How to use the processor_appender plugin to append a specific value to a specified field-Simple Log Service(SLS)-阿里云帮助中心

The processor_appender plugin appends a specific value to an existing or new field and supports template variables in the field value. This plugin is commonly used with time series monitoring plugins such as input_prometheus and input_system_v2 to enrich data pulled from Prometheus.

Important

Logtail 0.16.66 and later supports the processor_appender plugin.

Parameters

Set type to processor_appender. The following table describes the parameters in the detail field.

Table 1. Plugin parameters

Parameter	Type	Required	Description
Key	string	Yes	The field name.
Value	string	Yes	The value to append. Template variables are supported. For more information, see Template variables.
SortLabels	boolean	No	Specifies whether to sort labels alphabetically when Key is set to __labels__. Set this parameter to true to prevent query errors caused by unsorted labels. Default value: false.

Table 2. Template variables

Template variable	Description	Configuration example	Result example
{{__ip__}}	The IP address of the server where Logtail is installed.	"Value": "{{__ip__}}"	"Value": "192.0.2.1"
{{__host__}}	The hostname of the server where Logtail is installed.	"Value": "{{__host__}}"	"Value": "logtail-ds-xdfaf"
{{$xxxx}}	The value of the specified environment variable. The variable name must start with a dollar sign ($).	"Value": "{{$WORKING_GROUP}}"	"Value": "prod"

Example

Assume a Logtail server has the IP address 192.0.2.1, the hostname david, and the environment variable WORKING_GROUP set to prod. The following configuration appends this data to the __labels__ field:

Raw data
```
"__labels__":"a#$#b"
```

Logtail plugin configuration

{
  "processors":[
    {
      "type":"processor_appender",
      "detail": {
        "Key": "__labels__",
        "Value": "|host#$#{{__host__}}|ip#$#{{__ip__}}|group#$#{{$WORKING_GROUP}}",
        "SortLabels": true
      }
    }
  ]
}

Result

"__labels__":"a#$#b|group#$#prod|host#$#david|ip#$#192.0.2.1"