MariaDB MaxScale Offline Installation for CentOS 8

For offline installation, a number of things have to be configured in the first place:

• SELinux is disabled, or set permissive mode.
• A mysql client is optional but recommended to test out the client connectivity from MaxScale server. This requires local repository to be configured correctly.

In this example, we are going to deploy our MaxScale with the following configuration:

Installation & Configuration

1. Download the MaxScale installer from the MariaDB download page. Choose the latest GA version and CentOS 8 as the operating system. In this example, the link that we got was:

   https://dlm.mariadb.com/1092012/MaxScale/2.5.1/centos/8/x86_64/maxscale-2.5.1-1.centos.8.x86_64.rpm 

   Transfer the downloaded package into the MaxScale server.

2. Install MariaDB MaxScale using yum:

   yum localinstall maxscale-2.5.1-1.centos.8.x86_64.rpm 

3. Create a monitoring user that will be used by MaxScale on one of the MariaDB servers:

   CREATE USER `maxscale_monitor`@`192.168.10.220` IDENTIFIED BY 'Th7sdJLKp2';
   GRANT SELECT ON mysql.* TO `maxscale_monitor`@`192.168.10.220`;
   GRANT SHOW DATABASES ON *.* TO `maxscale_monitor`@`192.168.10.220`; 

   Where, 192.168.10.220 is the IP address of our MaxScale server.

4. It is unsafe to store the monitoring user password inside the MaxScale configuration file in plain text. Therefore, we have to use encryption. MaxScale provide a tool to generate encrypted secrets called maxkeys and maxpasswd. Firstly, generate a key:

   $ maxkeys
   Generating .secrets file in /var/lib/maxscale.

5. Then, generate the encrypted value of our password “Th7sdJLKp2w”:

   $ maxpasswd Th7sdJLKp2w
   D91DB5813F7C815B351CCF7D7F1ED6DB 

6. Now we can use the generated value above in our MaxScale configuration at /etc/maxscale.cnf:

   [maxscale]
   threads=auto
   
   # Server definitions
   #
   # Set the address of the server to the network
   # address of a MariaDB server.
   #
   
   [mariadbgalera1]
   type=server
   address=192.168.10.201
   port=3306
   protocol=MariaDBBackend
   priority=1
   
   [mariadbgalera2]
   type=server
   address=192.168.10.202
   port=3306
   protocol=MariaDBBackend
   priority=2
   
   [mariadbgalera3]
   type=server
   address=192.168.10.203
   port=3306
   protocol=MariaDBBackend
   priority=3
   
   # Monitor for the servers
   #
   # This will keep MaxScale aware of the state of the servers.
   # MariaDB Monitor documentation:
   # https://mariadb.com/kb/en/mariadb-maxscale-24-mariadb-monitor/
   
   [MariaDB-Monitor]
   type=monitor
   module=galeramon
   servers=mariadbgalera1,mariadbgalera2,mariadbgalera3
   user=maxscale_monitor
   password=D91DB5813F7C815B351CCF7D7F1ED6DB
   monitor_interval=2000
   available_when_donor=true
   
   # Service definitions
   #
   # Service Definition for a read-only service and
   # a read/write splitting service.
   #
   
   [Read-Write-Service]
   type=service
   router=readwritesplit
   servers=mariadbgalera1,mariadbgalera2,mariadbgalera3
   user=maxscale_monitor
   password=D91DB5813F7C815B351CCF7D7F1ED6DB
   
   [Round-Robin-Service]
   type=service
   router=readconnroute
   servers=mariadbgalera1,mariadbgalera2,mariadbgalera3
   user=maxscale_monitor
   password=D91DB5813F7C815B351CCF7D7F1ED6DB
   router_options=slave
   
   # Listener definitions for the services
   #
   # These listeners represent the ports the
   # services will listen on.
   #
   
   [Read-Write-Listener]
   type=listener
   service=Read-Write-Service
   protocol=MariaDBClient
   port=3306
   address=0.0.0.0
   
   [Round-Robin-Listener]
   type=listener
   service=Round-Robin-Service
   protocol=MariaDBClient
   port=3307
   address=0.0.0.0 

7. Start and enable the MaxScale service on boot:

   systemctl start maxscale
   systemctl enable maxscale 

Verification

We can verify if MaxScale is running correctly by using:

$ systemctl status maxscale
● maxscale.service - MariaDB MaxScale Database Proxy
   Loaded: loaded (/usr/lib/systemd/system/maxscale.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2020-07-30 03:33:54 UTC; 2min 35s ago
 Main PID: 5112 (maxscale)
   CGroup: /system.slice/maxscale.service
           └─5112 /usr/bin/maxscale
Jul 30 03:33:54 mxb1.local maxscale[5112]: [MariaDBAuth] [Round-Robin-Service] Loaded 13 MySQL users for listener 'Round-Robin-Listener' from server 'mariadbgalera1' with c... 0x92ff8486.
Jul 30 03:33:54 mxb1.local maxscale[5112]: Listening for connections at [0.0.0.0]:3307
Jul 30 03:33:54 mxb1.local maxscale[5112]: Service 'Round-Robin-Service' started (2/3)
Jul 30 03:33:54 mxb1.local maxscale[5112]: Removing stale journal file for monitor 'MariaDB-Monitor'.
Jul 30 03:33:54 mxb1.local systemd[1]: Started MariaDB MaxScale Database Proxy.
Jul 30 03:33:54 mxb1.local maxscale[5112]: Server changed state: mariadbgalera1[192.168.10.201:3306]: new_slave. [Running] -> [Slave, Synced, Running]
Jul 30 03:33:54 mxb1.local maxscale[5112]: Server changed state: mariadbgalera2[192.168.10.202:3306]: new_slave. [Running] -> [Slave, Synced, Running]
Jul 30 03:33:54 mxb1.local maxscale[5112]: Server changed state: mariadbgalera3[192.168.10.203:3306]: new_master. [Running] -> [Master, Synced, Running] 

Or,

$ netstat -tulpn | grep maxscale
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      5112/maxscale
tcp        0      0 0.0.0.0:3307            0.0.0.0:*               LISTEN      5112/maxscale
tcp        0      0 127.0.0.1:8989          0.0.0.0:*               LISTEN      5112/maxscale 

Take note at the ports that are configured for MaxScale and make sure they are listening correctly.

Furthermore, you can observe the MaxScale log at:

tail -f /var/log/maxscale/maxscale.log