Merge pull request #4 from mackerelio/supported-version-mysql57-or-more

Supported version MySQL 5.7 or more

Author: yseto

README.md

@@ -16,3 +16,6 @@ mackerel-plugin-mysql [-host=<host>] [-port=<port>] [-username=<username>] [-pas
 command = "/path/to/mackerel-plugin-mysql"
 ```
 
+## Supported MySQL version
+
+mysql 5.7, 8.0 and above

lib/mysql.go

@@ -231,29 +231,13 @@ func (m *MySQLPlugin) fetchShowInnodbStatus(db *sql.DB, stat map[string]float64)
 	}
 	defer rows.Close()
 
-	columns, err := rows.Columns()
-	if err != nil {
-		return fmt.Errorf("FetchMetrics (fetchShowInnodbStatus): error: %w", err)
-	}
-
-	// when mysql 5.0, return result 1 column.
-	// when more than mysql 5.1, return result 3 columns.
-	count := len(columns)
-	scanner := make([]interface{}, count)
-	scannerPtr := make([]interface{}, count)
-	for i := range columns {
-		scannerPtr[i] = &scanner[i]
-	}
-
 	for rows.Next() {
-		if err := rows.Scan(scannerPtr...); err != nil {
+		var status string
+		if err = rows.Scan(trashScanner{}, trashScanner{}, &status); err != nil {
 			return fmt.Errorf("FetchMetrics (fetchShowInnodbStatus): error: %w", err)
 		}
 
-		c, ok := scanner[count-1].([]byte)
-		if ok {
-			parseInnodbStatus(string(c), stat)
-		}
+		parseInnodbStatus(status, stat)
 	}
 	return nil
 }
@@ -411,6 +395,15 @@ func (m *MySQLPlugin) FetchMetrics() (map[string]float64, error) {
 	}
 	defer db.Close()
 
+	v, err := m.fetchVersion(db)
+	if err != nil {
+		log.Println(err)
+	} else {
+		if v[0] < 5 || v[0] == 5 && v[1] < 7 {
+			log.Fatalln("This mysql server version is not supported.")
+		}
+	}
+
 	stat := make(map[string]float64)
 	err = m.fetchShowStatus(db, stat)
 	if err != nil {