openresty
- The *by_lua modules that tweak the nginx behaviour (for ex the rewrite_by_lua that is the lua equivalent of nginx http rewrite) module are always run after the standard nginx modules.
- The choice of *by_lua module to use largely depends upon the problem that you are trying to solve. For example the init_by_lua module is used for initialization operations where as access_by_lua may be used to implement access policies for a location block. Personally among the various directives I find most use for content_by_lua.
From http://www.staticshin.com/programming/definitely-an-open-resty-guide/
http://www.londonlua.org/scripting_nginx_with_lua/slides.html
Lua can access nginx at different phase, the most important directives are:
Rewrite_by_lua
Access_by_lua
Content_by_lua
Init_by_lua
Set_by_lua
Rememeber to set lua_code_cache when developing
Use ngx.location.capture to issue a sub-request to other locations in nginx
ngx.ctx is a lua table to store data with a lifetime