Module socket not found lua

Question

I am trying to use Lua to access Redis values from nginx. When I execute Lua files on the command line, I can read and write values to Redis. But when I try to execute the same files from nginx by accessing a location in which the access_by_lua directive is written, the following errors are logged in the error log file

no field package.preload['socket'] 
no file '/home/sivag/redis/redis-lua/src/socket.lua'
no file 'src/socket.lua'
no file '/home/sivag/lua/socket.lua'
no file '/opt/openresty/lualib/socket.so'
no file './socket.so'
no file '/usr/local/lib/lua/5.1/socket.so'
no file '/opt/openresty/luajit/lib/lua/5.1/socket.so'
no file '/usr/local/lib/lua/5.1/loadall.so'

What is the reason for this and how can I resolve this?

Answer 1

In my case I just needed to install the lua-socket package, as the socket library is not built into the default Lua installation like it is in some other languages.