galera_maxscale

Table of Contents

1. Description
2. Setup - The basics of getting started with galera_maxscale
   • Beginning with galera_maxscale
3. Usage - Configuration options and additional functionality
4. Reference - An under-the-hood peek at what the module is doing and how
5. Limitations - OS compatibility, etc.
6. Development - Guide for contributing to the module

Description

This module sets up and bootstrap Galera cluster and MaxScale Proxy. The subsequent management of the Galera cluster is demanded to the script galera_wizard.yp. MaxScale Proxy will be set up on 2 nodes with Keepalived. You need, at least, 5 servers and 6 ipv4 (and optionally 6 ipv6). Please read at (actual) limitations in the paragraph below.

Setup

Beginning with galera_maxscale

To setup Galera:

class { '::galera_maxscale':
  root_password    => $root_password,
  sst_password     => $sst_password,
  monitor_password => $monitor_password,
  maxscale_hosts   => $maxscale_hosts,
  maxscale_vip     => $maxscale_hosts,
  galera_hosts     => $galera_hosts,
  trusted_networks => $trusted_networks,
  manage_lvm       => true,
  vg_name          => 'rootvg',
  lv_size          => $lv_size;
}

To setup MaxScale:

class { '::galera_maxscale::maxscale::maxscale':
  trusted_networks => $trusted_networks,
  maxscale_hosts   => $maxscale_hosts,
  maxscale_vip     => $maxscale_vip,
  galera_hosts     => $galera_hosts;
}

Once you have run puppet on every node, you can manage or check the cluster using the script:

[root@test-galera01 ~]# galera_wizard.py -h
usage: galera_wizard.py [-h] [-cg] [-dr] [-je] [-be] [-jn] [-bn]

Use this script to bootstrap, join nodes within a Galera Cluster
----------------------------------------------------------------
  Avoid joining more than one node at once!

optional arguments:
  -h, --help                 show this help message and exit
  -cg, --check-galera        check if all nodes are healthy
  -dr, --dry-run             show SQL statements to run on this cluster
  -je, --join-existing       join existing Cluster
  -be, --bootstrap-existing  bootstrap existing Cluster
  -jn, --join-new            join existing Cluster
  -bn, --bootstrap-new       bootstrap new Cluster
  -f, --force                force bootstrap new or join new Cluster

Author: Massimiliano Adamo <maxadamo@gmail.com>

Usage

The module will fail on Galera with an even number of nodes and with a number of nodes lower than 3.

To setup a Galera Cluster (and optionally a MaxScale cluster with Keepalived) we need a hash. If you use hiera it will be like this:

galera_hosts:
  test-galera01.example.net:
    ipv4: '192.168.0.83'
    ipv6: '2001:123:4::6b'
  test-galera02.example.net:
    ipv4: '192.168.0.84'
    ipv6: '2001:123:4::6c'
  test-galera03.example.net:
    ipv4: '192.168.0.85'
    ipv6: '2001:123:4::6d'
maxscale_hosts:
  test-maxscale01.example.net:
    ipv4: '192.168.0.86'
    ipv6: '2001:123:4::6e'
  test-maxscale02.example.net:
    ipv4: '192.168.0.87'
    ipv6: '2001:123:4::6f'
maxscale_vip:
  test-maxscale.example.net:
    ipv4: '192.168.0.88'
    ipv4_subnet: '22'
    ipv6: '2001:123:4::70'

If you do not use ipv6, just skip the ipv6 keys as following:

galera_hosts:
  test-galera01.example.net:
    ipv4: '192.168.0.83'
  test-galera02.example.net:
    ipv4: '192.168.0.84'
  test-galera03.example.net:
... and so on ..

you need an array of trusted networks/hosts (a list of ipv4/ipv6 networks/hosts allowed to connect to Galera socket):

trusted_networks:
  - 192.168.0.1/24
  - 2001:123:4::70/64
  - 192.168.1.44
... and so on ...

Reference

Limitations

since the module it is still at an early stagem there are quite few limitations:

• important: MariaDB MaxScale reporisotry is not implemented (you need to install the RPM manually aotherwise the module will fail)
• important: not tested on ipv4 only
• important: changing MySQL root password is not yet supported. I will implement it ASAP. For the time being do not do it with puppetlabs/mysql or manually: it should be done in conjunction with Galera configurations (changing SST and Monitor password is possible).
• not tested yet on Ubuntu
• initial state transfer is supported only through Percona Xtrabackup (on average DBs I see no reason to use mysqldump and rsync since the donor would be unavailable during the transfer). I will investigate how mariabackup works.
• handle major/minor versions properly

Development

Feel free to make pull requests and/or open issues on my GitHub Repository

Release Notes/Contributors/Etc. Optional