序

本文主要研究下如何在openresty下lua的function定义及调用。

源码示例

/usr/local/openresty/lualib/resty/string.lua

-- Copyright (C) by Yichun Zhang (agentzh)local ffi = require "ffi"local ffi_new = ffi.newlocal ffi_str = ffi.stringlocal C = ffi.Clocal setmetatable = setmetatablelocal error = errorlocal tonumber = tonumberlocal _M = { _VERSION = '0.09' }ffi.cdef[[typedef unsigned char u_char;u_char * ngx_hex_dump(u_char *dst, const u_char *src, size_t len);intptr_t ngx_atoi(const unsigned char *line, size_t n);]]local str_type = ffi.typeof("uint8_t[?]")function _M.to_hex(s)    local len = #s * 2    local buf = ffi_new(str_type, len)    C.ngx_hex_dump(buf, s, #s)    return ffi_str(buf, len)endfunction _M.atoi(s)    return tonumber(C.ngx_atoi(s, #s))endreturn _M

实例

demo.lua

local _M = { _VERSION = '0.01' }function _M.hello()    ngx.say("hello from demo module!")endreturn _M

conf

location /function {            content_by_lua '                local demo = require("demo")                demo.hello()            ';        }

报错

2018/03/26 16:24:15 [error] 5#5: *1 lua entry thread aborted: runtime error: content_by_lua(nginx.conf:69):2: module 'demo' not found:    no field package.preload['demo']    no file '/usr/local/openresty/lualib/demo.lua'    no file '/usr/local/openresty/lualib/demo/init.lua'    no file './demo.lua'    no file '/usr/local/openresty/luajit/share/luajit-2.1.0-beta2/demo.lua'    no file '/usr/local/share/lua/5.1/demo.lua'    no file '/usr/local/share/lua/5.1/demo/init.lua'    no file '/usr/local/openresty/luajit/share/lua/5.1/demo.lua'    no file '/usr/local/openresty/luajit/share/lua/5.1/demo/init.lua'    no file '/usr/local/openresty/lualib/demo.so'    no file './demo.so'    no file '/usr/local/lib/lua/5.1/demo.so'    no file '/usr/local/openresty/luajit/lib/lua/5.1/demo.so'    no file '/usr/local/lib/lua/5.1/loadall.so'stack traceback:coroutine 0:    [C]: in function 'require'    content_by_lua(nginx.conf:69):2: in function 
    
     , client: 192.168.99.1, server: , request: "GET /function HTTP/1.1", host: "192.168.99.100:8686"
    

修复

ADD demo.lua /usr/local/openresty/lualib/demo.lua

小结

从源码可以看出，基本是定义一个_M变量，里头有个_VERSION属性，然后定义_M的function，最后返回_M。另外注意自己定义的类库需要放在openresty查找的路径下面，否则会报错。

doc