Hi,

Thank you for testing MaxScale and reporting your findings. We haven't seen the behavior you described and it is certainly not expected. One possibility I can think of is that for some reason, a TLS connection is created between the monitor and the Galera when a normal one should be used. Unless the servers are configured to use TLS, the monitor should create normal, plain connections.

I think you can decrypt the packets with Wireshark as long as you have the private key and the certificate. This might be a helpful link in determining what the encrypted packet was: https://wiki.wireshark.org/SSL

As this is not expected behavior, I would like to ask you to file a bug report on the MariaDB Jira under the MaxScale project. Hopefully we'll get to the bottom of this soon.

Markus

On 12/10/17 19:39, Pak Chan wrote:

Hi,

I'm (still) testing MaxScale, set up to connect only to the master node, on Ubuntu 16.04 fronting a Galera cluster. The cluster comprises of 2 MariaDB 10.1 instances on different servers, with a Galera Arbitrator instance running on the MaxScale server. I'm testing this using the MariaDB client (mysql) from a fourth machine.

My test scenario is to see what the client experiences if I stop and restart a MariaDB node part-way through a transaction. I start with the "slave" node, to give me a baseline for comparison, before doing it with the master node. However, the baseline case gives me different results, depending on whether the MySQL client is connecting via TLS or not.

If I connect to MaxScale via TLS, the connection disappears when the "slave" node comes back (but not when it goes down). Watching it via a network packet trace, I can see that, just after the slave comes back up, MaxScale sends the client an encrypted packet to the mysql client, then sends a MySQL Quit command to the master node before disconnecting. The syslog contains the line "[galeramon] There are no cluster members".

If I connect to MaxScale without TLS, the connection remains stable regardless of the number of times the slave node goes down and up, and the "galeramon" line doesn't appear in the syslog. (I discovered this when I disabled the TLS in order to see what the encrypted packet being sent to the client was...I still don't know what it is!)

Has anyone else come across this behaviour?

MaxScale is configured as follows (the commented-out configuration is uncommented when connecting via TLS):

[dbnode1]

type=server

address=172.16.1.22

port=3306

protocol=MySQLBackend

priority=1

[dbnode2]

type=server

address=172.16.1.23

port=3306

protocol=MySQLBackend

priority=2

[Galera Monitor]

type=monitor

module=galeramon

servers=dbnode1,dbnode2

user=galeramon

passwd=galeramon

monitor_interval=1000

available_when_donor=true

use_priority=true

[Galera Service]

type=service

router=readrouteconn

router_options=master

servers=dbnode1,dbnode2

user=galeramon

passwd=galeramon

[MaxAdmin Service]

type=service

router=cli

[Galera Listener]

type=listener

service=Galera Service

protocol=MySQLClient

port=3306

#ssl=required

#ssl_version=TLSv12

#ssl_cert=/etc/mysql/ssl/server-cert.pem

#ssl_key=/etc/mysql/ssl/server-key.pem

#ssl_ca_cert=/etc/mysql/ssl/ca-cert.pem

#ssl_cert_verify_depth=1

 

[MaxAdmin Listener]

type=listener

service=MaxAdmin Service

protocol=maxscaled

socket=default

PC

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-- 
Markus Mäkelä, Software Engineer
MariaDB Corporation
t: +358 40 7740484 | Skype: markus.j.makela 

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