> ## Documentation Index
> Fetch the complete documentation index at: https://docs.flashcat.cloud/llms.txt
> Use this file to discover all available pages before exploring further.

# VictoriaLogs

> Configure alert rules for VictoriaLogs data sources

Monitors queries VictoriaLogs via HTTP, supporting querying raw logs and statistical analysis, and performing threshold evaluation and data exists/missing checks based on results.

## 1. Prerequisites

### Query Modes

<Tabs>
  <Tab title="Query Raw">
    Calls `/select/logsql/query` interface, returning two-dimensional table data.

    | Config Item     | Description                                                          |
    | --------------- | -------------------------------------------------------------------- |
    | Query Statement | e.g., `error \| fields _time, _stream, _msg \| sort by (_time) desc` |
    | Return Limit    | Limit maximum returned rows, max can be set to 100                   |
    | Time Range      | Specify query time window, e.g., "last 5 minutes"                    |
    | Label Fields    | Used to distinguish different alert entities, can configure multiple |
    | Value Fields    | Required in threshold evaluation mode                                |
  </Tab>

  <Tab title="Do Stats">
    Calls `/select/logsql/stats_query` interface, returning Prometheus protocol format data.

    | Config Item     | Description                                         |
    | --------------- | --------------------------------------------------- |
    | Query Statement | e.g., `_time:1d \| stats by (level) count(*) total` |

    <Warning>
      Query statement must include `_time` filter condition (like `_time:5m`), otherwise it will query all data causing performance issues.
    </Warning>
  </Tab>
</Tabs>

<Tip>
  VictoriaLogs data source most recommends using "Data Exists Mode", best suited for log scenarios.
</Tip>

## 2. Threshold Evaluation Mode

Both **Query Raw** and **Do Stats** query modes can be used. Examples below explain each.

### 2.1 Query Raw Example

Query statement example:

```
level:ERROR | stats by (level) count(*) total
```

Result looks like:

| level | total |
| ----- | ----- |
| ERROR | 150   |

Configure value field as `total`, label field as `level` (or leave empty, Monitors will auto-detect). Different threshold different level configuration examples:

* Warning: `$A.total >= 50` or shorthand `$A >= 50` (since there's only one value field: total)
* Critical: `$A.total >= 100` or shorthand `$A >= 100` (since there's only one value field: total)

### 2.2 Do Stats Example

Query statement example:

`_time:1d and level:ERROR | stats by (level) count(*) total`

Result follows Prometheus protocol format:

```
total{level="ERROR"} 150
```

Different threshold different level configuration examples:

* Warning: `$A.total >= 50` or shorthand `$A >= 50` (since there's only one metric field: total)
* Critical: `$A.total >= 100` or shorthand `$A >= 100` (since there's only one metric field: total)

### 2.3 Recovery Logic

| Strategy                        | Description                                                                               |
| ------------------------------- | ----------------------------------------------------------------------------------------- |
| **Auto Recovery**               | When values no longer satisfy any alert threshold, automatically generates recovery event |
| **Specific Recovery Condition** | Configure recovery expression (e.g., `$A.total < 10`) to reduce flapping                  |
| **Recovery Query**              | Independent query for recovery evaluation, supports `${label_name}` variables             |

## 3. Data Exists Mode

<Note>
  This is the **most recommended VictoriaLogs alert configuration method**, because log scenarios are better suited for "alert when anomalous data exists" mode.
</Note>

This mode writes all filter logic in VictoriaLogs query; Monitors only determines "whether data is returned".

**Query statement example (Do Stats mode):**

```
_time:15m and level:ERROR | stats by (level) count(*) total | filter total:>10
```

Where `| filter total:>10` filters data with `total` greater than 10. As long as data rows satisfying this condition are returned, Monitors triggers alert; if no data rows satisfy this condition, alert is considered recovered.

## 4. No Data Mode

No Data mode is used to monitor "logs that should be continuously generated are no longer appearing", common scenarios:

* Application instance no longer producing logs (possibly process exited)
* Log collection pipeline anomaly (like agent down or output blocked)

### Configuration Example

Query statement (**Do Stats** mode):

```
_time:15m and level:INFO | stats by (level) count(*) total
```

Scenario: A service should always have INFO log output; if no INFO logs are generated in the last 15 minutes, trigger alert.

## 5. Getting Original Logs During Alert

Alert query conditions typically use "Do Stats" mode, which doesn't return original logs. Monitors supports configuring "Related Query" in alert rules to additionally query original logs when alert triggers.

![](https://docs-cdn.flashcat.cloud/imges/mon/b5c1890d90cecf967695a4b0a4b4fba0.png)

"Related Query" results can be rendered in "Notes Description", example:

```
{{- if eq $status "firing" }}
triggered value: {{ $value | printf "%.3f" }}
{{- range $x := $relates.R1}}
{{- range $k, $v := $x.Fields }}
{{- if eq $k "_time" }}
{{ $k }} : {{ timeFormat $v "2006-01-02T15:04:05Z07:00" 8 }}
{{- else }}
{{ $k }} : {{ $v }}
{{- end }}
{{- end }}
{{- end}}
{{- else}}
Recovered
{{- end}}
```