check get_latest_version()

kong/clustering/services/sync/hooks.lua

@@ -53,7 +53,12 @@ end
 
 
 function _M:notify_all_nodes()
-  local latest_version = self.strategy:get_latest_version()
+  local latest_version, err = self.strategy:get_latest_version()
+  if not latest_version then
+    ngx_log(ngx_ERR, "can not get the latest version: ", err)
+    return
+  end
+
   local msg = { default = { new_version = latest_version, }, }
 
   for _, node in ipairs(get_all_nodes_with_sync_cap()) do

kong/clustering/services/sync/rpc.lua

@@ -86,9 +86,14 @@ function _M:init_cp(manager)
       ngx_log(ngx_ERR, "unable to update clustering data plane status: ", err)
     end
 
+    local latest_version, err = self.strategy:get_latest_version()
+    if not latest_version then
+      return nil, err
+    end
+
     -- is the node empty? If so, just do a full sync to bring it up to date faster
     if default_namespace_version == 0 or
-       self.strategy:get_latest_version() - default_namespace_version > FULL_SYNC_THRESHOLD
+       latest_version - default_namespace_version > FULL_SYNC_THRESHOLD
     then
       -- we need to full sync because holes are found
 

kong/clustering/services/sync/strategies/postgres.lua

@@ -91,7 +91,13 @@ end
 
 function _M:get_latest_version()
   local sql = "SELECT MAX(version) AS max_version FROM clustering_sync_version"
-  return self.connector:query(sql)[1].max_version
+
+  local res, err = self.connector:query(sql)
+  if not res then
+    return nil, err
+  end
+
+  return res[1].max_version
 end