Johan Wikman added a comment - 2024-08-29 08:27 Why do you need to be able to add the same server multiple times? That's almost always a mistake, which is why we prevented it. We made it possible to enable that using a debug option, since that functionality is sometimes useful during development.

Abel Alam added a comment - 2024-08-29 08:46 - edited The ability to add the same server multiple times with different configurations is a critical feature for our deployment. We utilize this capability to assign different priorities and behaviors to the same server depending on the specific port or service being accessed. This configuration ensures that our applications, which connect through different ports, can prioritize certain servers when they are available, thereby reducing the risk of deadlocks and ensuring optimal performance. For example, an application connecting to port 4301 is configured to prioritize server mysql-c1-1-a-m1 when it is available, while an application connecting to port 4302 prioritizes server mysql-c1-2-b-m2. Similarly, a connection through port 4303 would prioritize server mysql-c1-exd-1-c-m3. This targeted priority setup is crucial for our operational needs, as it allows us to control traffic flow and server load based on the specific requirements of each application and service. # by Puppet   # MaxScale documentation: # https: //mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22/   # Global parameters # # Complete list of configuration options: # https: //mariadb.com/kb/en/mariadb-enterprise/mariadb-maxscale-22-mariadb-maxscale-configuration-usage-scenarios/   [maxscale] threads=auto   # Server m1 [mysql-c1- 1 -a-m1] type=server address=mysql-c1- 1 -a.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 1   [mysql-c1- 2 -b-m1] type=server address=mysql-c1- 2 -b.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 2   [mysql-c1-exd- 1 -c-m1] type=server address=mysql-c1-exd- 1 -c.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 3   # Monitor m1   [galera-monitor-m1] type=monitor module=galeramon disable_master_failback= 1 available_when_donor= true servers=mysql-c1- 1 -a-m1,mysql-c1- 2 -b-m1,mysql-c1-exd- 1 -c-m1, use_priority= true monitor_interval= 2000 backend_connect_timeout= 5 backend_write_timeout= 5 backend_read_timeout= 5 user=maxscale passwd=password   # Service m1   [galera-service-m1] type=service router=readconnroute router_options=master servers=mysql-c1- 1 -a-m1,mysql-c1- 2 -b-m1,mysql-c1-exd- 1 -c-m1, log_auth_warnings= true user=maxscale passwd=password   # Listener m1   [galera-listener-m1] type=listener service=galera-service-m1 protocol=MariaDBClient port= 4301   # Server m2 [mysql-c1- 1 -a-m2] type=server address=mysql-c1- 1 -a.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 2   [mysql-c1- 2 -b-m2] type=server address=mysql-c1- 2 -b.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 1   [mysql-c1-exd- 1 -c-m2] type=server address=mysql-c1-exd- 1 -c.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 3   # Monitor m2   [galera-monitor-m2] type=monitor module=galeramon disable_master_failback= 1 available_when_donor= true servers=mysql-c1- 1 -a-m2,mysql-c1- 2 -b-m2,mysql-c1-exd- 1 -c-m2, use_priority= true monitor_interval= 2000 backend_connect_timeout= 5 backend_write_timeout= 5 backend_read_timeout= 5 user=maxscale passwd=password   # Service m2   [galera-service-m2] type=service router=readconnroute router_options=master servers=mysql-c1- 1 -a-m2,mysql-c1- 2 -b-m2,mysql-c1-exd- 1 -c-m2, log_auth_warnings= true user=maxscale passwd=password   # Listener m2   [galera-listener-m2] type=listener service=galera-service-m2 protocol=MariaDBClient port= 4302   # Server m3 [mysql-c1- 1 -a-m3] type=server address=mysql-c1- 1 -a.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 2   [mysql-c1- 2 -b-m3] type=server address=mysql-c1- 2 -b.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 3   [mysql-c1-exd- 1 -c-m3] type=server address=mysql-c1-exd- 1 -c.eu-central- 1 port= 3306 protocol=MariaDBBackend priority= 1   # Monitor m3   [galera-monitor-m3] type=monitor module=galeramon disable_master_failback= 1 available_when_donor= true servers=mysql-c1- 1 -a-m3,mysql-c1- 2 -b-m3,mysql-c1-exd- 1 -c-m3, use_priority= true monitor_interval= 2000 backend_connect_timeout= 5 backend_write_timeout= 5 backend_read_timeout= 5 user=maxscale passwd=password   # Service m3   [galera-service-m3] type=service router=readconnroute router_options=master servers=mysql-c1- 1 -a-m3,mysql-c1- 2 -b-m3,mysql-c1-exd- 1 -c-m3, log_auth_warnings= true user=maxscale passwd=password   # Listener m3   [galera-listener-m3] type=listener service=galera-service-m3 protocol=MariaDBClient port= 4303   # default options   [MaxAdmin-Service] type=service router=cli   [MaxAdmin-Listener] type=listener service=MaxAdmin-Service protocol=maxscaled socket= default

markus makela added a comment - 2024-08-29 09:08 It seems like you need a feature that allows you to control server selection preference based on the listener more than you need to have duplicate servers. I'd imagine that implementing a feature that allows you to do this without duplicating the server sections would be a better solution.

Abel Alam added a comment - 2024-08-29 09:19 We agree that a feature allowing us to control server selection preferences directly within each listener would indeed be an elegant solution. For example, being able to define the priority order for the servers within the listener itself—such as prioritizing mysql-c1-1-a, mysql-c1-2-b, mysql-c1-exd-1-c for port 4301, and mysql-c1-2-b, mysql-c1-1-a, mysql-c1-exd-1-c for port 4302—would streamline the configuration and reduce redundancy. However, we would still be satisfied with the current approach of using duplicate server entries if it could be supported without the need for enabling the debug mode. The flexibility to configure server priorities either through a single server definition or through the existing method with duplicates is essential for our deployment needs. Therefore, either solution would work for us, as long as it's available in a non-debug configuration.

Johan Wikman added a comment - 2024-08-29 09:53 Carverok Your use-case makes sense, but like Markus I'm not sure duplicate server entries is the best way for realizing it. Note that the only thing debug=allow-duplicate-servers does, is to allow duplicate server entries in the configuration. It does not e.g. turn on any kind of debugging mode, but MaxScale functions otherwise exactly like without that flag.

markus makela added a comment - 2024-08-30 04:55 - edited One way to solve the problem of selectively routing to servers would be to implement lazy_connect in readconnroute and then use the namedserverfilter to inject a routing hint than then guides the connection selection in readconnroute. This would have the benefit of falling back to the other servers if the target of the routing hint goes away.