feat: add database size metric

repositories/metrics.go

@@ -0,0 +1,43 @@
+package repositories
+
+import (
+	"github.com/muety/wakapi/config"
+	"gorm.io/gorm"
+)
+
+type MetricsRepository struct {
+	config *config.Config
+	db     *gorm.DB
+}
+
+const sizeTplMysql = `
+SELECT SUM(data_length + index_length)
+FROM information_schema.tables
+WHERE table_schema = ?
+GROUP BY table_schema`
+
+const sizeTplPostgres = `SELECT pg_database_size('%s');`
+
+const sizeTplSqlite = `
+SELECT page_count * page_size as size
+FROM pragma_page_count(), pragma_page_size();`
+
+func NewMetricsRepository(db *gorm.DB) *MetricsRepository {
+	return &MetricsRepository{config: config.Get(), db: db}
+}
+
+func (srv *MetricsRepository) GetDatabaseSize() (size int64, err error) {
+	cfg := srv.config.Db
+
+	query := srv.db.Raw("SELECT 0")
+	if cfg.IsMySQL() {
+		query = srv.db.Raw(sizeTplMysql, cfg.Name)
+	} else if cfg.IsPostgres() {
+		query = srv.db.Raw(sizeTplPostgres, cfg.Name)
+	} else if cfg.IsSQLite() {
+		query = srv.db.Raw(sizeTplSqlite)
+	}
+
+	err = query.Scan(&size).Error
+	return size, err
+}