fix(clustering): avoid 500 accessing v1 api when inc_sync enabled

fix KAG-5551

kong/init.lua

@@ -884,12 +884,18 @@ function Kong.init_worker()
     kong.cache:invalidate_local(constants.ADMIN_GUI_KCONFIG_CACHE_KEY)
   end
 
-  if process.type() == "privileged agent" and not kong.sync then
-    if kong.clustering then
-      -- full sync cp/dp
+  if kong.clustering then
+    -- full sync dp
+    -- "privileged agent" must be a DP worker
+    if process.type() == "privileged agent" and not kong.sync then
+      kong.clustering:init_worker()
+      -- DP privileged agent skips the rest of the init_worker
+      return
+
+    elseif is_control_plane(kong.configuration) then
+      -- CP needs to support both full and incremental sync
       kong.clustering:init_worker()
     end
-    return
   end
 
   kong.vault.init_worker()
@@ -987,12 +993,6 @@ function Kong.init_worker()
   end
 
   if kong.clustering then
-
-    -- full sync cp/dp
-    if not kong.sync then
-      kong.clustering:init_worker()
-    end
-
     -- rpc and incremental sync
     if kong.rpc and is_http_module then
 

spec/02-integration/09-hybrid_mode/01-sync_spec.lua

@@ -13,7 +13,7 @@ local KEY_AUTH_PLUGIN
 
 
 --- XXX FIXME: enable inc_sync = on
-for _, inc_sync in ipairs { "off"  } do
+for _, inc_sync in ipairs { "on", "off"  } do
 for _, strategy in helpers.each_strategy() do
 
 describe("CP/DP communication #" .. strategy .. " inc_sync=" .. inc_sync, function()
@@ -624,6 +624,12 @@ describe("CP/DP #version check #" .. strategy, function()
   end)
 end)
 
+-- skips the rest of the tests. We will fix them in a follow-up PR
+if inc_sync == "on" then
+  pending("fix this!")
+  return
+end
+
 describe("CP/DP config sync #" .. strategy, function()
   lazy_setup(function()
     helpers.get_db_utils(strategy) -- runs migrations