Please add a .set() method to counters in java client

[Patrick Hemmer]

This is a feature request to add a `.set()` method to counters on the java client.

Currently java counters only have a `.inc()` method. This is not practical to work with when your input is an absolute value instead of a relative one, and on top of that, when the value can reset to 0 (which prometheus counters do allow).

Thanks

[Julius Volz]

Hi,

When your input is an absolute value, and one that can reset on you outside of your control, it sounds like you are translating existing third-party state into a Prometheus metric (rather than being the one in charge of counting things as they happen). So you are not looking to track state, but just to expose it. For that use case, you would use a custom collector and export a constant, throw-away metric for every scrape: https://github.com/prometheus/client_java#custom-collectors

See also https://prometheus.io/docs/instrumenting/writing_exporters/#collectors

Basically, direct instrumentation (with just .add() and no .set()) is for when you are the one tracking metrics, not just proxying existing state.

Cheers,

Julius

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Julius Volz

PromLabs - promlabs.com

[Julien Pivotto]

On 16 May 22:41, Julius Volz wrote:
> Hi,
>
> When your input is an absolute value, and one that can reset on you outside
> of your control, it sounds like you are translating existing third-party
> state into a Prometheus metric (rather than being the one in charge of
> counting things as they happen). So you are not looking to track state, but
> just to expose it. For that use case, you would use a custom collector and
> export a constant, throw-away metric for every scrape:
> https://github.com/prometheus/client_java#custom-collectors
>
> See also
> https://prometheus.io/docs/instrumenting/writing_exporters/#collectors
>
> Basically, direct instrumentation (with just .add() and no .set()) is for
> when you are the one tracking metrics, not just proxying existing state.

I would also add that a counter can not be set to 0 in Prometheus, nor
downgraded.

In such cases, you will need a Gauge.

https://prometheus.io/docs/concepts/metric_types/


regards,

>
> Cheers,
> Julius
>
> On Sat, May 16, 2020 at 9:19 PM Patrick Hemmer <patrick...@gmail.com>
> wrote:
>
> > This is a feature request to add a `.set()` method to counters on the java
> > client.
> >
> > Currently java counters only have a `.inc()` method. This is not practical
> > to work with when your input is an absolute value instead of a relative
> > one, and on top of that, when the value can reset to 0 (which prometheus
> > counters do allow).
> >
> > Thanks
> >
> > --
> > You received this message because you are subscribed to the Google Groups
> > "Prometheus Users" group.
> > To unsubscribe from this group and stop receiving emails from it, send an
> > email to prometheus-use...@googlegroups.com.
> > To view this discussion on the web visit
> > https://groups.google.com/d/msgid/prometheus-users/be9e8a91-45c5-49fc-96b9-c054fb33d74c%40googlegroups.com

> > <https://groups.google.com/d/msgid/prometheus-users/be9e8a91-45c5-49fc-96b9-c054fb33d74c%40googlegroups.com?utm_medium=email&utm_source=footer>
> > .

> >
>
>
> --
> Julius Volz
> PromLabs - promlabs.com
>

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Julien Pivotto
@roidelapluie