feature: mini example to load plugin.

conf/config.yaml

@@ -5,3 +5,4 @@ etcd:
 
 plugins:
   - example_plugin
+  - not_exist_plugin

lua/apimeta/core/config.lua

@@ -1,16 +1,15 @@
 -- Copyright (C) Yuansheng Wang
 
 local ngx = ngx
-local pcall = pcall
 local yaml = require("apimeta.core.yaml")
 local io_open = io.open
-
+local type = type
 local config_path = ngx.config.prefix() .. "conf/config.yaml"
 
 local _M = {}
 
 local function read_file(path)
-    local file = io_open(path, "rb")   -- r read mode and b binary mode
+    local file = io_open(path, "rb")   -- read and binary mode
     if not file then
         return nil
     end

lua/apimeta/plugin.lua

@@ -1,6 +1,14 @@
+local require = require
+local config = require("apimeta.core.config")
 local typeof = require("apimeta.core.typeof")
 local log = require("apimeta.core.log")
+local new_tab = require("table.new")
+local insert_tab = table.insert
+local sort_tab = table.sort
 local tostring = tostring
+local pcall = pcall
+local ipairs = ipairs
+local pairs = pairs
 
 
 local _M = {
@@ -19,5 +27,44 @@ function _M.check_args(args, scheme)
     return true
 end
 
+local function sort_plugin(l, r)
+    return l.priority > r.priority
+end
+
+function _M.load()
+    local plugin_names = config.read().plugins
+    if not plugin_names then
+        return nil, "failed to read plugin list form local file"
+    end
+
+    local plugins = new_tab(#plugin_names, 0)
+    for _, name in ipairs(plugin_names) do
+        local ok, plugin = pcall(require, "apimeta.plugins." .. name)
+        if not ok then
+            log.error("failed to load plugin ", name, " err: ", plugin)
+
+        elseif not plugin.priority then
+            log.error("invalid plugin", name, ", missing field: priority")
+
+        elseif not plugin.check_args then
+            log.error("invalid plugin", name, ", missing method: check_args")
+
+        elseif not plugin.version then
+            log.error("invalid plugin", name, ", missing field: version")
+
+        else
+            plugin.name = name
+            insert_tab(plugins, plugin)
+        end
+    end
+
+    -- sort by plugin's priority
+    if #plugins > 1 then
+        sort_tab(plugins, sort_plugin)
+    end
+
+    return plugins
+end
+
 
 return _M

lua/apimeta/plugins/example_plugin.lua

@@ -1,14 +1,19 @@
 local plugin = require("apimeta.plugin")
 
 
+-- TODO: need a more powerful way to define the schema
 local args_schema = {
-    i = "int",          -- value list: apimeta.core.typeof#92
+    i = "int",              -- value list: apimeta.core.typeof#92
     s = "string",
     t = "table",
 }
 
 
-local _M = {version = 0.1}
+local _M = {
+    version = 0.1,
+    priority = 1000,        -- TODO: add a type field, may be a good idea
+    name = "example_plugin",
+}
 
 
 function _M.check_args(config)

t/example-plugin.t

@@ -1,15 +1,14 @@
 use t::APIMeta 'no_plan';
 
-repeat_each(1);
+repeat_each(2);
 no_long_string();
-no_shuffle();
 log_level('info');
 
 run_tests;
 
 __DATA__
 
-=== TEST 1: sanity
+=== TEST 1: check arguments
 --- config
     location /t {
         content_by_lua_block {
@@ -44,3 +43,31 @@ failed to check args: args.i expect int value but got: [nil]
 failed to check args: args.s expect string value but got: [3]
 failed to check args: args.t expect table value but got: []
 done
+
+
+
+=== TEST 2: load plugins
+--- config
+    location /t {
+        content_by_lua_block {
+            local plugins, err = require("apimeta.plugin").load()
+            if not plugins then
+                ngx.say("failed to load plugins: ", err)
+            end
+
+            local encode_json = require "cjson.safe" .encode
+            for _, plugin in ipairs(plugins) do
+                ngx.say("plugin name: ", plugin.name,
+                        " priority: ", plugin.priority)
+
+                plugin.rewrite()
+            end
+        }
+    }
+--- request
+GET /t
+--- response_body
+plugin name: example_plugin priority: 1000
+--- error_log
+failed to load plugin not_exist_plugin err: module 'apimeta.plugins.not_exist_plugin' not found
+rewrite(): plugin rewrite phase

t/sanity.t

@@ -1,8 +1,7 @@
 use t::APIMeta 'no_plan';
 
-repeat_each(1);
+repeat_each(2);
 no_long_string();
-no_shuffle();
 log_level('info');
 
 run_tests();

t/yaml-config.t

@@ -1,8 +1,7 @@
 use t::APIMeta 'no_plan';
 
-repeat_each(1);
+repeat_each(2);
 no_long_string();
-no_shuffle();
 log_level('info');
 
 run_tests;
@@ -26,4 +25,4 @@ GET /t
 --- response_body
 etcd host: http://127.0.0.1:2379
 etcd prefix: /v2/keys
-plugins: ["example_plugin"]
+plugins: ["example_plugin","not_exist_plugin"]