mirror of
https://github.com/prometheus/prometheus.git
synced 2024-11-11 08:04:04 -08:00
67 lines
2.5 KiB
Markdown
67 lines
2.5 KiB
Markdown
|
---
|
||
|
|
title: Recording rules
|
||
|
|
sort_rank: 6
|
||
|
|
---
|
||
|
|
|
||
|
|
# Defining recording rules
|
||
|
|
|
||
|
|
## Configuring rules
|
||
|
|
|
||
|
|
Prometheus supports two types of rules which may be configured and then
|
||
|
|
evaluated at regular intervals: recording rules and [alerting
|
||
|
|
rules](https://prometheus.io/docs/alerting/rules/). To include rules in
|
||
|
|
Prometheus, create a file containing the necessary rule statements and have
|
||
|
|
Prometheus load the file via the `rule_files` field in the [Prometheus
|
||
|
|
configuration](../configuration.md).
|
||
|
|
|
||
|
|
The rule files can be reloaded at runtime by sending `SIGHUP` to the Prometheus
|
||
|
|
process. The changes are only applied if all rule files are well-formatted.
|
||
|
|
|
||
|
|
## Syntax-checking rules
|
||
|
|
|
||
|
|
To quickly check whether a rule file is syntactically correct without starting
|
||
|
|
a Prometheus server, install and run Prometheus's `promtool` command-line
|
||
|
|
utility tool:
|
||
|
|
|
||
|
|
```bash
|
||
|
|
go get github.com/prometheus/prometheus/cmd/promtool
|
||
|
|
promtool check-rules /path/to/example.rules
|
||
|
|
```
|
||
|
|
|
||
|
|
When the file is syntactically valid, the checker prints a textual
|
||
|
|
representation of the parsed rules to standard output and then exits with
|
||
|
|
a `0` return status.
|
||
|
|
|
||
|
|
If there are any syntax errors, it prints an error message to standard error
|
||
|
|
and exits with a `1` return status. On invalid input arguments the exit status
|
||
|
|
is `2`.
|
||
|
|
|
||
|
|
## Recording rules
|
||
|
|
|
||
|
|
Recording rules allow you to precompute frequently needed or computationally
|
||
|
|
expensive expressions and save their result as a new set of time series.
|
||
|
|
Querying the precomputed result will then often be much faster than executing
|
||
|
|
the original expression every time it is needed. This is especially useful for
|
||
|
|
dashboards, which need to query the same expression repeatedly every time they
|
||
|
|
refresh.
|
||
|
|
|
||
|
|
To add a new recording rule, add a line of the following syntax to your rule
|
||
|
|
file:
|
||
|
|
|
||
|
|
<new time series name>[{<label overrides>}] = <expression to record>
|
||
|
|
|
||
|
|
Some examples:
|
||
|
|
|
||
|
|
# Saving the per-job HTTP in-progress request count as a new set of time series:
|
||
|
|
job:http_inprogress_requests:sum = sum(http_inprogress_requests) by (job)
|
||
|
|
|
||
|
|
# Drop or rewrite labels in the result time series:
|
||
|
|
new_time_series{label_to_change="new_value",label_to_drop=""} = old_time_series
|
||
|
|
|
||
|
|
Recording rules are evaluated at the interval specified by the
|
||
|
|
`evaluation_interval` field in the Prometheus configuration. During each
|
||
|
|
evaluation cycle, the right-hand-side expression of the rule statement is
|
||
|
|
evaluated at the current instant in time and the resulting sample vector is
|
||
|
|
stored as a new set of time series with the current timestamp and a new metric
|
||
|
|
name (and perhaps an overridden set of labels).
|