feat: add environ

Author: 54m

environ.go

@@ -0,0 +1,35 @@
+package gcpen
+
+import (
+	"os"
+)
+
+var (
+	// ProjectID - Google Cloud Platform Project ID
+	ProjectID = getProjectID()
+	// ServiceName - Google App Engine service name
+	ServiceName = os.Getenv(EnvKeyServiceName)
+	// ServiceVersion - Google App Engine service version
+	ServiceVersion = os.Getenv(EnvKeyServiceVersion)
+)
+
+func getProjectID() string {
+	id, ok := os.LookupEnv(EnvKeyProjectID)
+	if ok {
+		return id
+	}
+
+	id, ok = os.LookupEnv(EnvKeyGoogleCloudProject)
+	if ok {
+		return id
+	}
+
+	return ""
+}
+
+// Reload - Reload environment variables.
+func Reload() {
+	ProjectID = getProjectID()
+	ServiceName = os.Getenv(EnvKeyServiceName)
+	ServiceVersion = os.Getenv(EnvKeyServiceVersion)
+}