fix(plugin-servers): harden seq number generation

Also, `get_instance_id` uses plugin cache key to fetch instance id.
Kong · Nov 7, 2023 · 9ca82dd · 9ca82dd · khcp-gha-bot · Nov 7, 2023
1 parent 349d36e
commit 9ca82dd
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Showing 3 changed files with 11 additions and 6 deletions.
diff --git a/kong/runloop/plugin_servers/init.lua b/kong/runloop/plugin_servers/init.lua
@@ -213,7 +213,7 @@ function get_instance_id(plugin_name, conf)
 
   if instance_info
     and instance_info.id
-    and instance_info.seq == conf.__seq__
+    and instance_info.conf and instance_info.conf.__key__ == key
   then
     -- exact match, return it
     return instance_info.id
@@ -224,7 +224,6 @@ function get_instance_id(plugin_name, conf)
     -- we're the first, put something to claim
     instance_info          = {
       conf = conf,
-      seq = conf.__seq__,
     }
     running_instances[key] = instance_info
   else
@@ -247,7 +246,6 @@ function get_instance_id(plugin_name, conf)
   instance_info.id = new_instance_info.id
   instance_info.plugin_name = plugin_name
   instance_info.conf = new_instance_info.conf
-  instance_info.seq = new_instance_info.seq
   instance_info.Config = new_instance_info.Config
   instance_info.rpc = new_instance_info.rpc
 

diff --git a/kong/runloop/plugin_servers/pb_rpc.lua b/kong/runloop/plugin_servers/pb_rpc.lua
@@ -371,6 +371,9 @@ function Rpc:call_start_instance(plugin_name, conf)
     return nil, err
   end
 
+  kong.log.debug("started plugin server: seq ", conf.__seq__, ", worker ", ngx.worker.id(), ", instance id ",
+    status.instance_status.instance_id)
+
   return {
     id = status.instance_status.instance_id,
     conf = conf,

diff --git a/kong/runloop/plugins_iterator.lua b/kong/runloop/plugins_iterator.lua
@@ -61,7 +61,6 @@ do
 end
 
 
-local NEXT_SEQ = 0
 local PLUGINS_NS = "plugins." .. subsystem
 local ENABLED_PLUGINS
 local LOADED_PLUGINS
@@ -170,8 +169,13 @@ local function get_plugin_config(plugin, name, ws_id)
   -- TODO: deprecate usage of __key__ as id of plugin
   if not cfg.__key__ then
     cfg.__key__ = key
-    cfg.__seq__ = NEXT_SEQ
-    NEXT_SEQ = NEXT_SEQ + 1
+    -- generate a unique sequence across workers
+    -- with a seq 0, plugin server generates an unused random instance id
+    local next_seq, err = ngx.shared.kong:incr("plugins_iterator:__seq__", 1, 0, 0)
+    if err then
+      next_seq = 0
+    end
+    cfg.__seq__ = next_seq
   end
 
   return cfg