MariaDBクラスターにMaxCtrlを使用したMaxScale基本管理

サービス（ルーター）を作成するには、MariaDBサーバーのバックエンドに監視ユーザーを作成する必要があります。通常、モニターモジュールに定義したものと同じモニタリングユーザーを使用します。 Galera Clusterの場合、監視ユーザーが存在しない場合は、次の権限を持つノードの1つに作成するだけです。

MariaDB> CREATE USER [email protected]'192.168.0.220' IDENTIFIED BY 'MaXSc4LeP4ss';
MariaDB> GRANT SELECT ON mysql.* TO 'maxscale_monitor'@'192.168.0.220';
MariaDB> GRANT SHOW DATABASES ON *.* TO 'maxscale_monitor'@'192.168.0.220';

ここで、192.168.0.220はMaxScaleホストのIPアドレスです。

次に、サービスの名前、ルーティングタイプ、およびバックエンドサーバーに接続するMaxScaleの監視ユーザーを指定します。

 maxctrl: create service Round-Robin-Service readconnroute user=maxscale_monitor password=******
OK

また、サービスの作成時に追加のパラメーターを指定できます。この例では、「マスター」ノードをMariaDBガレラクラスターのラウンドロビンバランシングセットに含める必要があります。

 maxctrl: create service Round-Robin-Service readconnroute user=maxscale_monitor password=****** router_options=master,slave
OK

「showservice」コマンドを使用して、サポートされているパラメーターを確認します。ラウンドロビンルーターの場合、リストは次のとおりです。

  maxctrl: show service Round-Robin-Service
...
│ Parameters          │ {                                          │
│                     │     "router_options": null,                │
│                     │     "user": "maxscale_monitor",            │
│                     │     "password": "*****",                   │
│                     │     "passwd": null,                        │
│                     │     "enable_root_user": false,             │
│                     │     "max_retry_interval": 3600,            │
│                     │     "max_connections": 0,                  │
│                     │     "connection_timeout": 0,               │
│                     │     "auth_all_servers": false,             │
│                     │     "strip_db_esc": true,                  │
│                     │     "localhost_match_wildcard_host": true, │
│                     │     "version_string": null,                │
│                     │     "weightby": null,                      │
│                     │     "log_auth_warnings": true,             │
│                     │     "retry_on_failure": true,              │
│                     │     "session_track_trx_state": false,      │
│                     │     "retain_last_statements": -1,          │
│                     │     "session_trace": 0

読み取り/書き込み分割ルーターの場合、サポートされるパラメーターは次のとおりです。

  maxctrl: show service Read-Write-Service
...
│ Parameters          │ {                                                           │
│                     │     "router_options": null,                                 │
│                     │     "user": "maxscale_monitor",                             │
│                     │     "password": "*****",                                    │
│                     │     "passwd": null,                                         │
│                     │     "enable_root_user": false,                              │
│                     │     "max_retry_interval": 3600,                             │
│                     │     "max_connections": 0,                                   │
│                     │     "connection_timeout": 0,                                │
│                     │     "auth_all_servers": false,                              │
│                     │     "strip_db_esc": true,                                   │
│                     │     "localhost_match_wildcard_host": true,                  │
│                     │     "version_string": null,                                 │
│                     │     "weightby": null,                                       │
│                     │     "log_auth_warnings": true,                              │
│                     │     "retry_on_failure": true,                               │
│                     │     "session_track_trx_state": false,                       │
│                     │     "retain_last_statements": -1,                           │
│                     │     "session_trace": 0,                                     │
│                     │     "use_sql_variables_in": "all",                          │
│                     │     "slave_selection_criteria": "LEAST_CURRENT_OPERATIONS", │
│                     │     "master_failure_mode": "fail_instantly",                │
│                     │     "max_slave_replication_lag": -1,                        │
│                     │     "max_slave_connections": "255",                         │
│                     │     "retry_failed_reads": true,                             │
│                     │     "prune_sescmd_history": false,                          │
│                     │     "disable_sescmd_history": false,                        │
│                     │     "max_sescmd_history": 50,                               │
│                     │     "strict_multi_stmt": false,                             │
│                     │     "strict_sp_calls": false,                               │
│                     │     "master_accept_reads": false,                           │
│                     │     "connection_keepalive": 300,                            │
│                     │     "causal_reads": false,                                  │
│                     │     "causal_reads_timeout": "10",                           │
│                     │     "master_reconnection": false,                           │
│                     │     "delayed_retry": false,                                 │
│                     │     "delayed_retry_timeout": 10,                            │
│                     │     "transaction_replay": false,                            │
│                     │     "transaction_replay_max_size": "1Mi",                   │
│                     │     "optimistic_trx": false                                 │
│                     │ }

List/Show Services
 

To list out all created services (routers), use the "list services" command:

 maxctrl: list services
┌─────────────────────┬────────────────┬─────────────┬───────────────────┬────────────────────────────────────────────────┐
│ Service             │ Router         │ Connections │ Total Connections │ Servers                                        │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Read-Write-Service  │ readwritesplit │ 1           │ 1                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Round-Robin-Service │ readconnroute  │ 1           │ 1                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Binlog-Repl-Service │ binlogrouter   │ 1           │ 1                 │                                                │
└─────────────────────┴────────────────┴─────────────┴───────────────────┴────────────────────────────────────────────────┘

In the above examples, we have created 3 services, with 3 different routers. However, the Binlog-Repl-Service for our binlog server is not linked with any servers yet.

To show all services in details:

 maxctrl: show services

Or if you want to show a particular service:

 maxctrl: show service Round-Robin-Service

Stop/Start Services

Stopping a service will prevent all the listeners for that service from accepting new connections. Existing connections will still be handled normally until they are closed. To stop and start all services, use the "stop services":

 maxctrl: stop services
 maxctrl: show services
 maxctrl: start services
 maxctrl: show services

Or we can use the "stop service" to stop only one particular service:

 maxctrl: stop services Round-Robin-Service

Delete a Service

In order to delete a service, one has to remove all servers and destroy the listeners associated with the service first. For example, consider the following services in MaxScale:

 maxctrl: list services
┌─────────────────────┬────────────────┬─────────────┬───────────────────┬────────────────────────────────────────────────┐
│ Service             │ Router         │ Connections │ Total Connections │ Servers                                        │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Read-Write-Service  │ readwritesplit │ 1           │ 1                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Round-Robin-Service │ readconnroute  │ 1           │ 1                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Replication-Service │ binlogrouter   │ 1           │ 1                 │                                                │
└─────────────────────┴────────────────┴─────────────┴───────────────────┴────────────────────────────────────────────────┘

Let's remove Round-Robin-Service from the setup. Remove all servers from this particular service:

 maxctrl: unlink service Round-Robin-Service mariadbgalera1 mariadbgalera2 mariadbgalera3
OK

Our services are now looking like this:

 maxctrl: list services
┌─────────────────────┬────────────────┬─────────────┬───────────────────┬────────────────────────────────────────────────┐
│ Service             │ Router         │ Connections │ Total Connections │ Servers                                        │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Read-Write-Service  │ readwritesplit │ 1           │ 1                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Round-Robin-Service │ readconnroute  │ 1           │ 1                 │                                                │
├─────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Replication-Service │ binlogrouter   │ 1           │ 1                 │                                                │
└─────────────────────┴────────────────┴─────────────┴───────────────────┴────────────────────────────────────────────────┘

If the service is tied with a listener, we have to remove it as well. Use "list listeners" and specify the service name to look for it:

 maxctrl: list listeners Round-Robin-Service
┌──────────────────────┬──────┬─────────┬─────────┐
│ Name                 │ Port │ Host    │ State   │
├──────────────────────┼──────┼─────────┼─────────┤
│ Round-Robin-Listener │ 3307 │ 0.0.0.0 │ Running │
└──────────────────────┴──────┴─────────┴─────────┘

And then remove the listener:

 maxctrl: destroy listener Round-Robin-Service Round-Robin-Listener
OK

Finally, we can remove the service:

 maxctrl: destroy service Round-Robin-Service
OK

Modify Service's Parameter

Similar to the other object, one can modify a service parameter by using the "alter service" command:

 maxctrl: alter service Read-Write-Service master_accept_reads true
OK

Some routers support runtime configuration changes to all parameters. Currently all readconnroute, readwritesplit and schemarouter parameters can be changed at runtime. In addition to module specific parameters, the following list of common service parameters can be altered at runtime:

• user
• passwd
• enable_root_user
• max_connections
• connection_timeout
• auth_all_servers
• optimize_wildcard
• strip_db_esc
• localhost_match_wildcard_host
• max_slave_connections
• max_slave_replication_lag
• retain_last_statements

Note that alter command effect is immediate and the parameter's value in the runtime will be modified as well as the value in its individual MaxScale configuration file inside /var/lib/maxscale/maxscale.cnf.d/ for persistence across restart.

Add/Remove Servers into Service

After creating a service, we can use the link command to add our servers into the service. Use the server's name as created under Create Servers section:

 maxctrl: link service Round-Robin-Service mariadbgalera1 mariadbgalera2 mariadbgalera3
OK

Similarly, to remove a server from the service, just use "unlink service" command:

 maxctrl: unlink service Round-Robin-Service mariadbgalera3
OK

We can only remove one server from a service at a time, so repeat it for other nodes to delete them. Verify with "list services" or "show services" command.

Listener Management

List Listeners

To list all listeners, we need to know the service name in advanced:

maxctrl: list services
┌──────────────────────┬────────────────┬─────────────┬───────────────────┬────────────────────────────────────────────────┐
│ Service              │ Router         │ Connections │ Total Connections │ Servers                                        │
├──────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Read-Write-Service   │ readwritesplit │ 0           │ 0                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├──────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤
│ Round-Robin-Service  │ readconnroute  │ 0           │ 0                 │ mariadbgalera1, mariadbgalera2, mariadbgalera3 │
├──────────────────────┼────────────────┼─────────────┼───────────────────┼────────────────────────────────────────────────┤

In the above example, we have two services, Read-Write-Service and Round-Robin-Service. Then, we can list out the listener for that particular service. For Read-Write-Service:

 maxctrl: list listeners Read-Write-Service
┌─────────────────────┬──────┬─────────┬─────────┐
│ Name                │ Port │ Host    │ State   │
├─────────────────────┼──────┼─────────┼─────────┤
│ Read-Write-Listener │ 3306 │ 0.0.0.0 │ Running │
└─────────────────────┴──────┴─────────┴─────────┘

And for Round-Robin-Service:

 maxctrl: list listeners Round-Robin-Service
┌──────────────────────┬──────┬─────────┬─────────┐
│ Name                 │ Port │ Host    │ State   │
├──────────────────────┼──────┼─────────┼─────────┤
│ Round-Robin-Listener │ 3307 │ 0.0.0.0 │ Running │
└──────────────────────┴──────┴─────────┴─────────┘

Unlike other objects in MaxScale, the listener does not have a "show" and "alter" commands since it is a fairly simple object.

Create a Listener

Make sure a service has been created. In this example, taken from the Create Service section above, we will create a listener so MaxScale will listen on port 3307 to process the MariaDB connections in a round-robin fashion:

 maxctrl: create listener Round-Robin-Service Round-Robin-Listener 3307
OK

Delete a Listener

To delete a listener, use the "destroy listener" command with the respective service name and listener name:

 maxctrl: destroy listener Round-Robin-Service Round-Robin-Listener
OK

This concludes this episode of basic MaxScale management tasks for MariaDB Cluster. In the next series, we are going to cover the MaxScale advanced management tasks like service filters, MaxScale user management and so on.