Exclude system databases during backup (#716)

Signed-off-by: hmsayem <hmsayem@appscode.com>

Author: hmsayem

pkg/backup.go

@@ -18,6 +18,7 @@ package pkg
 
 import (
 	"context"
+	"fmt"
 	"path/filepath"
 
 	api_v1beta1 "stash.appscode.dev/apimachinery/apis/stash/v1beta1"
@@ -219,6 +220,17 @@ func (opt *mysqlOptions) backupMySQL(targetRef api_v1beta1.TargetRef) (*restic.B
 		return nil, err
 	}
 
+	databases, err := session.fetchNonSystemDatabases()
+	if err != nil {
+		return nil, err
+	}
+
+	if len(databases) == 0 {
+		return nil, fmt.Errorf("unable to find any databases for backup")
+	}
+
+	session.setTargetDatabases(databases)
+
 	session.setUserArgs(opt.myArgs)
 
 	// add backup command in the pipeline

pkg/restore.go

@@ -161,7 +161,7 @@ func (opt *mysqlOptions) restoreMySQL(targetRef api_v1beta1.TargetRef) (*restic.
 		return nil, err
 	}
 
-	session := opt.newSessionWrapper(MySqlRestoreCMD)
+	session := opt.newSessionWrapper(MySqlCMD)
 
 	err = session.setDatabaseCredentials(opt.kubeClient, appBinding)
 	if err != nil {

pkg/utils.go

@@ -43,7 +43,7 @@ const (
 	MySqlPassword    = "password"
 	MySqlDumpFile    = "dumpfile.sql"
 	MySqlDumpCMD     = "mysqldump"
-	MySqlRestoreCMD  = "mysql"
+	MySqlCMD         = "mysql"
 	EnvMySqlPassword = "MYSQL_PWD"
 )
 
@@ -158,3 +158,39 @@ func (session sessionWrapper) waitForDBReady(waitTimeout int32) error {
 		return false, nil
 	})
 }
+
+func (session sessionWrapper) fetchNonSystemDatabases() ([]string, error) {
+	sh := shell.NewSession()
+	for k, v := range session.sh.Env {
+		sh.SetEnv(k, v)
+	}
+
+	args := append(session.cmd.Args, "--raw", "--execute", "show databases")
+	out, err := sh.Command(MySqlCMD, args...).Command("tail", "-n+2").Output()
+	if err != nil {
+		return nil, err
+	}
+
+	allDatabases := strings.Split(string(out), "\n")
+
+	var databases []string
+	for _, db := range allDatabases {
+		db := strings.TrimSpace(db)
+		if db != "" && !isSystemDatabase(db) {
+			databases = append(databases, db)
+		}
+	}
+
+	return databases, nil
+}
+
+func isSystemDatabase(db string) bool {
+	return db == "information_schema" || db == "mysql" || db == "performance_schema" || db == "sys"
+}
+
+func (session *sessionWrapper) setTargetDatabases(databases []string) {
+	session.cmd.Args = append(session.cmd.Args, "--databases")
+	for _, db := range databases {
+		session.cmd.Args = append(session.cmd.Args, db)
+	}
+}