Config migrate SAML keys and certificates (#11596)

config/migrate.go

@@ -0,0 +1,52 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package config
+
+import "github.com/pkg/errors"
+
+func Migrate(from, to string) error {
+	source, err := NewStore(from, false)
+	if err != nil {
+		return errors.Wrapf(err, "failed to access source config %s", from)
+	}
+
+	destination, err := NewStore(to, false)
+	if err != nil {
+		return errors.Wrapf(err, "failed to access destination config %s", to)
+	}
+
+	sourceConfig := source.Get()
+	if _, err = destination.Set(sourceConfig); err != nil {
+		return errors.Wrapf(err, "failed to set config")
+	}
+
+	files := []string{*sourceConfig.SamlSettings.IdpCertificateFile, *sourceConfig.SamlSettings.PublicCertificateFile,
+		*sourceConfig.SamlSettings.PrivateKeyFile}
+
+	for _, file := range files {
+		err = migrateFile(file, source, destination)
+
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func migrateFile(name string, source Store, destination Store) error {
+	fileExists, err := source.HasFile(name)
+	if err != nil {
+		return errors.Wrapf(err, "failed to check existence of %s", name)
+	}
+
+	if fileExists {
+		file, err := source.GetFile(name)
+		err = destination.SetFile(name, file)
+		if err != nil {
+			return errors.Wrapf(err, "failed to migrate %s", name)
+		}
+	}
+
+	return nil
+}