update doc for metrics valueKey

Author: jotak

docs/api.md

@@ -28,7 +28,7 @@ Following is the supported API format for prometheus encode:
                             absence: filter key must be absent (filter value is ignored)
                             match_regex: match filter value as a regular expression
                             not_match_regex: the filter value must not match the provided regular expression
-                 valueKey: entry key from which to resolve metric value
+                 valueKey: entry key from which to resolve metric value; leave empty to count log lines
                  labels: labels to be associated with the metric
                  remap: optional remapping of labels
                  flatten: list fields to be flattened
@@ -473,7 +473,7 @@ Following is the supported API format for writing metrics to an OpenTelemetry co
                             absence: filter key must be absent (filter value is ignored)
                             match_regex: match filter value as a regular expression
                             not_match_regex: the filter value must not match the provided regular expression
-                 valueKey: entry key from which to resolve metric value
+                 valueKey: entry key from which to resolve metric value; leave empty to count log lines
                  labels: labels to be associated with the metric
                  remap: optional remapping of labels
                  flatten: list fields to be flattened

pkg/api/encode_prom.go

@@ -51,7 +51,7 @@ type MetricsItem struct {
 	Type       MetricEncodeOperationEnum `yaml:"type" json:"type" doc:"(enum) one of the following:"`
 	Help       string                    `yaml:"help,omitempty" json:"help,omitempty" doc:"the metric help text"`
 	Filters    []MetricsFilter           `yaml:"filters" json:"filters" doc:"a list of criteria to filter entries by"`
-	ValueKey   string                    `yaml:"valueKey" json:"valueKey" doc:"entry key from which to resolve metric value"`
+	ValueKey   string                    `yaml:"valueKey" json:"valueKey" doc:"entry key from which to resolve metric value; leave empty to count log lines"`
 	Labels     []string                  `yaml:"labels" json:"labels" doc:"labels to be associated with the metric"`
 	Remap      map[string]string         `yaml:"remap" json:"remap" doc:"optional remapping of labels"`
 	Flatten    []string                  `yaml:"flatten" json:"flatten" doc:"list fields to be flattened"`