mirror of
https://github.com/prometheus/prometheus.git
synced 2026-05-17 02:26:56 +02:00
4a5aef0495
* Cut v2.28.0-rc.0 (#8954) * Cut v2.28.0-rc.0 Signed-off-by: Julius Volz <julius.volz@gmail.com> * Changelog fixup Signed-off-by: Julius Volz <julius.volz@gmail.com> * Address review comments Signed-off-by: Julius Volz <julius.volz@gmail.com> * Downgrade some features to enhancements Signed-off-by: Julius Volz <julius.volz@gmail.com> * Adjust release date to today Signed-off-by: Julius Volz <julius.volz@gmail.com> * Migrate HTTP SD docs from docs repo (#8972) See discussion in https://github.com/prometheus/docs/pull/1975 Signed-off-by: Julius Volz <julius.volz@gmail.com> * Cut Prometheus v2.28.0 (#8973) Signed-off-by: Julius Volz <julius.volz@gmail.com>
56 lines
2.7 KiB
Markdown
56 lines
2.7 KiB
Markdown
---
|
||
title: Disabled Features
|
||
sort_rank: 11
|
||
---
|
||
|
||
# Disabled Features
|
||
|
||
Here is a list of features that are disabled by default since they are breaking changes or are considered experimental.
|
||
Their behaviour can change in future releases which will be communicated via the [release changelog](https://github.com/prometheus/prometheus/blob/main/CHANGELOG.md).
|
||
|
||
You can enable them using the `--enable-feature` flag with a comma separated list of features.
|
||
They may be enabled by default in future versions.
|
||
|
||
## `@` Modifier in PromQL
|
||
|
||
`--enable-feature=promql-at-modifier`
|
||
|
||
The `@` modifier lets you specify the evaluation time for instant vector selectors,
|
||
range vector selectors, and subqueries. More details can be found [here](querying/basics.md#modifier).
|
||
|
||
## Expand environment variables in external labels
|
||
|
||
`--enable-feature=expand-external-labels`
|
||
|
||
Replace `${var}` or `$var` in the [`external_labels`](configuration/configuration.md#configuration-file)
|
||
values according to the values of the current environment variables. References
|
||
to undefined variables are replaced by the empty string.
|
||
|
||
## Negative offset in PromQL
|
||
|
||
This negative offset is disabled by default since it breaks the invariant
|
||
that PromQL does not look ahead of the evaluation time for samples.
|
||
|
||
`--enable-feature=promql-negative-offset`
|
||
|
||
In contrast to the positive offset modifier, the negative offset modifier lets
|
||
one shift a vector selector into the future. An example in which one may want
|
||
to use a negative offset is reviewing past data and making temporal comparisons
|
||
with more recent data.
|
||
|
||
More details can be found [here](querying/basics.md#offset-modifier).
|
||
|
||
## Remote Write Receiver
|
||
|
||
`--enable-feature=remote-write-receiver`
|
||
|
||
The remote write receiver allows Prometheus to accept remote write requests from other Prometheus servers. More details can be found [here](storage.md#overview).
|
||
|
||
## Exemplars Storage
|
||
|
||
`--enable-feature=exemplar-storage`
|
||
|
||
[OpenMetrics](https://github.com/OpenObservability/OpenMetrics/blob/main/specification/OpenMetrics.md#exemplars) introduces the ability for scrape targets to add exemplars to certain metrics. Exemplars are references to data outside of the MetricSet. A common use case are IDs of program traces.
|
||
|
||
Exemplar storage is implemented as a fixed size circular buffer that stores exemplars in memory for all series. Enabling this feature will enable the storage of exemplars scraped by Prometheus. The flag `storage.exemplars.exemplars-limit` can be used to control the size of circular buffer by # of exemplars. An exemplar with just a `traceID=<jaeger-trace-id>` uses roughly 100 bytes of memory via the in-memory exemplar storage. If the exemplar storage is enabled, we will also append the exemplars to WAL for local persistence (for WAL duration).
|