Setup-OpenResty.md

Installing Lua-Cabsin on OpenResty

Installing OpenResty

You can follow this guide to install OpenResty on Ubuntu 20.04 if you have not yet installed it.

Installing and configuring LuaRocks

Run these commands in your terminal to install LuaRocks:

wget https://luarocks.org/releases/luarocks-3.3.1.tar.gz
tar zxpf luarocks-3.3.1.tar.gz
cd luarocks-3.3.1

To configure LuaRocks for OpenResty, run this command:

./configure --prefix=/usr/local/openresty/luajit \
--with-lua=/usr/local/openresty/luajit/ \
--lua-suffix=jit-2.1.0-beta3 \
--with-lua-include=/usr/local/openresty/luajit/include/luajit-2.1

and then this:

sudo make
sudo make install

NOTE:

• This is assuming OpenResty (not the executable) is installed at /usr/local/, if it isn't so - replace /usr/local/ with file path you have installed it in.
• Also assumed is that LuaJIT version is 2.1.0-beta3, you can check which LuaJIT version it is by doing: cd /usr/local/openresty/luajit/share/ and then ls. It will list a luajit folder like luajit-2.1.0-beta3, the suffix here is jit-2.1.0-beta3. If this isn't so, replace the suffix accordingly.

Installing dependencies

You need to install GCC and PCRE as these are dependencies for lualogging module and lrexlib-pcre module.

To do so:

sudo apt update
sudo apt install gcc
sudo apt install libpcre3 libpcre3-dev

NOTE: If you use yum you could use pcre and pcre-devel for PCRE.

Install LuaRocks modules

Run these commands to install the LuaRocks modules dependencies:

sudo /usr/local/openresty/luajit/bin/luarocks install lualogging
sudo /usr/local/openresty/luajit/bin/luarocks install lrexlib-pcre
sudo /usr/local/openresty/luajit/bin/luarocks install luaposix

NOTE: Here too the LuaRocks has its executable at /usr/local/openresty/luajit/bin/luarocks, if you have it installed somewhere else for OpenResty replace with that instead.

Using Lua-Casbin

Since the project isn't a LuaRocks/OPM module yet, you need to clone it to use it.

NOTE: You may need to add the nginx command to your path by adding export PATH="/usr/local/openresty/nginx/sbin/:$PATH" to your .bashrc or similar file. You can create a lua module for OpenResty applications as shown here or add it to your existing lua module by following these steps:

• In your module, clone the Lua Casbin repo at the top level (/) of your application (along with the conf directory) with git clone https://github.com/casbin/lua-casbin.git.
• In your module's conf/nginx.conf file append the lua_package_path with $prefix/lua-casbin/?.lua; so that it becomes something like this: lua_package_path "$prefix/lua/?.lua;$prefix/lua-casbin/?.lua;;";.
• In the file where you want to use Casbin, use local Enforcer = require("src/main/Enforcer") inside the content_by_lua_block. Here is a sample describing usage for basic model/policy and ABAC model/policy:

Basic model/policy example (nginx.conf file)

worker_processes 1;

events {
    worker_connections 1024;
}

http {
    lua_package_path "$prefix/lua/?.lua;$prefix/lua-casbin/?.lua;;";

    server {
        listen 8080 reuseport;

        location / {
            default_type text/plain;
            content_by_lua_block {
                local Enforcer = require("src.main.Enforcer")
                local model  = "lua-casbin/examples/basic_model.conf" -- The model file path
                local policy  = "lua-casbin/examples/basic_policy.csv" -- The policy file path
                
                local e = Enforcer:new(model, policy) -- The Casbin Enforcer
                ngx.say("The result is:")
                ngx.say(e:enforce("alice", "data1", "read")) -- The enforce function with its arguments
            }
        }
    }
}

ABAC model/policy example (nginx.conf file)

worker_processes 1;

events {
    worker_connections 1024;
}

http {
    lua_package_path "$prefix/lua/?.lua;$prefix/lua-casbin/?.lua;;";

    server {
        listen 8080 reuseport;

        location / {
            default_type text/plain;
            content_by_lua_block {
                local Enforcer = require("src.main.Enforcer")
                local model  = "lua-casbin/examples/abac_rule_model.conf"
    		local policy  = "lua-casbin/examples/abac_rule_policy.csv"
    		local sub1 = {
        		Name = "Alice",
        		Age = 16
    		}
    		local sub2 = {
        		Name = "Bob",
        		Age = 20
    		}
    		local sub3 = {
        		Name = "Alice",
        		Age = 65
    		}
    		local e = Enforcer:new(model, policy)
    		ngx.say("The result is:")
    		ngx.say(e:enforce(sub2, "/data1", "read"))
            }
        }
    }
}

Then use nginx -p $PWD/ to start the server and use curl http://127.0.0.1:8080/ to fetch the page which for the above examples should output in:

The result is:
true

You can check other examples here and the Built-In Functions currently supported here.