fix(*): lazily initialize structures to avoid c-boundary errors on re…

…quire

### Summary

Moves the code that was previously running on `module` level to `initialize` function
that are lazily called when needed. This is to avoid the `yield accross C-boundary`
errors during `require`.

src/resty/aws/credentials/CredentialProviderChain.lua

@@ -11,7 +11,10 @@ CredentialProviderChain.__index = CredentialProviderChain
 local aws_config = require("resty.aws.config")
 
 
-CredentialProviderChain.defaultProviders = {} do
+CredentialProviderChain.defaultProviders = {}
+
+
+local function initialize()
   -- while not everything is implemented this will load what we do have without
   -- failing on what is missing. Will auto pick up newly added classes afterwards.
   local function add_if_exists(name, opts)
@@ -41,6 +44,8 @@ CredentialProviderChain.defaultProviders = {} do
   else
     add_if_exists("EC2MetadataCredentials")
   end
+
+  initialize = nil
 end
 
 --- Constructor, inherits from `Credentials`.
@@ -65,6 +70,11 @@ end
 -- @param opt options table, additional fields to the `Credentials` class:
 -- @param opt.providers array of `Credentials` objects or functions (functions must return a `Credentials` object)
 function CredentialProviderChain:new(opts)
+  if initialize then
+    initialize()
+    initialize = nil
+  end
+
   local self = Super:new(opts)  -- override 'self' to be the new object/class
   setmetatable(self, CredentialProviderChain)
 

src/resty/aws/credentials/RemoteCredentials.lua

@@ -15,9 +15,11 @@ local http = require "resty.luasocket.http"
 local json = require "cjson"
 
 
-local FullUri do
-  -- construct the URL
+local FullUri
+
 
+local function initialize()
+  -- construct the URL
   local function makeset(t)
     for i = 1, #t do
       t[t[i]] = true
@@ -73,8 +75,9 @@ local FullUri do
     FullUri.port = FullUri.port or
                     ({ http = 80, https = 443 })[FullUri.scheme]
   end
-end
 
+  initialize = nil
+end
 
 
 -- Create class
@@ -96,6 +99,10 @@ end
 -- updates credentials.
 -- @return success, or nil+err
 function RemoteCredentials:refresh()
+  if initialize then
+    initialize()
+  end
+
   if not FullUri then
     return nil, "No URI environment variables found for RemoteCredentials"
   end