Remove "CHARSET" config option for MySQL, always use "utf8mb4" (#25413)

In modern days, there is no reason to make users set "charset" anymore.

Close #25378

## :warning: BREAKING

The key `[database].CHARSET` was removed completely as every newer
(>10years) MySQL database supports `utf8mb4` already.
There is a (deliberately) undocumented new fallback option if anyone
still needs to use it, but we don't recommend using it as it simply
causes problems.

1 files changed, 9 insertions, 19 deletions

diff --git a/modules/setting/database.go b/modules/setting/database.go
index 7a7c7029a4..709655368c 100644
--- a/modules/setting/database.go
+++ b/modules/setting/database.go
@@ -12,8 +12,6 @@ import (
 	"path/filepath"
 	"strings"
 	"time"
-
-	"code.gitea.io/gitea/modules/log"
 )
 
 var (
@@ -36,7 +34,7 @@ var (
 		SSLMode           string
 		Path              string
 		LogSQL            bool
-		Charset           string
+		MysqlCharset      string
 		Timeout           int // seconds
 		SQLiteJournalMode string
 		DBConnectRetries  int
@@ -60,11 +58,6 @@ func LoadDBSetting() {
 func loadDBSetting(rootCfg ConfigProvider) {
 	sec := rootCfg.Section("database")
 	Database.Type = DatabaseType(sec.Key("DB_TYPE").String())
-	defaultCharset := "utf8"
-
-	if Database.Type.IsMySQL() {
-		defaultCharset = "utf8mb4"
-	}
 
 	Database.Host = sec.Key("HOST").String()
 	Database.Name = sec.Key("NAME").String()
@@ -74,10 +67,7 @@ func loadDBSetting(rootCfg ConfigProvider) {
 	}
 	Database.Schema = sec.Key("SCHEMA").String()
 	Database.SSLMode = sec.Key("SSL_MODE").MustString("disable")
-	Database.Charset = sec.Key("CHARSET").In(defaultCharset, []string{"utf8", "utf8mb4"})
-	if Database.Type.IsMySQL() && defaultCharset != "utf8mb4" {
-		log.Error("Deprecated database mysql charset utf8 support, please use utf8mb4 or convert utf8 to utf8mb4.")
-	}
+	Database.MysqlCharset = sec.Key("MYSQL_CHARSET").MustString("utf8mb4") // do not document it, end users won't need it.
 
 	Database.Path = sec.Key("PATH").MustString(filepath.Join(AppDataPath, "gitea.db"))
 	Database.Timeout = sec.Key("SQLITE_TIMEOUT").MustInt(500)
@@ -101,9 +91,9 @@ func loadDBSetting(rootCfg ConfigProvider) {
 // DBConnStr returns database connection string
 func DBConnStr() (string, error) {
 	var connStr string
-	Param := "?"
-	if strings.Contains(Database.Name, Param) {
-		Param = "&"
+	paramSep := "?"
+	if strings.Contains(Database.Name, paramSep) {
+		paramSep = "&"
 	}
 	switch Database.Type {
 	case "mysql":
@@ -116,15 +106,15 @@ func DBConnStr() (string, error) {
 			tls = "false"
 		}
 		connStr = fmt.Sprintf("%s:%s@%s(%s)/%s%scharset=%s&parseTime=true&tls=%s",
-			Database.User, Database.Passwd, connType, Database.Host, Database.Name, Param, Database.Charset, tls)
+			Database.User, Database.Passwd, connType, Database.Host, Database.Name, paramSep, Database.MysqlCharset, tls)
 	case "postgres":
-		connStr = getPostgreSQLConnectionString(Database.Host, Database.User, Database.Passwd, Database.Name, Param, Database.SSLMode)
+		connStr = getPostgreSQLConnectionString(Database.Host, Database.User, Database.Passwd, Database.Name, paramSep, Database.SSLMode)
 	case "mssql":
 		host, port := ParseMSSQLHostPort(Database.Host)
 		connStr = fmt.Sprintf("server=%s; port=%s; database=%s; user id=%s; password=%s;", host, port, Database.Name, Database.User, Database.Passwd)
 	case "sqlite3":
 		if !EnableSQLite3 {
-			return "", errors.New("this binary version does not build support for SQLite3")
+			return "", errors.New("this Gitea binary was not built with SQLite3 support")
 		}
 		if err := os.MkdirAll(path.Dir(Database.Path), os.ModePerm); err != nil {
 			return "", fmt.Errorf("Failed to create directories: %w", err)
@@ -136,7 +126,7 @@ func DBConnStr() (string, error) {
 		connStr = fmt.Sprintf("file:%s?cache=shared&mode=rwc&_busy_timeout=%d&_txlock=immediate%s",
 			Database.Path, Database.Timeout, journalMode)
 	default:
-		return "", fmt.Errorf("Unknown database type: %s", Database.Type)
+		return "", fmt.Errorf("unknown database type: %s", Database.Type)
 	}
 
 	return connStr, nil