[MM-14400] Programmatically generate default.json (#10551)

* create/update config.json using go generate

* added default config generator
added config-reset to Jenkins and make package, updated defaults to consider 'isNew' flag

* corrections after code review

* fixed Config.isValid to handle empty encryption keys

* fixed Config.isValid to handle empty encryption keys

* fixed Config.isValid to handle empty encryption keys

* isUpdate now only checks for nil

* Addressed review comments, added unit testing for default config generator

* err shadowing

* license

* provide output file for config generator via ENV variable, since go generate doesn't support arguments and we need two output paths (config-reset and package)

* cleanup

* proper defaults for PushNotificationServer and SendPushNotifications

* corrected generating defaults for TrustedProxyIPHeader to be consistent with default.json in master

* Check for empty SiteURL as well as nil

* corrected SiteURL settings and checking

* crazy typos fixed

* corrected tests to newly expected values

* relaxed the checks

* fixed formatting

config/default_test.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package config
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/mattermost/mattermost-server/model"
+
+	"github.com/mattermost/mattermost-server/config/config_generator/generator"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDefaultsGenerator(t *testing.T) {
+	tmpFile, err := ioutil.TempFile("", "tempconfig")
+	defer os.Remove(tmpFile.Name())
+	require.NoError(t, err)
+	require.NoError(t, generator.GenerateDefaultConfig(tmpFile))
+	_ = tmpFile.Close()
+	var config model.Config
+
+	b, err := ioutil.ReadFile(tmpFile.Name())
+	require.NoError(t, err)
+	require.NoError(t, json.Unmarshal(b, &config))
+	require.True(t, *config.ServiceSettings.DisableLegacyMFA)
+	require.Equal(t, *config.SqlSettings.AtRestEncryptKey, "")
+	require.Equal(t, *config.FileSettings.PublicLinkSalt, "")
+
+	require.Equal(t, *config.Office365Settings.Scope, model.OFFICE365_SETTINGS_DEFAULT_SCOPE)
+	require.Equal(t, *config.Office365Settings.AuthEndpoint, model.OFFICE365_SETTINGS_DEFAULT_AUTH_ENDPOINT)
+	require.Equal(t, *config.Office365Settings.UserApiEndpoint, model.OFFICE365_SETTINGS_DEFAULT_USER_API_ENDPOINT)
+	require.Equal(t, *config.Office365Settings.TokenEndpoint, model.OFFICE365_SETTINGS_DEFAULT_TOKEN_ENDPOINT)
+
+	require.Equal(t, *config.GoogleSettings.Scope, model.GOOGLE_SETTINGS_DEFAULT_SCOPE)
+	require.Equal(t, *config.GoogleSettings.AuthEndpoint, model.GOOGLE_SETTINGS_DEFAULT_AUTH_ENDPOINT)
+	require.Equal(t, *config.GoogleSettings.UserApiEndpoint, model.GOOGLE_SETTINGS_DEFAULT_USER_API_ENDPOINT)
+	require.Equal(t, *config.GoogleSettings.TokenEndpoint, model.GOOGLE_SETTINGS_DEFAULT_TOKEN_ENDPOINT)
+}