MM-11384: Add system install date information to the client config (#9218)

* MM-11384: Add system install date information to the client config

* Fixing translation text

* Fixes from Peer Review

app/app.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"path"
 	"reflect"
+	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -212,6 +213,10 @@ func New(options ...Option) (outApp *App, outErr error) {
 		return nil, errors.Wrapf(err, "unable to ensure asymmetric signing key")
 	}
 
+	if err := app.ensureInstallationDate(); err != nil {
+		return nil, errors.Wrapf(err, "unable to ensure installation date")
+	}
+
 	app.EnsureDiagnosticId()
 	app.regenerateClientConfig()
 
@@ -740,3 +745,16 @@ func (a *App) StartElasticsearch() {
 		}
 	})
 }
+
+func (a *App) getSystemInstallDate() (int64, *model.AppError) {
+	result := <-a.Srv.Store.System().GetByName(model.SYSTEM_INSTALLATION_DATE_KEY)
+	if result.Err != nil {
+		return 0, result.Err
+	}
+	systemData := result.Data.(*model.System)
+	value, err := strconv.ParseInt(systemData.Value, 10, 64)
+	if err != nil {
+		return 0, model.NewAppError("getSystemInstallDate", "app.system_install_date.parse_int.app_error", nil, err.Error(), http.StatusInternalServerError)
+	}
+	return value, nil
+}