Deploy MaxScale 2.5 with Galera Monitor and Read/Write Split Router¶

These instructions detail the deployment of MariaDB MaxScale 2.5 in a MaxScale Instance with Galera Monitor and Read/Write Split Router on a range of supported Operating Systems. Instructions for specific operating systems are available.

These instructions detail how to deploy MariaDB MaxScale as a load balancing and high availability solution for Galera Cluster.

Prerequisites¶

These instructions assume that the back-end MariaDB Server instances have already been deployed.

See the following resources for how to deploy Galera Cluster nodes:

MariaDB Platform Components¶

These instructions detail the deployment of the following MariaDB Platform components:

Component	Description
MariaDB MaxScale 2.5	MariaDB MaxScale is an advanced database proxy, firewall, and query router.

MaxScale Components¶

These instructions detail the deployment of MaxScale with the following components:

Component	Description
Galera Monitor (galeramon)	It monitors Galera Cluster deployments. It supports MariaDB Enterprise Cluster. It supports MariaDB Galera Cluster.
Read/Write Split Router (readwritesplit)	It increases the read-only processing capability of a cluster while maintaining consistency. It splits the query load into read and write queries. It routes read queries to multiple replica servers. It routes write queries to a single primary server. If the primary server changes, then it routes write queries to the new primary server.

Term Definitions¶

Term	Definition
MaxScale instance	MariaDB MaxScale running by itself on a single host. It interacts with other hosts, such as deployments using MariaDB Replication, Galera Cluster, and ColumnStore. It serves as the database proxy and load balancer.

Installation¶

MariaDB Corporation provides package repositories for YUM (RHEL/CentOS), APT (Debian/Ubuntu), and ZYpp (SLES).

Install via YUM (RHEL/CentOS)¶

Retrieve your Customer Download Token at https://customers.mariadb.com/downloads/token/ and substitute for customer_download_token in the following directions.

Configure the YUM package repository.

Installable versions of MariaDB MaxScale are 2.5, 2.4, and 2.3. Pass the version you want to install using the --mariadb-maxscale-version flag to the mariadb_es_repo_setup script. The following directions reference 2.5.

To configure YUM package repositories:

$ sudo yum install wget

$ wget https://dlm.mariadb.com/enterprise-release-helpers/mariadb_es_repo_setup

$ echo "957bc29576e8fd320fa18e35fa49b5733f3c8eeb4ca06792fb1f05e089c810ff  mariadb_es_repo_setup" \
    | sha256sum -c -

$ chmod +x mariadb_es_repo_setup

$ sudo ./mariadb_es_repo_setup --token="customer_download_token" --apply \
   --mariadb-maxscale-version="2.5"

Install MariaDB MaxScale and package dependencies:
```
$ sudo yum install maxscale
```
Configure MaxScale.

Installation only loads MariaDB MaxScale to the system. MariaDB MaxScale requires configuration before MaxScale is ready for use.

See Configuration.

Install via APT (Debian/Ubuntu)¶

Retrieve your Customer Download Token at https://customers.mariadb.com/downloads/token/ and substitute for customer_download_token in the following directions.

Configure the APT package repository.

Installable versions of MariaDB MaxScale are 2.5, 2.4 and 2.3. Pass the version you want to install using the --mariadb-maxscale-version flag to the mariadb_es_repo_setup script. The following directions reference 2.5.

To configure APT package repositories:

$ sudo apt install wget

$ wget https://dlm.mariadb.com/enterprise-release-helpers/mariadb_es_repo_setup

$ echo "957bc29576e8fd320fa18e35fa49b5733f3c8eeb4ca06792fb1f05e089c810ff  mariadb_es_repo_setup" \
    | sha256sum -c -

$ chmod +x mariadb_es_repo_setup

$ sudo ./mariadb_es_repo_setup --token="customer_download_token" --apply \
   --mariadb-maxscale-version="2.5"

$ sudo apt update

Install MariaDB MaxScale and package dependencies:
```
$ sudo apt install maxscale
```
Configure MaxScale.

Installation only loads MariaDB MaxScale to the system. MariaDB MaxScale requires configuration before MaxScale is ready for use.

See Configuration.

Install via ZYpp (SLES)¶

Retrieve your Customer Download Token at https://customers.mariadb.com/downloads/token/ and substitute for customer_download_token in the following directions.

Configure the ZYpp package repository.

To configure ZYpp package repositories:

$ sudo zypper install wget

$ wget https://dlm.mariadb.com/enterprise-release-helpers/mariadb_es_repo_setup

$ echo "957bc29576e8fd320fa18e35fa49b5733f3c8eeb4ca06792fb1f05e089c810ff  mariadb_es_repo_setup" \
    | sha256sum -c -

$ chmod +x mariadb_es_repo_setup

$ sudo ./mariadb_es_repo_setup --token="customer_access_token" --apply \
   --mariadb-maxscale-version="2.5"

Install MariaDB MaxScale and package dependencies:
```
$ sudo zypper install maxscale
```
Configure MaxScale.

Installation only loads MariaDB MaxScale to the system. MariaDB MaxScale requires configuration before MaxScale is ready for use.

See Configuration.

Configuration¶

MariaDB MaxScale's parameters can be configured in two ways:

All parameters can be set in a configuration file (such as the /etc/maxscale.cnf file). When the configuration file is updated, the MaxScale instance must be restarted to apply the changes.
If a parameter supports dynamic changes, it can be set on-the-fly using the MaxCtrl utility.

Configuring MaxScale's Global Parameters¶

Determine which global parameters you need to configure.

Useful global parameters for MariaDB MaxScale:

Parameter	Description
local_address	Sets the local IP address or network interface to use when connecting to MariaDB Enterprise Servers.
admin_enabled	Sets whether the MaxScale Instance supports the REST API. Disable to block access.
admin_host	Sets the network interface used by the REST API.
admin_port	Sets the port used by the REST API.
admin_auth	Sets whether the REST API uses HTTP Basic Access authentication. Users can be created wih maxctrl.

Set your global parameters in maxscale.cnf.

MariaDB MaxScale's global parameters, which apply to the whole instance, are set in the [maxscale] configuration group:

For example:
```
[maxscale]
admin_auth    = true
```

Configuring Servers¶

Determine which server parameters you need to configure.

Mandatory parameters for Server objects:

Parameter	Description
`type`	Set the module type to `server`.
`address`	Set the IP address for the MariaDB Enterprise Server.
`port`	Set the port the MariaDB Enterprise Server listens on.
`protocol`	Set the protocol to `MariaDBBackend` to connect the Server.

Set your server parameters in maxscale.cnf.

For each Server in your deployment, add a new uniquely-named configuration group to the MaxScale Instance. The name of the configuration group is arbitrary, but it cannot contain any white space. Use whatever terms you find most convenient, but it is most common to use names like serverN or the server's host name.

For example:
```
[server1]
type     = server
address  = 192.0.2.2
port     = 3306
protocol = MariaDBBackend
```

Configuring Galera Monitor¶

Determine which parameters for Galera Monitor (galeramon) you need to configure.

Mandatory parameters for Galera Monitor (galeramon):

Parameter	Description
`type`	Set the type to `monitor`.
`module`	Set to `galeramon` for MariaDB Enterprise Cluster.
`servers`	Set to a comma-separated list of the Server object names.
`user`	Set to the user MariaDB MaxScale uses to connect to the Servers.
`password`	Set to the password MariaDB MaxScale uses to authenticate on the Servers.

Useful parameters for Galera Monitor (galeramon):

Parameter	Description
`disable_master_failback`	If a node marked as master inside MaxScale happens to fail and the master status is assigned to another node MaxScale will normally return the master status to the original node after it comes back up. With this option enabled, if the master status is assigned to a new node it will not be reassigned to the original node for as long as the new master node is running.
`available_when_donor`	This option allows Galera nodes to be used normally when they are donors in an SST operation when the SST method is non-blocking.

Set your Galera Monitor parameters in maxscale.cnf.

Add a new uniquely-named configuration group for the monitor to the MaxScale Instance. The name of the configuration group is arbitrary, but it cannot contain any white space. Use whatever terms you find most convenient, but it is most common to use names like cluster-monitor.

For example:
```
[cluster-monitor]
type           = monitor
module         = galeramon
servers        = server1,server2,server3
user           = maxscale
password       = max_passwd
```

Configuring Read/Write Split Router¶

Determine which parameters for Read/Write Split Router (readwritesplit) you need to configure.

Mandatory parameters for Read/Write Split Router (readwritesplit):

Parameter	Description
`type`	Set the module type as `service`.
`router`	Use to set the type of router you want to use for the service. For the Read/Write Split router, set to `readwritesplit`.
`servers`	Set as a comma-separated list of the Server object names.
`user`	Set the user you want the MaxScale Instance to use when connecting to Servers.
`password`	Set the password you want the MaxScale Instance to use in authentication when conecting to Servers.

Set your Read/Write Split Router parameters in maxscale.cnf.

Add a new uniquely-named configuration group for the router to the MaxScale Instance. The name of the configuration group is arbitrary, but it cannot contain any white space. Use whatever terms you find most convenient, but it is most common to use names like split-router.

For example:
```
[split-router]
type     = service
router   = readwritesplit
servers  = server1,server2,server3
user     = maxscale
password = max_passwd
```

Configuring the Router's Listener¶

Determine which parameters for the listener you need to configure.

Mandatory parameters for the listener:

Parameter	Description
`type`	Set the module type as a `listener`.
`service`	Use this parameter to connect the listener to a configured routing service.
`protocol`	Set this parameter to `MariaDBClient` to handle incoming client connections.
`port`	Set this parameter to specify the port you want the MaxScale Instance to listen on.

Set your listener parameters in maxscale.cnf.

Add a new uniquely-named configuration group for the listener to the MaxScale Instance. The name of the configuration group is arbitrary, but it cannot contain any white space. Use whatever terms you find most convenient, but it is most common to use names like split-router-listener.

For example:
```
[split-router-listener]
type     = listener
service  = split-router
protocol = MariaDBClient
port     = 3306
```

Configuring the User Account¶

On each back-end MariaDB server, create the user account used by the monitor and the router using the CREATE USER statement. Make sure that the user account can connect from the MaxScale instance's IP address:
```
CREATE USER maxscale@192.0.2.1
   IDENTIFIED BY 'max_passwd';
```

On each back-end MariaDB server, grant the required privileges to the user account used by the monitor and the router using the GRANT statement.

For the Read/Write Split Router (readwritesplit) , the global SHOW DATABASES privilege and the SELECT privilege on several of the system's privilege tables are required:

GRANT SHOW DATABASES ON *.*
     TO maxscale@192.0.2.1;
GRANT SELECT ON mysql.columns_priv
     TO maxscale@192.0.2.1;
GRANT SELECT ON mysql.db
     TO maxscale@192.0.2.1;
GRANT SELECT ON mysql.proxies_priv
     TO maxscale@192.0.2.1;
GRANT SELECT ON mysql.roles_mapping
     TO maxscale@192.0.2.1;
GRANT SELECT ON mysql.tables_priv
     TO maxscale@192.0.2.1;
GRANT SELECT ON mysql.user
     TO maxscale@192.0.2.1;

For Galera Monitor (galeramon), the global REPLICATION CLIENT privilege is sufficient for all of the monitor's functionality:

GRANT REPLICATION CLIENT ON *.*
     TO maxscale@192.0.2.1;

Starting the MaxScale Instance¶

MariaDB MaxScale installations include configuration to start, stop, restart, enable/disable on boot, and check the status of the MaxScale Instance using the operating system default process management system.

For distributions that use systemd (most supported OSes), you can manage the MaxScale process using the systemctl command:

Operation	Command
Start	`sudo systemctl start maxscale`
Stop	`sudo systemctl stop maxscale`
Restart	`sudo systemctl restart maxscale`
Enable during startup	`sudo systemctl enable maxscale`
Disable during startup	`sudo systemctl disable maxscale`
Status	`sudo systemctl status maxscale`

For distributions that use Upstart (RHEL6, CentOS 6), you can manage the MaxScale process using the service and chkconfig utilities:

Operation	Command
Start	`sudo service maxscale start`
Stop	`sudo service maxscale stop`
Restart	`sudo service maxscale restart`
Enable during startup	`sudo chkconfig --add maxscale`
Disable during startup	`sudo chkconfig --del maxscale`
Status	`sudo service maxscale status`

Testing¶

When you have MariaDB MaxScale up and running, you should test it to ensure that it is working and that weren't any issues during startup.

Checking MaxScale Status¶

Check that MaxScale is running properly by using the MaxCtrl utility:

$ sudo maxctrl show maxscale

┌──────────────┬──────────────────────────────────────────────────────────────────────┐
│ Version      │                                                               │
├──────────────┼──────────────────────────────────────────────────────────────────────┤
│ Commit       │ 61b8bbf7f63c38ca9c408674e66f3627a0b2192e                             │
├──────────────┼──────────────────────────────────────────────────────────────────────┤
│ Started At   │ Fri, 03 Jan 2020 18:05:18 GMT                                        │
├──────────────┼──────────────────────────────────────────────────────────────────────┤
│ Activated At │ Fri, 03 Jan 2020 18:05:18 GMT                                        │
├──────────────┼──────────────────────────────────────────────────────────────────────┤
│ Uptime       │ 109                                                                  │
├──────────────┼──────────────────────────────────────────────────────────────────────┤
│ Parameters   │ {                                                                    │
│              │     "libdir": "/usr/lib/x86_64-linux-gnu/maxscale",                  │
│              │     "datadir": "/var/lib/maxscale",                                  │
│              │     "process_datadir": "/var/lib/maxscale/data3850",                 │
│              │     "cachedir": "/var/cache/maxscale",                               │
│              │     "configdir": "/etc",                                             │
│              │     "config_persistdir": "/var/lib/maxscale/maxscale.cnf.d",         │
│              │     "module_configdir": "/etc/maxscale.modules.d",                   │
│              │     "piddir": "/var/run/maxscale",                                   │
│              │     "logdir": "/var/log/maxscale",                                   │
│              │     "langdir": "/var/lib/maxscale",                                  │
│              │     "execdir": "/usr/bin",                                           │
│              │     "connector_plugindir": "/usr/lib/x86_64-linux-gnu/mysql/plugin", │
│              │     "threads": 1,                                                    │
│              │     "thread_stack_size": 8388608,                                    │
│              │     "writeq_high_water": 0,                                          │
│              │     "writeq_low_water": 0,                                           │
│              │     "auth_connect_timeout": 3,                                       │
│              │     "auth_read_timeout": 1,                                          │
│              │     "auth_write_timeout": 2,                                         │
│              │     "skip_permission_checks": false,                                 │
│              │     "admin_auth": true,                                              │
│              │     "admin_enabled": true,                                           │
│              │     "admin_log_auth_failures": true,                                 │
│              │     "admin_host": "127.0.0.1",                                       │
│              │     "admin_port": 8989,                                              │
│              │     "admin_ssl_key": "",                                             │
│              │     "admin_ssl_cert": "",                                            │
│              │     "admin_ssl_ca_cert": "",                                         │
│              │     "admin_pam_readwrite_service": "",                               │
│              │     "admin_pam_readonly_service": "",                                │
│              │     "passive": false,                                                │
│              │     "query_classifier": "",                                          │
│              │     "query_classifier_cache_size": 155008819,                        │
│              │     "retain_last_statements": 0,                                     │
│              │     "dump_last_statements": "never",                                 │
│              │     "session_trace": 0,                                              │
│              │     "load_persisted_configs": true,                                  │
│              │     "max_auth_errors_until_block": 10                                │
│              │ }                                                                    │
└──────────────┴──────────────────────────────────────────────────────────────────────┘