Using NGINX with ngx_lua can help you write more performant applications. Instead of passing logic to an upstream server, Lua can handle this processing. The ngx_lua module can be invoked at different phases of NGINX request processing.
Many of the ngx_lua configuration directives directly reference the phase of the request that they affect. For instance, there will be init_by_lua, init_worker_by_lua, content_by_lua, rewrite_by_lua, access_by_lua, header_filter_by_lua, body_filter_by_lua, and log_by_lua to do something with Lua at that phase of the request. Depending on where in the request processing chain you want to use Lua, you use the corresponding directive.
Loading a Lua script to handle a request involves using the lua_package_path directive to specify the location in which to find the script, and then using the appropriate _by_lua directive to execute the script:
lua_package_path "$prefixlib/?.lua;;";
server {
location / {
content_by_lua_block...