什么是Luarocks

Luarocks是一个Lua包管理器，基于 Lua 语言开发，提供一个命令行的方式来管理 Lua 包依赖、安装第三方 Lua 包等，社区比较流行的包管理器之一

Python具有PIP，Ruby具有Gems，Java具有Maven，Node具有npm，Lua具有Luarocks。

前要：先看Lua的require

以openresty中的Luajit/usr/local/openresty/luajit/bin/luajit为例：

测试代码：

local cjson = require "cjson"
local s = cjson.encode({"test", "lua", "package"})
print(s)

执行结果：

/usr/local/openresty/luajit/bin/luajit: test.lua:3: module 'cjson' not found:
        no field package.preload['cjson']
        no file './cjson.lua'
        no file '/usr/local/openresty/luajit/share/luajit-2.1.0-beta3/cjson.lua'
        no file '/usr/local/share/lua/5.1/cjson.lua'
        no file '/usr/local/share/lua/5.1/cjson/init.lua'
        no file '/usr/local/openresty/luajit/share/lua/5.1/cjson.lua'
        no file '/usr/local/openresty/luajit/share/lua/5.1/cjson/init.lua'
        no file './cjson.so'
        no file '/usr/local/lib/lua/5.1/cjson.so'
        no file '/usr/local/openresty/luajit/lib/lua/5.1/cjson.so'
        no file '/usr/local/lib/lua/5.1/loadall.so'
stack traceback:
        [C]: in function 'require'
        test.lua:3: in main chunk
        [C]: at 0x004055d0

从测试结果可以看到，require有几个搜索目录，理论上任意目录都可以

Luarocks包管理

我们软件开发过程中会引入大量库。如果简单把所有库都放入代码仓，那会造成大量的混乱。因此，更适合的办法是，使用luarocks包管理工具，将库安装到库目录。

示例：luarocks 安装 cjson

以openresty中的Luajit/usr/local/openresty/luajit/bin/luajit为例：

/usr/local/openresty/luajit/bin/luarocks install lua-cjson

Installing /luarocks.org/lua-cjson-2.1.0.10-1.src.rock

lua-cjson 2.1.0.10-1 depends on lua >= 5.1 (5.1-1 provided by VM)
gcc -O2 -fPIC -I/usr/local/openresty/luajit/include/luajit-2.1 -c lua_cjson.c -o lua_cjson.o
gcc -O2 -fPIC -I/usr/local/openresty/luajit/include/luajit-2.1 -c strbuf.c -o strbuf.o
gcc -O2 -fPIC -I/usr/local/openresty/luajit/include/luajit-2.1 -c fpconv.c -o fpconv.o
gcc -shared -o cjson.so lua_cjson.o strbuf.o fpconv.o
No existing manifest. Attempting to rebuild...
lua-cjson 2.1.0.10-1 is now installed in /usr/local/openresty/luajit (license: MIT)

# find /usr/local/openresty/luajit -name cjson.so 
/usr/local/openresty/luajit/lib/lua/5.1/cjson.so

luarocks 安装nettle

# find /usr/local/openresty/luajit -name *nettle*
/usr/local/openresty/luajit/lib/luarocks/rocks-5.1/lua-resty-nettle
/usr/local/openresty/luajit/lib/luarocks/rocks-5.1/lua-resty-nettle/2.1-1/lua-resty-nettle-2.1-1.rockspec
/usr/local/openresty/luajit/share/lua/5.1/resty/nettle
/usr/local/openresty/luajit/share/lua/5.1/resty/nettle/types/nettle-types.lua
/usr/local/openresty/luajit/share/lua/5.1/resty/nettle.lua