fix(pluginservers): workers invalidate instances

Ensure that if a pluginserver is restarted all workers invalidate their
running instances.

Fixes FTI-5238

kong/runloop/plugin_servers/init.lua

@@ -200,7 +200,7 @@ function get_instance_id(plugin_name, conf)
     -- some other thread is already starting an instance
     -- prevent busy-waiting
     ngx_sleep(SLEEP_STEP)
-  
+
     -- to prevent a potential dead loop when someone failed to release the ID
     wait_count = wait_count + 1
     if wait_count > MAX_WAIT_STEPS then
@@ -386,6 +386,7 @@ end
 
 
 function plugin_servers.start()
+  -- only worker 0 managers the plugin server
   if worker_id() == 0 then
     local pluginserver_timer = proc_mgmt.pluginserver_timer
 
@@ -396,13 +397,20 @@ function plugin_servers.start()
     end
   end
 
+  -- workers != 0 still need to get plugin servers definitions
+  --
   local connection_check_timer = proc_mgmt.connection_check_timer
 
   for _, server_def in ipairs(proc_mgmt.get_server_defs()) do
     if server_def.start_command then
       native_timer_at(0, connection_check_timer, server_def)
     end
   end
+
+  -- in case plugin server restarts, all workers need to update their defs
+  kong.worker_events.register(function (data)
+    reset_instance(data.plugin_name, data.conf)
+  end, "plugin_server", "reset_instances")
 end
 
 function plugin_servers.stop()

kong/runloop/plugin_servers/pb_rpc.lua

@@ -400,15 +400,23 @@ function Rpc:handle_event(plugin_name, conf, phase)
   end
 
   if not res or res == "" then
-    if err == "not ready" then
-      self.reset_instance(plugin_name, conf)
-      return handle_not_ready(plugin_name)
-    end
-    if err and (str_find(err:lower(), "no plugin instance", 1, true)
-      or str_find(err:lower(), "closed", 1, true)) then
-      kong.log.warn(err)
-      self.reset_instance(plugin_name, conf)
-      return self:handle_event(plugin_name, conf, phase)
+    if err then
+      local ok, err = kong.worker_events.post("plugin_server", "reset_instances",
+      { plugin_name = plugin_name, conf = conf })
+      if not ok then
+        kong.log.err("failed to post plugin_server reset_instances event: ", err)
+      end
+
+      if err == "not ready" then
+        self.reset_instance(plugin_name, conf)
+        return handle_not_ready(plugin_name)
+      end
+      if err and (str_find(err:lower(), "no plugin instance", 1, true)
+        or str_find(err:lower(), "closed", 1, true)) then
+        kong.log.warn(err)
+        self.reset_instance(plugin_name, conf)
+        return self:handle_event(plugin_name, conf, phase)
+      end
     end
     kong.log.err(err)
   end