some doubts about the init operation of orange

Version

v0.7.0

Question one

-- orange/orange/orange.lua
function Orange.init(options)
    options = options or {}
    local store, config
    local status, err = pcall(function()
        local conf_file_path = options.config
        config = config_loader.load(conf_file_path)
        store = require("orange.store.mysql_store")(config.store_mysql)

        loaded_plugins = load_node_plugins(config, store)
        ngx.update_time()
        config.orange_start_at = ngx.now()
    end)

    if not status or err then
        ngx.log(ngx.ERR, "Startup error: " .. err)
        os.exit(1)
    end

    local consul = require("orange.plugins.consul_balancer.consul_balancer")
    consul.set_shared_dict_name("consul_upstream", "consul_upstream_watch")
    Orange.data = {
        store = store,
        config = config,
        consul = consul
    }

    -- init dns_client
    assert(dns_client.init())

    return config, store
end

When i read the source code, i know plugins in the file conf/orange.conf can be loaded according to 'loaded_plugins = load_node_plugins(config, store)'.
But 'local consul = require("orange.plugins.consul_balancer.consul_balancer")' ,why is consul_balancer plugin special? can not loaded by load_node_plugins fucntion if i add consul_balancer configuration to orange/orange.conf?
Are there any special designs here? Hope your answers.

Question two

-- orange/orange/orange.lua
function Orange.init_worker()
    -- 仅在 init_worker 阶段调用，初始化随机因子，仅允许调用一次
    math.randomseed()
    -- 初始化定时器，清理计数器等
    if Orange.data and Orange.data.store and Orange.data.config.store == "mysql" then
            local ok, err = ngx.timer.at(0, function(premature, store, config)
                local available_plugins = config.plugins
                for _, v in ipairs(available_plugins) do
                    local load_success = dao.load_data_by_mysql(store, v)
                    if not load_success then
                        os.exit(1)
                    end

                    if v == "consul_balancer" then
                        for ii,p in ipairs(loaded_plugins) do
                            if v == p.name then
                                p.handler.db_ready()
                            end
                        end
                    end
                end
            end, Orange.data.store, Orange.data.config)

            if not ok then
                ngx.log(ngx.ERR, "failed to create the timer: ", err)
                return os.exit(1)
            end
    end

    for _, plugin in ipairs(loaded_plugins) do
        plugin.handler:init_worker()
    end
end

'plugin.handler:init_worker()', this means loaded_plugins will execute init_worker() function in the handler.lua of the plugins
just uses write plugin as a example, i don't find init_worker() in the rewrite plugin(path:orange/orange/plugins/rewrite/handler.lua).

And i find init_worker() in orange/orange/plugins/base_handler.lua,like this

function BasePlugin:init_worker()
ngx.log(ngx.DEBUG, " executing plugin \"", self._name, "\": init_worker")
end

according to the source code ,init_worker() just for record log ? is there any other purposes？

Question three

-- orange/orange/orange.lua
local function load_node_plugins(config, store)
    ngx.log(ngx.DEBUG, "Discovering used plugins")

    local sorted_plugins = {}
    local plugins = config.plugins

    for _, v in ipairs(plugins) do
        local loaded, plugin_handler = utils.load_module_if_exists("orange.plugins." .. v .. ".handler")
        if not loaded then
            -- ngx.log(ngx.WARN, "The following plugin is not installed or has no handler: " .. v)
            ngx.log(ngx.ERR, "The following plugin is not installed or has no handler: " .. v)
        else
            ngx.log(ngx.DEBUG, "Loading plugin: " .. v)
            table_insert(sorted_plugins, {
                name = v,
                handler = plugin_handler(store),
            })
        end
    end

    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 loaded, plugin_handler = utils.load_module_if_exists("orange.plugins." .. v .. ".handler")' will load handler.lua of the plugin.but kvstore plugin don't have handler.lua file,then i got a error log, kvstore plugin is it possible not to have handler.lua file?
```
2019/07/10 17:17:50 [error] 652903#0: [lua] orange.lua:30: load_node_plugins(): The following plugin is not installed or has no handler: kvstore
```

orlabs / orange

some doubts about the init operation of orange #277

Version

Question one

Question two

Question three