语法: value = ngx.is_subrequest
环境: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua**
如果当前请求是 nginx 子请求返回 true ，否则返回 false 。
English source:
syntax: value = ngx.is_subrequest
context: set_by_lua, rewrite_by_lua*, access_by_lua*, content_by_lua*, header_filter_by_lua*, body_filter_by_lua*, log_by_lua**
Returns true if the current request is an nginx subrequest, or false otherwise.