fix: retain existing variables and mark them deprecated

Author: Yushu.Kozaki

constant.go

@@ -3,8 +3,14 @@ package gcpen
 const (
 	EnvKeyProjectID          = "GCP_PROJECT"          // for Google Cloud Functions
 	EnvKeyGoogleCloudProject = "GOOGLE_CLOUD_PROJECT" // for Google App Engine
-	EnvKeyGAEServiceName     = "GAE_SERVICE"          // for Google App Engine
-	EnvKeyGAEServiceVersion  = "GAE_VERSION"          // for Google App Engine
-	EnvKeyRUNServiceName     = "K_SERVICE"            // for Google Cloud Run
-	EnvKeyRUNServiceRevision = "K_REVISION"           // for Google Cloud Run
+
+	// Deprecated
+	EnvKeyServiceName = "GAE_SERVICE" // for Google App Engine
+	// Deprecated
+	EnvKeyServiceVersion = "GAE_VERSION" // for Google App Engine
+
+	EnvKeyGAEServiceName     = "GAE_SERVICE" // for Google App Engine
+	EnvKeyGAEServiceVersion  = "GAE_VERSION" // for Google App Engine
+	EnvKeyRUNServiceName     = "K_SERVICE"   // for Google Cloud Run
+	EnvKeyRUNServiceRevision = "K_REVISION"  // for Google Cloud Run
 )

environ.go

@@ -7,6 +7,15 @@ import (
 var (
 	// ProjectID - Google Cloud Platform Project ID
 	ProjectID = getProjectID()
+
+	// ServiceName - Google App Engine service name
+	// Deprecated
+	ServiceName = os.Getenv(EnvKeyServiceName)
+
+	// ServiceVersion - Google App Engine service version
+	// Deprecated
+	ServiceVersion = os.Getenv(EnvKeyServiceVersion)
+
 	// GAEServiceName - Google App Engine service name
 	GAEServiceName = os.Getenv(EnvKeyGAEServiceName)
 	// GAEServiceVersion - Google App Engine service version
@@ -34,6 +43,14 @@ func getProjectID() string {
 // Reload - Reload environment variables.
 func Reload() {
 	ProjectID = getProjectID()
+
+	// Deprecated
+	// ServiceName - Deprecated
+	ServiceName = os.Getenv(EnvKeyServiceName)
+	// Deprecated
+	// ServiceVersion - Deprecated
+	ServiceVersion = os.Getenv(EnvKeyServiceVersion)
+
 	GAEServiceName = os.Getenv(EnvKeyGAEServiceName)
 	GAEServiceVersion = os.Getenv(EnvKeyGAEServiceVersion)
 	RUNServiceName = os.Getenv(EnvKeyRUNServiceName)

environ_test.go

@@ -26,6 +26,16 @@ func TestEnviron(t *testing.T) {
 	if ProjectID != testProject {
 		t.Fatalf("unexpected, expected: %s, actual: %#v", testProject, ProjectID)
 	}
+
+	// Deprecated
+	if ServiceName != testGAEService {
+		t.Fatalf("unexpected, expected: %s, actual: %#v", testGAEService, ServiceName)
+	}
+	// Deprecated
+	if ServiceVersion != testGAEVersion {
+		t.Fatalf("unexpected, expected: %s, actual: %#v", testGAEVersion, ServiceVersion)
+	}
+
 	if GAEServiceName != testGAEService {
 		t.Fatalf("unexpected, expected: %s, actual: %#v", testGAEService, GAEServiceName)
 	}