Document Loki client config (#1088)

Fixes #1071

Author: jotak

docs/api.md

@@ -318,7 +318,7 @@ Following is the supported API format for writing to loki:
          labels: map of record fields to be used as labels
          staticLabels: map of common labels to set on each flow
          ignoreList: map of record fields to be removed from the record
-         clientConfig: clientConfig
+         clientConfig: Loki client configuration, which follows the same structure as the Prometheus HTTP client config described here: https://pkg.go.dev/github.com/prometheus/common/config#HTTPClientConfig
          timestampLabel: label to use for time indexing
          timestampScale: timestamp units scale (e.g. for UNIX = 1s)
          format: the format of each line: printf (writes using golang's default map printing), fields (writes one key and value field per line) or json (default)

pkg/api/write_loki.go

@@ -37,7 +37,7 @@ type WriteLoki struct {
 	Labels         []string                     `yaml:"labels,omitempty" json:"labels,omitempty" doc:"map of record fields to be used as labels"`
 	StaticLabels   model.LabelSet               `yaml:"staticLabels,omitempty" json:"staticLabels,omitempty" doc:"map of common labels to set on each flow"`
 	IgnoreList     []string                     `yaml:"ignoreList,omitempty" json:"ignoreList,omitempty" doc:"map of record fields to be removed from the record"`
-	ClientConfig   *promConfig.HTTPClientConfig `yaml:"clientConfig,omitempty" json:"clientConfig,omitempty" doc:"clientConfig"`
+	ClientConfig   *promConfig.HTTPClientConfig `yaml:"clientConfig,omitempty" json:"clientConfig,omitempty" doc:"Loki client configuration, which follows the same structure as the Prometheus HTTP client config described here: https://pkg.go.dev/github.com/prometheus/common/config#HTTPClientConfig"`
 	TimestampLabel model.LabelName              `yaml:"timestampLabel,omitempty" json:"timestampLabel,omitempty" doc:"label to use for time indexing"`
 	// TimestampScale provides the scale in time of the units from the timestamp
 	// E.g. UNIX timescale is '1s' (one second) while other clock sources might have