add tag name

pkg/exporters/gelf_exporter/config.go

@@ -3,6 +3,7 @@ package gelfexporter
 type config struct {
 	GelfUrl string
 	AppName string
+	Tag     string
 }
 
 // newConfig creates a validated Config configured with options.
@@ -40,3 +41,14 @@ func (o appName) apply(cfg config) config {
 	cfg.AppName = string(o)
 	return cfg
 }
+
+func WithTag(tagStr string) Option {
+	return tag(tagStr)
+}
+
+type tag string
+
+func (o tag) apply(cfg config) config {
+	cfg.Tag = string(o)
+	return cfg
+}

pkg/exporters/gelf_exporter/gelf.go

@@ -23,6 +23,8 @@ type GELFMessage struct {
 
 	// All additional field names must start with an underline.
 	ExtraFields map[string]interface{} `json:"extrafields,omitempty"`
+
+	Tag string `json:"tag,omitempty"`
 }
 
 func Log(writer *gelf.UDPWriter, msg GELFMessage) {
@@ -38,6 +40,7 @@ func Log(writer *gelf.UDPWriter, msg GELFMessage) {
 
 func (g GELFMessage) GELFFormat() *gelf.Message {
 	prefixedExtras := make(map[string]interface{}, len(g.ExtraFields))
+	prefixedExtras["tag"] = g.Tag
 	for k, v := range g.ExtraFields {
 		prefixedExtras["_"+k] = v
 	}

pkg/exporters/gelf_exporter/trace.go

@@ -30,6 +30,7 @@ func New(options ...Option) (*Exporter, error) {
 	return &Exporter{
 		gelfWriter: writer,
 		appName:    cfg.AppName,
+		tag:        cfg.Tag,
 	}, nil
 
 }
@@ -37,6 +38,7 @@ func New(options ...Option) (*Exporter, error) {
 type Exporter struct {
 	gelfWriter *gelf.UDPWriter
 	appName    string
+	tag        string
 	stoppedMu  sync.RWMutex
 	stopped    bool
 }