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Create combined read-write splitting routing tutorial

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The read-write splitting routing tutorial is a combination of the two
different read-write splitting routing tutorials. As with the connection
routing tutorial, this should reduce the maintenance burden.
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Markus Mäkelä
2018-03-09 12:30:33 +02:00
parent b4ac1b4d07
commit fe2dfe03f4
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7
Documentation/Tutorials/Connection-Routing-Tutorial.md
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@ -34,9 +34,10 @@ that will be directed to a server where writes can be sent and another that will
load balance between all servers. To achieve this, we need to define two load balance between all servers. To achieve this, we need to define two
services in the configuration file. services in the configuration file.
Create the following two sections in your configuration file. The section names Create the following two sections in your configuration file. The section
are the names of the services themselves and should be meaningful to the names are the names of the services themselves and should be meaningful to
administrator. For this tutorial, we use the `Write-Service` and `Read-Service` names for our services. the administrator. For this tutorial, we use the `Write-Service` and
`Read-Service` names for our services.
``` ```
[Write-Service] [Write-Service]

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# Read/Write Splitting with MariaDB MaxScale
The object of this tutorial is to have a system that appears to the client as a
single database. MariaDB MaxScale will split the statements such that write
statements will be sent to the current master server in the replication cluster
and read statements will be balanced across the rest of the servers.
## Setting up MariaDB MaxScale
The first part of this tutorial is covered in [MariaDB MaxScale Tutorial](MaxScale-Tutorial.md).
Please read it and follow the instructions for setting up MariaDB MaxScale with
the type of cluster you want to use.
Once you have MariaDB MaxScale installed and the database users created, we can
create the configuration file for MariaDB MaxScale.
## Creating Your MariaDB MaxScale Configuration
MariaDB MaxScale reads its configuration from `/etc/maxscale.cnf`. A template
configuration is provided with the MaxScale installation.
A global `[maxscale]` section is included within every MariaDB MaxScale
configuration file; this is used to set the values of various global parameters,
perhaps the most important of these is the number of threads that MariaDB
MaxScale will use to handle client requests. To automatically configure the
thread count, use the `threads=auto` parameter.
```
[maxscale]
threads=auto
```
The first step is to create a Read/Write Splitter service. Create the following
section in your configuration file. The section name is the names of the service
and should be meaningful to the administrator. For this tutorial, we use the
`Splitter-Service` name for our service.
```
[Splitter-Service]
type=service
router=readwritesplit
servers=dbserv1, dbserv2, dbserv3
user=maxscale
password=maxscale_pw
```
The router module we use for this service is `readwritesplit`.
The services must be provided with the list of servers where queries
will be routed to. The server names given here are the names of server sections
in the configuration file (to be defined later) and not the physical hostnames
or addresses of the servers.
The final part of the service configuration is the `user` and `password`
parameters that define the credentials that the service will use to populate the
user authentication data. To create this user, execute the following SQL commands.
```
CREATE USER 'maxscale'@'%' IDENTIFIED BY 'maxscale_pw';
GRANT SELECT ON mysql.user TO 'maxscale'@'%';
GRANT SELECT ON mysql.db TO 'maxscale'@'%';
GRANT SELECT ON mysql.tables_priv TO 'maxscale'@'%';
GRANT SHOW DATABASES ON *.* TO 'maxscale'@'%';
```
**Note:** For increased security [encrypt your passwords in the configuration file](Encrypting-Passwords.md).
This completes the service definition, however listening ports must be
associated with the service in order to allow network connections. This is done
by creating a separate listener section in the configuration file. A service may
have multiple listeners but for this tutorial we will only need one.
```
[Splitter-Listener]
type=listener
service=Splitter-Service
protocol=MariaDBClient
port=3306
```
The `service` parameter tells to which service the listener connects to. For the
`Splitter-Listener` we set it to `Splitter-Service`.
A listener must also define the protocol module it will use for the incoming
network protocol (must be the `MariaDBClient` protocol for all database
listeners) as well as the the network port to listen on.
Additionally, the `address` parameter may be given if the listener is required
to bind to a particular network interface when the host machine has multiple
network interfaces. The default behavior is to listen on all network interfaces
(the IPv6 address `::`).
## Configuring the Monitor and Servers
The next step is the configuration of the monitor and the servers that the
service uses. This depends on the type of cluster you use with MaxScale.
For master-slave clusters read the
[Configuring MariaDB Monitor](Configuring-MariaDB-Monitor.md)
tutorial. If you are using a Galera cluster, read the
[Configuring Galera Monitor](Configuring-Galera-Monitor.md)
tutorial instead.
## Configuring the Administrative Interface
The MaxAdmin configuration is described in the
[Configuring MaxAdmin](Configuring-MaxAdmin.md) document.
## Starting MariaDB MaxScale
Upon completion of the configuration process MariaDB MaxScale is ready to be
started for the first time. For newer systems that use systemd, use the _systemctl_ command.
```
sudo systemctl start maxscale
```
For older SysV systems, use the _service_ command.
```
sudo service maxscale start
```
If MaxScale fails to start, check the error log in
`/var/log/maxscale/maxscale.log` to see if any errors are detected in the
configuration file. The `maxadmin` command may be used to confirm that MariaDB
MaxScale is running and the services, listeners and servers have been correctly
configured.
```
% sudo maxadmin list services
Services.
--------------------------+-------------------+--------+----------------+-------------------
Service Name | Router Module | #Users | Total Sessions | Backend databases
--------------------------+-------------------+--------+----------------+-------------------
Splitter-Service | readwritesplit | 1 | 1 | dbserv1, dbserv2, dbserv3
CLI | cli | 2 | 3 |
--------------------------+-------------------+--------+----------------+-------------------
% sudo maxadmin list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server | Address | Port | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
dbserv1 | 192.168.2.1 | 3306 | 0 | Running, Slave
dbserv2 | 192.168.2.2 | 3306 | 0 | Running, Master
dbserv3 | 192.168.2.3 | 3306 | 0 | Running, Slave
-------------------+-----------------+-------+-------------+--------------------
% sudo maxadmin list listeners
Listeners.
---------------------+---------------------+--------------------+-----------------+-------+--------
Name | Service Name | Protocol Module | Address | Port | State
---------------------+---------------------+--------------------+-----------------+-------+--------
Splitter-Listener | Splitter-Service | MariaDBClient | * | 3306 | Running
CLI-Listener | CLI | maxscaled | default | 0 | Running
---------------------+---------------------+--------------------+-----------------+-------+--------
```
MariaDB MaxScale is now ready to start accepting client connections and routing
them to the cluster. More options may be found in the
[Configuration Guide](../Getting-Started/Configuration-Guide.md)
and in the [readwritesplit module documentation](../Routers/ReadWriteSplit.md).
More detail on the use of `maxadmin` can be found in the
[MaxAdmin](../Reference/MaxAdmin.md) document.