Don't use 'stack' in static but use $USER.
diff --git a/files/swift-container-server.conf b/files/swift-container-server.conf
index c630076..8d59bf2 100644
--- a/files/swift-container-server.conf
+++ b/files/swift-container-server.conf
@@ -2,7 +2,7 @@
 devices = %NODE_PATH%/node
 mount_check = false
 bind_port = %BIND_PORT%
-user = stack
+user = %USER%
 log_facility = LOG_LOCAL%LOG_FACILITY%
 
 [pipeline:main]