with a
> corresponding "instance" label
> - you want to add the "nodename" label from the RHS to all the timeseries
> returned by the LHS
>
> On Tuesday, 13 December 2022 at 08:03:32 UTC [email protected] wrote:
>
>> Hello All,
>>
>> I wanted to store the below Prometheus query into an variable.
>> (node_memory_MemTotal_bytes{job="kubernetes-service-endpoints",cluster="$cluster",instance=~"$node"}
>>
>> * on(instance) group_left(nodename)
>> group(node_uname_info{})by(instance,nodename)-(node_memory_MemFree_bytes{job="kubernetes-service-endpoints",cluster="$cluster",instance=~"$node"}
>>
>> * on(instance) group_left(nodename)
>> group(node_uname_info{})by(instance,nodename) ))
>>
>> and use it in second query ,
>> z = (sum(rate(metric)[1m]) - sum(avg_over_time(metric[1w])) /
>> sum(stddev_over_time(metric[1w]))
>>
>> Is there any way to achieve this.
>> Thankyou
>>
>>
>>
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