Adopt the new design of the plugin

observability/config.go

@@ -29,15 +29,15 @@ import (
 )
 
 const (
-	envKeyObservabilityConfig = "GRPC_CONFIG_OBSERVABILITY"
-	envProjectID              = "GOOGLE_CLOUD_PROJECT"
+	envObservabilityConfig = "GRPC_CONFIG_OBSERVABILITY"
+	envProjectID           = "GOOGLE_CLOUD_PROJECT"
 )
 
 // fetchDefaultProjectID fetches the default GCP project id from environment.
 func fetchDefaultProjectID(ctx context.Context) string {
 	// Step 1: Check ENV var
 	if s := os.Getenv(envProjectID); s != "" {
-		logger.Infof("Found project ID from env GOOGLE_CLOUD_PROJECT: %v", s)
+		logger.Infof("Found project ID from env %v: %v", envProjectID, s)
 		return s
 	}
 	// Step 2: Check default credential
@@ -56,10 +56,10 @@ func fetchDefaultProjectID(ctx context.Context) string {
 
 func parseObservabilityConfig() *configpb.ObservabilityConfig {
 	// Parse the config from ENV var
-	if content := os.Getenv(envKeyObservabilityConfig); content != "" {
+	if content := os.Getenv(envObservabilityConfig); content != "" {
 		var config configpb.ObservabilityConfig
 		if err := protojson.Unmarshal([]byte(content), &config); err != nil {
-			logger.Warningf("Error parsing observability config from env GRPC_CONFIG_OBSERVABILITY: %v", err)
+			logger.Warningf("Error parsing observability config from env %v: %v", envObservabilityConfig, err)
 			return nil
 		}
 		logger.Infof("Parsed ObservabilityConfig: %+v", &config)

observability/exporting.go

@@ -28,10 +28,9 @@ import (
 	"google.golang.org/protobuf/encoding/protojson"
 )
 
-// loggingExporter is the interface of logging exporter for gRPC
-// Observability. Ideally, we should use what OTEL provides, but their Golang
-// implementation is in "frozen" state. So, this plugin provides a minimum
-// interface to satisfy testing purposes.
+// loggingExporter is the interface of logging exporter for gRPC Observability.
+// In future, we might expose this to allow users provide custom exporters. But
+// now, it exists for testing purposes.
 type loggingExporter interface {
 	// EmitGrpcLogRecord writes a gRPC LogRecord to cache without blocking.
 	EmitGrpcLogRecord(*grpclogrecordpb.GrpcLogRecord)
@@ -114,11 +113,13 @@ func (cle *cloudLoggingExporter) Close() error {
 		if err := cle.logger.Flush(); err != nil {
 			return err
 		}
+		cle.logger = nil
 	}
 	if cle.client != nil {
 		if err := cle.client.Close(); err != nil {
 			return err
 		}
+		cle.client = nil
 	}
 	logger.Infof("Closed CloudLogging exporter")
 	return nil