根据配置文件加载插件

编写加载配置文件的方法,来读取识别conf/fago.conf 配置文件

一）编写读取配置文件内容的类库

---------------io.lua--------------------

--- 
-- :P some origin code is from https://github.com/Mashape/kong/blob/master/kong/tools/io.lua

local stringy = require("fago.common.stringy")

local _M = {}

---
-- Checks existence of a file.
-- @param path path/file to check
-- @return `true` if found, `false` + error message otherwise
function _M.file_exists(path)
    local f, err = io.open(path, "r")
    if f ~= nil then
        io.close(f)
        return true
    else
        return false, err
    end
end

---
-- Execute an OS command and catch the output.
-- @param command OS command to execute
-- @return string containing command output (both stdout and stderr)
-- @return exitcode
function _M.os_execute(command, preserve_output)
    local n = os.tmpname() -- get a temporary file name to store output
    local f = os.tmpname() -- get a temporary file name to store script
    _M.write_to_file(f, command)
    local exit_code = os.execute("/bin/bash "..f.." > "..n.." 2>&1")
    local result = _M.read_file(n)
    os.remove(n)
    os.remove(f)
    return preserve_output and result or string.gsub(string.gsub(result, "^"..f..":[%s%w]+:%s*", ""), "[%\r%\n]", ""), exit_code / 256
end

---
-- Check existence of a command.
-- @param cmd command being searched for
-- @return `true` of found, `false` otherwise
function _M.cmd_exists(cmd)
    local _, code = _M.os_execute("hash "..cmd)
    return code == 0
end

--- Kill a process by PID.
-- Kills the process and waits until it's terminated
-- @param pid_file the file containing the pid to kill
-- @param signal the signal to use
-- @return `os_execute` results, see os_execute.
function _M.kill_process_by_pid_file(pid_file, signal)
    if _M.file_exists(pid_file) then
        local pid = stringy.strip(_M.read_file(pid_file))
        return _M.os_execute("while kill -0 "..pid.." >/dev/null 2>&1; do kill "..(signal and "-"..tostring(signal).." " or "")..pid.."; sleep 0.1; done")
    end
end

--- Read file contents.
-- @param path filepath to read
-- @return file contents as string, or `nil` if not succesful
function _M.read_file(path)
    local contents
    local file = io.open(path, "rb")
    if file then
        contents = file:read("*all")
        file:close()
    end
    return contents
end

--- Write file contents.
-- @param path filepath to write to
-- @return `true` upon success, or `false` + error message on failure
function _M.write_to_file(path, value)
    local file, err = io.open(path, "w")
    if err then
        return false, err
    end

    file:write(value)
    file:close()
    return true
end


--- Get the filesize.
-- @param path path to file to check
-- @return size of file, or `nil` on failure
function _M.file_size(path)
    local size
    local file = io.open(path, "rb")
    if file then
        size = file:seek("end")
        file:close()
    end
    return size
end

return _M

二）编写针对字符串的工具类

-------------------stringy.lua-----------------------

local string_gsub = string.gsub
local string_find = string.find
local table_insert = table.insert

local _M = {}

function _M.trim_all(str)
    if not str or str == "" then return "" end
    local result = string_gsub(str, " ", "")
    return result
end

function _M.strip(str)
    if not str or str == "" then return "" end
    local result = string_gsub(str, "^ *", "")
    result = string_gsub(result, "( *)$", "")
    return result
end


function _M.split(str, delimiter)
    if not str or str == "" then return {} end
    if not delimiter or delimiter == "" then return { str } end

    local result = {}
    for match in (str .. delimiter):gmatch("(.-)" .. delimiter) do
        table_insert(result, match)
    end
    return result
end

function _M.startswith(str, substr)
    if str == nil or substr == nil then
        return false
    end
    if string_find(str, substr) ~= 1 then
        return false
    else
        return true
    end
end

function _M.endswith(str, substr)
    if str == nil or substr == nil then
        return false
    end
    local str_reverse = string.reverse(str)
    local substr_reverse = string.reverse(substr)
    if string.find(str_reverse, substr_reverse) ~= 1 then
        return false
    else
        return true
    end
end

return _M

三）编写字符串与json对象编码的工具类

-----------------------json.lua-----------------------------

local cjson = require("cjson.safe")

local _M = {}

function _M.encode(data, empty_table_as_object)
    if not data then return nil end

    if cjson.encode_empty_table_as_object then
        -- empty table default is arrya
        cjson.encode_empty_table_as_object(empty_table_as_object or false)
    end

    if require("ffi").os ~= "Windows" then
        cjson.encode_sparse_array(true)
    end

    return cjson.encode(data)
end


function _M.decode(data)
    if not data then return nil end

    return cjson.decode(data)
end


return _M

四）编写配置文件加载类库

-------------------config_loader.lua---------------------

local json = require("fago.common.json")
local IO = require("fago.common.io")

local _M = {}

function _M.load(config_path)
    config_path = config_path or "/etc/fago/fago.conf"
    local config_contents = IO.read_file(config_path)

    if not config_contents then
        ngx.log(ngx.ERR, "No configuration file at: ", config_path)
        os.exit(1)
    end

    local config = json.decode(config_contents)
    return config, config_path
end

return _M

五）改造主入口fago.lua

-------------------fago.lua------------------------

local utils = require("fago.common.utils")
local config_loader = require("fago.common.config_loader")

local function load_node_plugins(config)
  utils.debug_log("===========load_node_plugins============");
  local plugins = config.plugins --插件列表
  local sorted_plugins = {} --按照优先级的插件集合
  for _, v in ipairs(plugins) do
    local loaded, plugin_handler = utils.load_module_if_exists("fago.plugins." .. v .. ".handler")
    if not loaded then
            utils.warn_log("The following plugin is not installed or has no handler: " .. v)
        else
            utils.debug_log("Loading plugin: " .. v)
            table.insert(sorted_plugins, {
                name = v,
                handler = plugin_handler(), --插件
            })
        end
  end
  --表按照优先级排序
  table.sort(sorted_plugins, function(a, b)
        local priority_a = a.handler.PRIORITY or 0
        local priority_b = b.handler.PRIORITY or 0
        return priority_a > priority_b
    end)
  
  return sorted_plugins
end


local fago = {}

function fago.init(options)
  options = options or {}
  local config
  local status, err = pcall(function()
    --fago的配置文件路径
        local conf_file_path = options.config
    utils.debug_log("Loading fago conf : " .. conf_file_path)
        config = config_loader.load(conf_file_path)
    --加载配置的插件
        loaded_plugins = load_node_plugins(config)
    end)
  
  if not status or err then
        utils.error_log("Startup error: " .. err)
        return ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)  
    end

  ngx.log(ngx.DEBUG, "===========fago.init============");
end

六）更改fago-nginx.conf配置文件

init_by_lua_block {

    local fago = require("fago.fago")

    local config_file = "/usr/local/lua/fago/conf/fago.conf"

    fago.init({
      config = config_file
    })

    context = {
        fago = fago
    }
}

启动nginx，查看nginx日志

cat /usr/local/openresty/nginx/logs/debug.log