Configure ProxySQL 1.x.x

This tutorial describes how to configure ProxySQL with three Percona XtraDB Cluster nodes.

Node	Host name	IP address
Node 1	pxc1	192.168.70.61
Node 2	pxc2	192.168.70.62
Node 3	pxc3	192.168.70.63
Node 4	proxysql	192.168.70.64

ProxySQL can be configured either using etc/proxysql-admin.cnf or using the admin interface. The admin interface can change the configuration dynamically and there is no need to restart the proxy.

To connect to the ProxySQL admin interface, use the mysql client. You can either connect to the admin interface from a Percona XtraDB Cluster node that already has the mysql client installed (Node 1, Node 2, Node 3) or install the client on Node 4 and connect locally. For this tutorial, install Percona XtraDB Cluster on Node 4:

On Debian-derived distributionsOn Red Hat-derived distributions

    [root@proxysql ~]# apt install percona-xtradb-cluster-client

    [root@proxysql ~]# yum install percona-xtradb-cluster-client

To connect to the admin interface, use the credentials, host name, and port specified in the ProxySQL global variables.

Do not use the default credentials in production.

The following example shows how to connect to the ProxySQL admin interface with the default credentials:

root@proxysql:~# mysql -u admin -padmin -h 127.0.0.1 -P 6032

Expected output

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.1.30 (ProxySQL Admin Module)

Copyright (c) 2009-2022 Percona LLC and/or its affiliates
Copyright (c) 2000, 2022, Oracle and/or its affiliates.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql@proxysql>

To see the ProxySQL databases and tables use the following commands:

mysql@proxysql> SHOW DATABASES;

Expected output

+-----+---------+-------------------------------+
| seq | name    | file                          |
+-----+---------+-------------------------------+
| 0   | main    |                               |
| 2   | disk    | /var/lib/proxysql/proxysql.db |
| 3   | stats   |                               |
| 4   | monitor |                               |
+-----+---------+-------------------------------+
4 rows in set (0.00 sec)

mysql@proxysql> SHOW TABLES;

Expected output

+--------------------------------------+
| tables                               |
+--------------------------------------+
| global_variables                     |
| mysql_collations                     |
| mysql_query_rules                    |
| mysql_replication_hostgroups         |
| mysql_servers                        |
| mysql_users                          |
| runtime_global_variables             |
| runtime_mysql_query_rules            |
| runtime_mysql_replication_hostgroups |
| runtime_mysql_servers                |
| runtime_scheduler                    |
| scheduler                            |
+--------------------------------------+
12 rows in set (0.00 sec)

ProxySQL has three areas where the configuration can reside:

• MEMORY (your current working place)

• RUNTIME (the production settings)

• DISK (durable configuration saved in a SQLite database)

When you change a parameter, you change it in the MEMORY area. This method allows you to test the changes before pushing the change to production (RUNTIME) or to disk.

Add cluster nodes to ProxySQL

To configure the backend Percona XtraDB Cluster nodes in ProxySQL, insert the corresponding records into the mysql_servers table.

ProxySQL uses the concept of hostgroups to group cluster nodes. This approach enables balancing the load in a cluster by routing different types of traffic to different groups.

There are many ways you can configure hostgroups (for example, master and slaves, read and write load, etc.) and a node can be a member of multiple hostgroups.

This example adds three Percona XtraDB Cluster nodes to the default hostgroup (0), which receives both write and read traffic:

mysql@proxysql> INSERT INTO mysql_servers(hostgroup_id, hostname, port) VALUES (0,'192.168.70.61',3306);
mysql@proxysql> INSERT INTO mysql_servers(hostgroup_id, hostname, port) VALUES (0,'192.168.70.62',3306);
mysql@proxysql> INSERT INTO mysql_servers(hostgroup_id, hostname, port) VALUES (0,'192.168.70.63',3306);

To see the nodes:

mysql@proxysql> SELECT * FROM mysql_servers;

Expected output

hostgroup_id	hostname	port	status	weight	compression	max_connections	max_replication_lag	use_ssl	max_latency_ms	comment
192.168.70.61	3306	ONLINE	1	0	1000	0	0
192.168.70.62	3306	ONLINE	1	0	1000	0	0
192.168.70.63	3306	ONLINE	1	0	1000	0	0

Create a ProxySQL monitoring user

To enable monitoring of Percona XtraDB Cluster nodes in ProxySQL, create a user with the USAGE privilege on any node in the cluster and configure the user in ProxySQL.

The following example shows how to add a monitoring user on Node 2:

mysql@pxc2> CREATE USER 'proxysql'@'%' IDENTIFIED BY 'ProxySQLPa55';
mysql@pxc2> GRANT USAGE ON *.* TO 'proxysql'@'%';

The following example shows how to configure this user on the ProxySQL node:

mysql@proxysql> UPDATE global_variables SET variable_value='proxysql'
              WHERE variable_name='mysql-monitor_username';
mysql@proxysql> UPDATE global_variables SET variable_value='ProxySQLPa55'
              WHERE variable_name='mysql-monitor_password';

To load this configuration at runtime, issue a LOAD command. Issue a SAVE command to save these changes to disk, this operation ensures that the changes persist after ProxySQL shuts down.

mysql@proxysql> LOAD MYSQL VARIABLES TO RUNTIME;
mysql@proxysql> SAVE MYSQL VARIABLES TO DISK;

Check the monitoring logs to ensure that monitoring is enabled:

mysql@proxysql> SELECT * FROM monitor.mysql_server_connect_log ORDER BY time_start_us DESC LIMIT 6;

Expected output

+---------------+------+------------------+----------------------+---------------+
| hostname      | port | time_start_us    | connect_success_time | connect_error |
+---------------+------+------------------+----------------------+---------------+
| 192.168.70.61 | 3306 | 1469635762434625 | 1695                 | NULL          |
| 192.168.70.62 | 3306 | 1469635762434625 | 1779                 | NULL          |
| 192.168.70.63 | 3306 | 1469635762434625 | 1627                 | NULL          |
| 192.168.70.61 | 3306 | 1469635642434517 | 1557                 | NULL          |
| 192.168.70.62 | 3306 | 1469635642434517 | 2737                 | NULL          |
| 192.168.70.63 | 3306 | 1469635642434517 | 1447                 | NULL          |
+---------------+------+------------------+----------------------+---------------+
6 rows in set (0.00 sec)

mysql> SELECT * FROM monitor.mysql_server_ping_log ORDER BY time_start_us DESC LIMIT 6;

Expected output

+---------------+------+------------------+-------------------+------------+
| hostname      | port | time_start_us    | ping_success_time | ping_error |
+---------------+------+------------------+-------------------+------------+
| 192.168.70.61 | 3306 | 1469635762416190 | 948               | NULL       |
| 192.168.70.62 | 3306 | 1469635762416190 | 803               | NULL       |
| 192.168.70.63 | 3306 | 1469635762416190 | 711               | NULL       |
| 192.168.70.61 | 3306 | 1469635702416062 | 783               | NULL       |
| 192.168.70.62 | 3306 | 1469635702416062 | 631               | NULL       |
| 192.168.70.63 | 3306 | 1469635702416062 | 542               | NULL       |
+---------------+------+------------------+-------------------+------------+
6 rows in set (0.00 sec)

The previous examples show that ProxySQL is able to connect and ping the nodes you added.

To enable monitoring of these nodes, load them at runtime:

mysql@proxysql> LOAD MYSQL SERVERS TO RUNTIME;

Create a ProxySQL client user

ProxySQL must have users that can access backend nodes to manage connections.

To add a user, insert credentials into mysql_users table:

mysql@proxysql> INSERT INTO mysql_users (username,password) VALUES ('sbuser','sbpass');

Expected output

Query OK, 1 row affected (0.00 sec)

Note

ProxySQL currently does not encrypt passwords.

Load the user into runtime space and save these changes to disk to ensure that the user account persists after ProxySQL shuts down:

mysql@proxysql> LOAD MYSQL USERS TO RUNTIME;
mysql@proxysql> SAVE MYSQL USERS TO DISK;

To confirm that the user has been set up correctly, you can try to log in:

root@proxysql:~# mysql -u sbuser -psbpass -h 127.0.0.1 -P 6033

Expected output

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 1491
Server version: 5.1.30 (ProxySQL)

Copyright (c) 2009-2016 Percona LLC and/or its affiliates
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

To provide read/write access to the cluster for ProxySQL, add this user on one of the Percona XtraDB Cluster nodes:

mysql@pxc3> CREATE USER 'sbuser'@'192.168.70.64' IDENTIFIED BY 'sbpass';

Expected output

Query OK, 0 rows affected (0.01 sec)

mysql@pxc3> GRANT ALL ON *.* TO 'sbuser'@'192.168.70.64';

Expected output

Query OK, 0 rows affected (0.00 sec)

Add Galera support in ProxySQL 1.x.x

ProxySQL 2.x.x supports monitoring the status Percona XtraDB Cluster nodes. ProxySQL 1.x.x can’t detect a node which isn’t in Synced state. To monitor the status of Percona XtraDB Cluster nodes in ProxySQL 1.x.x, use the script proxysql_galera_checker.

To use this script, load it into ProxySQL scheduler.

The following example shows how you can load the script for default ProxySQL 1.x.x configuration:

mysql> INSERT INTO scheduler (active,interval_ms,filename,arg1,comment)
VALUES (1,10000,'/usr/bin/proxysql_galera_checker','--config-file=/etc/proxysql-admin.cnf
--write-hg=10 --read-hg=11 --writer-count=1 --mode=singlewrite
--priority=192.168.100.20:3306,192.168.100.40:3306,192.168.100.10:3306,192.168.100.30:3306
--log=/var/lib/proxysql/cluster_one_proxysql_galera_check.log','cluster_one');

This scheduler script accepts the following options in the arg1 argument:

Option	Name	Required	Description
--config-file	Configuration file	Yes	Specify proxysql-admin conifiguration file
--write-hg	HOSTGROUP WRITERS	No	Specify ProxySQL write hostgroup
--read-hg	HOSTGROUP READERS	No	Specify ProxySQL read hostgroup
--writer-count	NUMBER WRITERS	No	Specify the write node count. The options are: 0 for loadbal mode and 1 for singlewrite mode.
--mode	MODE	No	Specify ProxySQL read/write configuration mode
--priority	WRITER PRIORITY	No	Specify write notes priority
--log	LOG FILE	No	Specify proxysql_galera_checker log file

Note

Specify the cluster name in comment column.

To load the scheduler changes into the runtime space:

mysql@proxysql> LOAD SCHEDULER TO RUNTIME;

To make sure that the script has been loaded, review the runtime_scheduler table:

mysql@proxysql> SELECT * FROM scheduler\G

Expected output

*************************** 1. row ***************************
        id: 1
    active: 1
interval_ms: 10000
filename: /bin/proxysql_galera_checker
    arg1: --config-file=/etc/proxysql-admin.cnf --write-hg=10 --read-hg=11
            --writer-count=1 --mode=singlewrite
            --priority=192.168.100.20:3306,192.168.100.40:3306,192.168.100.10:3306,192.168.100.30:3306
            --log=/var/lib/proxysql/cluster_one_proxysql_galera_check.log
    arg2: NULL
    arg3: NULL
    arg4: NULL
    arg5: NULL
    comment: cluster_one
1 row in set (0.00 sec)

Review the status of available nodes:

mysql@proxysql> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;

Expected output

+--------------+---------------+------+--------+
| hostgroup_id | hostname      | port | status |
+--------------+---------------+------+--------+
| 0            | 192.168.70.61 | 3306 | ONLINE |
| 0            | 192.168.70.62 | 3306 | ONLINE |
| 0            | 192.168.70.63 | 3306 | ONLINE |
+--------------+---------------+------+--------+
3 rows in set (0.00 sec)

Each node can have the following status:

ONLINE

Backend node is fully operational.

SHUNNED

backend node is temporarily taken out of use, because either too many
connection errors happened in a short time, or replication lag exceeded the
allowed threshold.

OFFLINE_SOFT

New incoming connections aren’t accepted, while existing connections are kept
until they become inactive. In other words, connections are kept in use until
the current transaction is completed.  This allows to gracefully detach a
backend node.

OFFLINE_HARD

Existing connections are dropped, and new incoming connections aren’t
accepted.  This is equivalent to deleting the node from a hostgroup, or
temporarily taking it out of the hostgroup for maintenance.

Test the cluster with sysbench

Sysbench is designed to run CPU, memory and I/O test and has the option to run Online Transaction Processing (OLTP) workloads on a MySQL database. Install Sysbench from Percona software repositories:

On Debian-derived distributionsOn Red Hat-derived distributions

root@proxysql:~#> apt install sysbench

[root@proxysql ~]#> yum install sysbench

Sysbench requires the ProxySQL client user credentials from Create a ProxySQL client user.

1. Create a database on one of the Percona XtraDB Cluster nodes. Use this database for testing.

   mysql@pxc1> CREATE DATABASE sbtest;
   

2. Populate the table with data for the benchmark on the ProxySQL node:

   root@proxysql:~#> sysbench --report-interval=5 --num-threads=4 \
   --num-requests=0 --max-time=20 \
   --test=/usr/share/doc/sysbench/tests/db/oltp.lua \
   --mysql-user='sbuser' --mysql-password='sbpass' \
   --oltp-table-size=10000 --mysql-host=127.0.0.1 --mysql-port=6033 \
   prepare
   

3. Run the benchmark on the ProxySQL node:

   root@proxysql:~#> sysbench --report-interval=5 --num-threads=4 \
   --num-requests=0 --max-time=20 \
   --test=/usr/share/doc/sysbench/tests/db/oltp.lua \
   --mysql-user='sbuser' --mysql-password='sbpass' \
   --oltp-table-size=10000 --mysql-host=127.0.0.1 --mysql-port=6033 \
   run
   

ProxySQL stores collected data in the stats schema:

mysql@proxysql> SHOW TABLES FROM stats;

Expected output

+--------------------------------+
| tables                         |
+--------------------------------+
| stats_mysql_query_rules        |
| stats_mysql_commands_counters  |
| stats_mysql_processlist        |
| stats_mysql_connection_pool    |
| stats_mysql_query_digest       |
| stats_mysql_query_digest_reset |
| stats_mysql_global             |
+--------------------------------+

For example, to see the number of commands that run on the cluster:

Automatic fail-over

ProxySQL automatically detects if a node isn’t available or if the node isn’t synced with the cluster.

You can check the status of all available nodes by running:

mysql@proxysql> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;

Expected output

+--------------+---------------+------+--------+
| hostgroup_id | hostname      | port | status |
+--------------+---------------+------+--------+
| 0            | 192.168.70.61 | 3306 | ONLINE |
| 0            | 192.168.70.62 | 3306 | ONLINE |
| 0            | 192.168.70.63 | 3306 | ONLINE |
+--------------+---------------+------+--------+
3 rows in set (0.00 sec)

To test problem detection and fail-over mechanism, shut down Node 3:

root@pxc3:~# service mysql stop

ProxySQL detects that the node is down and updates the node’s status to OFFLINE_SOFT:

mysql@proxysql> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;

Expected output

+--------------+---------------+------+--------------+
| hostgroup_id | hostname      | port | status       |
+--------------+---------------+------+--------------+
| 0            | 192.168.70.61 | 3306 | ONLINE       |
| 0            | 192.168.70.62 | 3306 | ONLINE       |
| 0            | 192.168.70.63 | 3306 | OFFLINE_SOFT |
+--------------+---------------+------+--------------+
3 rows in set (0.00 sec)

Start Node 3 again:

root@pxc3:~#> service mysql start

The script detects the change and marks the node as ONLINE:

mysql@proxysql> SELECT hostgroup_id,hostname,port,status FROM mysql_servers;

Expected output

+--------------+---------------+------+--------+
| hostgroup_id | hostname      | port | status |
+--------------+---------------+------+--------+
| 0            | 192.168.70.61 | 3306 | ONLINE |
| 0            | 192.168.70.62 | 3306 | ONLINE |
| 0            | 192.168.70.63 | 3306 | ONLINE |
+--------------+---------------+------+--------+
3 rows in set (0.00 sec)

Assisted maintenance mode

For maintenance, identify that node, update its status in ProxySQL to OFFLINE_SOFT, wait for ProxySQL to divert traffic from this node, and then initiate the shutdown or perform maintenance tasks. Percona XtraDB Cluster includes a special maintenance mode for nodes that enables you to take a node down without adjusting ProxySQL manually. This mode is controlled by the pxc_maint_mode variable, which is monitored by ProxySQL and can be set to one of the following values:

• DISABLED: This is the default state that tells ProxySQL to route traffic to the node as usual.

• SHUTDOWN: This state is set automatically when you initiate node shutdown.

• MAINTENANCE: You can manually change to this state if you need to perform maintenance on a node without shutting it down.

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Last update: 2024-04-18