Feature Request: ability to intentionally fail nginx loading by lua code

It would be useful to fail configuration loading from lua code, like in init_by_lua.

For example, we are building a system based on OpenResty, which has its own configuration, loaded when OpenResty starts. We load configuration in init_bu_lua so we can take advantages like COW, and rely on -s reload to reload new configuration for the system.

We use error() to fail loading when configuration is malformed, which terminates loading process and stop OpenResty from start.

The solution above has two problem: It prints traceback which mess up the error log, and it won't report any problem when -s reload. We didn't find a way to tell nginx that it fails to configurate, like any directive reciving bad arguments.

Start by tracing the init_by_lua configuration-loading path and how nginx handles -s reload. The requested behavior is an intentional configuration failure from Lua without a traceback, with the failure reported during reload as it is for invalid directive arguments.