mirror of https://github.com/prometheus/prometheus
49 lines
1.8 KiB
Markdown
49 lines
1.8 KiB
Markdown
---
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title: Disabled Features
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sort_rank: 10
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---
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# Disabled Features
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Here is a list of features that are disabled by default since they are breaking changes or are considered experimental.
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Their behaviour can change in future releases which will be communicated via the [release changelog](https://github.com/prometheus/prometheus/blob/main/CHANGELOG.md).
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You can enable them using the `--enable-feature` flag with a comma separated list of features.
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They may be enabled by default in future versions.
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## `@` Modifier in PromQL
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`--enable-feature=promql-at-modifier`
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The `@` modifier lets you specify the evaluation time for instant vector selectors,
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range vector selectors, and subqueries. More details can be found [here](querying/basics.md#modifier).
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## Expand environment variables in external labels
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`--enable-feature=expand-external-labels`
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Replace `${var}` or `$var` in the [`external_labels`](configuration/configuration.md#configuration-file)
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values according to the values of the current environment variables. References
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to undefined variables are replaced by the empty string.
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## Negative offset in PromQL
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This negative offset is disabled by default since it breaks the invariant
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that PromQL does not look ahead of the evaluation time for samples.
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`--enable-feature=promql-negative-offset`
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In contrast to the positive offset modifier, the negative offset modifier lets
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one shift a vector selector into the future. An example in which one may want
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to use a negative offset is reviewing past data and making temporal comparisons
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with more recent data.
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More details can be found [here](querying/basics.md#offset-modifier).
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## Remote Write Receiver
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`--enable-feature=remote-write-receiver`
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The remote write receiver allows Prometheus to accept remote write requests from other Prometheus servers. More details can be found [here](storage.md#overview).
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