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Rephrased some of the text. Moved some parts to the general tutorial to avoid
repeating it in the two specialized tutorials.
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Esa Korhonen
2019-06-18 14:05:52 +03:00
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Documentation/Tutorials/Connection-Routing-Tutorial.md
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# Connection Routing with MariaDB MaxScale
The object of this tutorial is to have a system that has two ports
available, one for write connections and another for read connection that
are load balanced across all servers.
The goal of this tutorial is to configure a system that has two ports available, one for
write connections and another for read connections. The read connections are load-
balanced across slave 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.
This tutorial is a part of the [MariaDB MaxScale Tutorial](MaxScale-Tutorial.md).
Please read it and follow the instructions. Return here once basic setup is complete.
Once you have MariaDB MaxScale installed and the database users created, we can
create the configuration file for MariaDB MaxScale.
## Configuring services
## Creating Your MariaDB MaxScale Configuration
We want two services and ports to which the client application can connect. One service
routes client connections to the master server, the other load balances between slave
servers. To achieve this, we need to define two services in the configuration file.
MariaDB MaxScale reads its configuration from `/etc/maxscale.cnf`. A template
configuration is provided with the MaxScale installation.
A global `[maxscale]` section is included in 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
```
## Configuring Servers
Read the [Configuring Servers](Configuring-Servers.md) mini-tutorial to see how
the servers are configured.
## Configuring the Monitor
The next step is the configuration of the monitor. 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 Service
We want two different ports to which the client application can connect; one
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
services in the configuration file.
Create the following two sections in your configuration file. The section
names are the names of the services themselves and should be meaningful to
the administrator. For this tutorial, we use the `Write-Service` and
`Read-Service` names for our services.
Create the following two sections in your configuration file. The section names are the
names of the services and should be meaningful. For this tutorial, we use the names
*Write-Service* and *Read-Service*.
```
[Write-Service]
@ -75,32 +37,28 @@ user=maxscale
password=maxscale_pw
```
The router module for these two sections is identical, the `readconnroute`
module.
*router* defines the routing module used. Here we use *readconnroute* for
connection-level routing.
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.
A service needs a list of servers to route queries to. The server names must
match the names of server sections in the configuration file and not the hostnames or
addresses of the servers.
In order to instruct the router to which servers it should route we must add the
`router_options` parameter to the service. This parameter tells what sort of
servers the service will use. For the write service we use the _master_ type and
for the read service we use the _slave_ type.
The *router_options*-parameter tells the *readconnroute*-module which servers it should
route a client connection to. For the write service we use the _master_-type and for the
read service the _slave_-type.
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
The *user* and *password* parameters define the credentials the service uses to populate
user authentication data. These users were created at the start of the
[MaxScale Tutorial](MaxScale-Tutorial.md).
**Note:** For increased security [encrypt your passwords in the configuration file](Encrypting-Passwords.md).
For increased security, see [password encryption](Encrypting-Passwords.md).
## Configuring the Listener
In order to allow network connections to the service, we must associate a network
port with the service. 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 per service.
To allow network connections to a service, a network ports must be associated with it.
This is done by creating a separate listener section in the configuration file. A service
may have multiple listeners but for this tutorial one per service is enough.
```
[Write-Listener]
@ -116,84 +74,17 @@ protocol=MariaDBClient
port=3307
```
The `service` parameter tells to which service the listener connects to. For the
`Write-Listener` we set it to `Write-Service` and for the `Read-Listener` we set
it to `Read-Service`.
The *service* parameter tells which service the listener connects to. For the
*Write-Listener* we set it to *Write-Service* and for the *Read-Listener* we set
it to *Read-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.
A listener must define the protocol module it uses. This must be *MariaDBClient* for all
database listeners. *port* defines 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 Administrative Interface
The MaxAdmin configuration is described in the
[Configuring MaxAdmin](Configuring-MaxAdmin.md) document.
The optional *address*-parameter defines the local address the listener should bind to.
This may be required when the host machine has multiple network interfaces. The
default behavior is to listen on all network interfaces (the IPv6 address `::`).
## 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
--------------------------+-------------------+--------+----------------+-------------------
Write-Service | readconnroute | 1 | 1 | dbserv1, dbserv2, dbserv3
Read-Service | readconnroute | 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
---------------------+---------------------+--------------------+-----------------+-------+--------
Write-Listener | Write-Service | MariaDBClient | * | 3306 | Running
Read-Listener | Read-Service | MariaDBClient | * | 3307 | 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 [readconnroute module documentation](../Routers/ReadConnRoute.md).
More detail on the use of `maxadmin` can be found in the
[MaxAdmin](../Reference/MaxAdmin.md) document.
For the last steps, please return to [MaxScale Tutorial](MaxScale-Tutorial.md).