nginx_lua_rewrite_response_sample.cfg

        location /lua_return_404 {
                set $body "";
                rewrite_by_lua '
                        ngx.exit(404)
                ';
                header_filter_by_lua_block {
                        local body = "{ \"http_host\": \"" .. ngx.var.http_host .. "\" }"
                        ngx.var.body = body
                        local body_length = string.len(body)

                        ngx.header.content_type = "application/json"
                        ngx.header.content_length = body_length
                }
                body_filter_by_lua_block {
                        ngx.arg[1] = ngx.var.body
                        ngx.arg[2] = true
                }
        }