Move require_serializer into v3

* Fix #126
* cause to conform to v3.md

Signed-off-by: u5surf <u5.horie@gmail.com>

Author: u5surf

lib/resty/etcd.lua

@@ -6,17 +6,6 @@ local pcall   = pcall
 local _M = {version = 0.9}
 
 
-local function require_serializer(serializer_name)
-    if serializer_name then
-        local ok, module = pcall(require, "resty.etcd.serializers." .. serializer_name)
-        if ok then
-            return module
-        end
-    end
-
-    return require("resty.etcd.serializers.json")
-end
-
 function _M.new(opts)
     opts = opts or {}
     if not typeof.table(opts) then
@@ -33,7 +22,7 @@ function _M.new(opts)
     opts.ttl  = opts.ttl or -1
 
     local serializer_name = typeof.string(opts.serializer) and opts.serializer
-    opts.serializer = require_serializer(serializer_name)
+    opts.serializer = serializer_name
     opts.api_prefix = "/v3"
 
     return etcdv3.new(opts)

lib/resty/etcd/v3.lua

@@ -265,6 +265,17 @@ local function serialize_and_encode_base64(serialize_fn, data)
     return encode_base64(data)
 end
 
+local function require_serializer(serializer_name)
+    if serializer_name then
+        local ok, module = pcall(require, "resty.etcd.serializers." .. serializer_name)
+        if ok then
+            return module
+        end
+    end
+
+    return require("resty.etcd.serializers.json")
+end
+
 
 function _M.new(opts)
     local timeout    = opts.timeout
@@ -278,7 +289,7 @@ function _M.new(opts)
     if ssl_verify == nil then
         ssl_verify = true
     end
-    local serializer = opts.serializer
+    local serializer = require_serializer(opts.serializer)
     local extra_headers = opts.extra_headers
     local sni        = opts.sni
     local unix_socket_proxy = opts.unix_socket_proxy