给jaeger加个ENV配置呗 (#660)

Add custom environment configurations to Jeager

pkg/net/trace/jaeger/config.go

@@ -1,11 +1,33 @@
 package jaeger
 
 import (
+	"flag"
+	"os"
+
 	"github.com/go-kratos/kratos/pkg/conf/env"
 	"github.com/go-kratos/kratos/pkg/net/trace"
 )
 
+var (
+	_jaegerAppID    = env.AppID
+	_jaegerEndpoint = "http://127.0.0.1:9191"
+)
+
+func init() {
+	if v := os.Getenv("JAEGER_ENDPOINT"); v != "" {
+		_jaegerEndpoint = v
+	}
+
+	if v := os.Getenv("JAEGER_APPID"); v != "" {
+		_jaegerAppID = v
+	}
+
+	flag.StringVar(&_jaegerEndpoint, "jaeger_endpoint", _jaegerEndpoint, "jaeger report endpoint, or use JAEGER_ENDPOINT env.")
+	flag.StringVar(&_jaegerAppID, "jaeger_appid", _jaegerAppID, "jaeger report appid, or use JAEGER_APPID env.")
+}
+
+// Init Init
 func Init() {
-	c := &Config{Endpoint: "http://127.0.0.1:9191", BatchSize: 120}
+	c := &Config{Endpoint: _jaegerEndpoint, BatchSize: 120}
-	trace.SetGlobalTracer(trace.NewTracer(env.AppID, newReport(c), true))
+	trace.SetGlobalTracer(trace.NewTracer(_jaegerAppID, newReport(c), true))
 }