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Merge pull request #179 from vgropp/patch-1

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fixes #178 doc for raw_expressions
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Christoph Petrausch
2025-11-16 11:51:40 +01:00
committed by GitHub
parent 93a77607f6 656f219bc6
commit cc82a38b21
1 changed files with 9 additions and 1 deletions
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@@ -375,7 +375,7 @@ During the evaluation, the following variables are available to the expression:
* `last_result` - the result from the previous expression evaluation (a float for `raw_expression`/`expression`, a string for `dynamic_labels`) * `last_result` - the result from the previous expression evaluation (a float for `raw_expression`/`expression`, a string for `dynamic_labels`)
* `elapsed` - the time that passed since the previous evaluation, as a [Duration](https://pkg.go.dev/time#Duration) value * `elapsed` - the time that passed since the previous evaluation, as a [Duration](https://pkg.go.dev/time#Duration) value
The [language definition](https://expr-lang.org/docs/v1.9/Language-Definition) describes the expression syntax. In addition, the following functions are available: The [language definition](https://expr-lang.org/docs/language-definition) describes the expression syntax. In addition, the following functions are available:
* `now()` - the current time as a [Time](https://pkg.go.dev/time#Time) value * `now()` - the current time as a [Time](https://pkg.go.dev/time#Time) value
* `int(x)` - convert `x` to an integer value * `int(x)` - convert `x` to an integer value
* `float(x)` - convert `x` to a floating point value * `float(x)` - convert `x` to a floating point value
@@ -400,6 +400,14 @@ If `raw_expression` is set, the generated value of the expression is exported to
1. If `force_monotonicy` is set to `true`, any new value that is smaller than the previous one is considered to be a counter reset. When a reset is detected, the previous value becomes the value offset which is automatically added to each consecutive value. The offset is persistet between restarts of mqtt2prometheus. 1. If `force_monotonicy` is set to `true`, any new value that is smaller than the previous one is considered to be a counter reset. When a reset is detected, the previous value becomes the value offset which is automatically added to each consecutive value. The offset is persistet between restarts of mqtt2prometheus.
1. If `mqtt_value_scale` is set to a non-zero value, it is applied to the the value to yield the final metric value. 1. If `mqtt_value_scale` is set to a non-zero value, it is applied to the the value to yield the final metric value.
#### Expressions in docker environment
With expressions enabled the exporter will persist the conversion into /var/lib/mqtt2prometheus. This directory needs to be writable for the user. One solution is to use `--tmpfs /var/lib/mqtt2prometheus:uid=65532,gid=65532,mode=700` in your docker command or to add to docker-compose.yml
```
tmpfs:
- /var/lib/mqtt2prometheus:uid=65532,gid=65532,mode=0700
```
## Frequently Asked Questions ## Frequently Asked Questions
### Listen to multiple Topic Pathes ### Listen to multiple Topic Pathes