proposal for combining labels

[Dhiman Barman]

Hi,

It will be useful to have a way to combine metric labels and create a new label as follows. 

metric_name{label1=a, label2=b}  => metric_name{label1=a, label2=b, combined_label=a_b}

metric_name{label1=b, label2=a}  => metric_name{label1=b, label2=a, combined_label=a_b}

The combined label will be inserted into the original metric. In the AlertManager, we can use group_by{} on the 

combined label so two separate tickets do not get created in JIRA. Furthermore, we also do not want

AlertManager to propagate the combined_label downstream. The combined label is for grouping in the 

AlertManager only. 

Will there be any issue if this feature is added in Prometheus ? 

Thanks,

Dhiman

[Julien Pivotto]

On 12 Feb 11:57, Dhiman Barman wrote:
> Hi,
>
> It will be useful to have a way to combine metric labels and create a new
> label as follows.
>
> metric_name{label1=a, label2=b} => metric_name{label1=a, label2=b,
> combined_label=a_b}
> metric_name{label1=b, label2=a} => metric_name{label1=b, label2=a,
> combined_label=a_b}

You can use label_join
https://prometheus.io/docs/prometheus/latest/querying/functions/#label_join

Or do that with metrics relabelling.

> The combined label will be inserted into the original metric. In the

> AlertManager, we can use *group_by{}* on the

> combined label so two separate tickets do not get created in JIRA.
> Furthermore, we also do not want
> AlertManager to propagate the combined_label downstream. The combined label
> is for grouping in the
> AlertManager only.

You don't need to combine to group them together.

>
> Will there be any issue if this feature is added in Prometheus ?
>
> Thanks,
> Dhiman
>

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[Dhiman Barman]

HI,

If we use group_by() on the two labels - label1 and label2, how will it work because value pairs are (a, b) and (b, a) ? Will it not create separate alarms/notifications ? I need the value for the combined label to be "a_b" so the values need to be sorted. 

However, label_join() can be enhanced and another operator label_join_sorted() can be supported which will sort the values before creating a new metric. 

Thanks,

Dhiman

[Julien Pivotto]

Hi,


Label values are opaque to Prometheus. It looks like you would better fix your input labels.

Regards,

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