fix(fork): backport k3s-io/kine#795 Migrate connection leak fix

pkg/drivers/generic/generic.go

@@ -106,16 +106,13 @@ type Generic struct {
 }
 
 func (d *Generic) Migrate(ctx context.Context) {
-	var (
-		count     = 0
-		countKV   = d.queryRow(ctx, query.New("SELECT COUNT(*) FROM key_value", "?", false, ""))
-		countKine = d.queryRow(ctx, query.New("SELECT COUNT(*) FROM kine", "?", false, ""))
-	)
+	var count int
 
+	countKV := d.queryRow(ctx, query.New("SELECT COUNT(*) FROM key_value", "?", false, ""))
 	if err := countKV.Scan(&count); err != nil || count == 0 {
 		return
 	}
-
+	countKine := d.queryRow(ctx, query.New("SELECT COUNT(*) FROM kine", "?", false, ""))
 	if err := countKine.Scan(&count); err != nil || count != 0 {
 		return
 	}

pkg/drivers/sqlite/sqlite_test.go

@@ -1,9 +1,15 @@
 package sqlite
 
 import (
+	"context"
 	"database/sql"
 	"path/filepath"
+	"sync"
 	"testing"
+	"time"
+
+	"github.com/k3s-io/kine/pkg/drivers"
+	"github.com/k3s-io/kine/pkg/drivers/generic"
 )
 
 // createBloatedDB creates a temporary SQLite database in WAL mode with the kine
@@ -148,3 +154,25 @@ func TestSetupVacuumDisabledPreservesFileSize(t *testing.T) {
 
 	t.Logf("No VACUUM: freelist pages before=%d, after=%d", freelistBefore, freelistAfter)
 }
+
+func TestMigrateReleasesItsConnections(t *testing.T) {
+	var wg sync.WaitGroup
+	_, dialect, err := NewVariant(t.Context(), &wg, "sqlite3", &drivers.Config{
+		DataSourceName: filepath.Join(t.TempDir(), "test.db") + "?" + DefaultParams,
+		// Use a single connection to catch any connection leaks in Migrate
+		ConnectionPoolConfig: generic.ConnectionPoolConfig{
+			MaxOpen: 1,
+			MaxIdle: 1,
+		},
+	})
+	if err != nil {
+		t.Fatalf("failed to create dialect: %v", err)
+	}
+	t.Cleanup(wg.Wait)
+
+	ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
+	defer cancel()
+	if _, err := dialect.DB.ExecContext(ctx, `SELECT 1`); err != nil {
+		t.Fatalf("database unusable after Migrate: %v", err)
+	}
+}