Nginx + Lua + Redis. Effectively process the session and give the data

Suppose you have data that you want to cache and give away without using heavy languages ​​like php , while checking that the user is authenticated and has the right to access the data. Today I will tell you how, using the nginx lua redis bundle , to accomplish this task, unload the server and increase the speed at which the server returns information tenfold.

First you need to build nginx with the nginx_lua_module module .



In order to quickly and efficiently give cached data, we will put the most frequently used ones in redis right after warming up the cache, and we will put less used ones on request. We will give data using lua on the side of nginx . Php will not be involved in this bundle, which will speed up data output and will take up much less memory from the server.

To do this, write the Lua script.



Connect this file to nginx.conf and reboot nginx

 location /search-by-string { content_by_lua_file lua/search.lua; } 

Now when you query / search-by-string? String = smth lua will connect to redis and try to find the data using the search: smth key . If there is no data, the request will process php . But if the data is already cached and are in redis , they will immediately be given to the user.

But what if we need to give data only if the user is authenticated and at the same time has a certain role?

In this case, you can store the session in redis and before giving the content, check the user's role according to the session.

Since I work with the Symfony2 framework, then a small nginx-session-handler bundle was written for it, with which you can store the session in redis exactly as it suits us.

In redis, the data will be stored as a hash value:
phpsession - session key prefix
php-session - php session itself
user-role - user role.

Now you need to write a lua script to process this data:



We retrieve the session id of the user from the cookie, trying to get the role of the user by its session id from the redis at the request of HGET phpsession: id user-role . If the user has expired the session, he is not authenticated, or he does not have the role of ROLE_ADMIN, the server will return the code 403.

We add this session processing script to our data retrieval script and now only authenticated users with the ROLE_ADMIN role can receive data.

In fact, a session processing script will be required for multiple nginx locations. In order not to write the same code in different places, we will include this file where we need it.

First, let's rewrite our session processing script.



Now you need to build the session.o file from session.lua using the luaJit compiler and build nginx with this file.

Compile the session.o file by executing the lua compiler command

 /path/to/luajit/bin/luajit -bg session.lua session.o 

Add a line to the configuration to build nginx

 --with-ld-opt="/path/to/session.o" 

and collect nginx (how to build nginx described above)

After that, you can connect the file to any lua script and call the handle () function to process the user session

 local session = require "session" session.handle() 

At the end of a small test for comparison.


Tests that extract data from redis using php or lua



The difference in the "number of requests per second" is 175 times.

The same test with other parameters


The difference in the "number of requests per second" is 381 times.

Hope my article was helpful. If you have any wishes, remarks or you know how to do better - write.