MySQL Bugs: #41866: Agent having SUPER privileges can lock you out of mysqld

Bug #41866	Agent having SUPER privileges can lock you out of mysqld
Submitted:	5 Jan 2009 13:49	Modified:	9 Jan 2015 10:07
Reporter:	Diego Medina	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Agent	Severity:	S2 (Serious)
Version:	2.0.1.7125	OS:	Any
Assigned to:	Assigned Account	CPU Architecture:	Any

Description:
The agent needs the "SUPER" privilege for some operations, and it stays connected to the monitored mysqld while running.

MySQL server has an option "max_connections" that is actually max_connections + 1 (super privileged user)

This is so that when you reach max_connections, you can log in into the server using your root user and either kill some connections or see what is going on.

But as the agent uses the super privilege, you cannot login into the server unless you disconnect the agent or try something else.

How to repeat:
1- Install and start the agent and service manager
2- Set the max_connections=2 on your monitored mysqld
3- start your monitored mysqld
4- Using the mysql command line client, start another connection to the mysqld server
5- Try to start again a new connection, you would get an error and you will not be able to login into the mysql server, even using the root user.

Jan Kneschke writes: 
Instead of just documenting it, I move it to 3.0 Consider.

[16:53]  <jan> Leith, MC: should I assign this bug to MC https://repoman.mysql.com/jira/browse/EM-309 ?
[16:54]  <Leith> jan: no - put it on 3.0 consider, I have some thoughts around it
[16:54]  <Leith> the 3.0 agent will allow sending statements on different connections
[16:55]  <Leith> one of the things we should think about is having a separate login that just uses SUPER for specific commands