Percona XtraDB Cluster

master

Role which installs and configures Percona XtraDB Cluster.

Deploy example (do not copy blindly!)

    - role: percona-cluster
      percona_cluster_version: "5.7"
      percona_cluster_root_password: "strong_password_from_vault"
      percona_cluster_general:
        datadir: /var/lib/mysql
        bind_address: '0.0.0.0'
        innodb_large_prefix: false
        expire_log_days: 8
      percona_cluster_global_params:
        max_connections: 1000
        character_set_server: utf8
      percona_cluster_wsrep:
        - name: node1
          primary: true
          server_id: 'some_unique_id'
          wsrep_cluster_address: "gcomm://1.1.1.1,2.2.2.2,3.3.3.3"
          wsrep_cluster_name: 'test-cluster'
          wsrep_node_address: "1.2.3.4"
          wsrep_node_name: 'some-node'
          wsrep_provider: "/usr/lib/libgalera_smm.so"
          wsrep_sst_method: "xtrabackup-v2"
          wsrep_slave_threads: '1'
          wsrep_provider_options: ''
          sst_username: 'some-username'
          sst_password: 'another_strong_password_from_vault'
          monitoring_username: 'netdata'
          monitoring_password: 'and_another_strong_password_from_vault'
          custom_node_params:
            query_cache_limit: 16M
            query_cache_size: 512M
      percona_cluster_wsrep_notify:
        enabled: true
        script_path: '/usr/local/sbin/custom.wsrep_notify'
        mail_addr: 'project-name-here@osshelp.pagerduty.com'

About available parameters

Main params

Param	Description
percona_cluster_version	version of Percona-cluster to install
percona_cluster_root_password	root password for MySQL. Make sure it is taken from vault

percona_cluster_general

These params are for setting up general MySQL params:

Param	Description
datadir	MySQL data directory
bind_address	an IP-address to bind to
innodb_buffer_pool_size	InnoDB buffer pool size
innodb_large_prefix	when set to "true", index key prefixes longer than 767 bytes (up to 3072 bytes) are allowed for InnoDB
expire_log_days	number of days to keep binary logs
percona_cluster_global_params	global parameters for MySQL main config

percona_cluster_wsrep

Most of these params are for setting up wsrep, check our article for more details. But there are some extra:

Param	Description
server_id	unique id, needed for correct clusterization
primary	if set to "true" the node will be used for sst-user and monitoring-user creation
monitoring_username, monitoring_password	credentials for monitoring access (netdata)
custom_node_params	custom parameters for percona-cluster node

Configuration files for each node is generated in the /etc/mysql/conf-avalaible directory. To enable it, use lxhelper profile section, for example:

    profiles:
      db1:
        mysql:
          enable-cfg:
            - wsrep-db1.cnf

percona_cluster_wsrep_notify

Params prior to our script for checking cluster status. See this article for info. Make sure to use the correct address in mail_addr variable (Pagerduty address), or we won't receive those alerts when cluster breaks.

Cluster bootstraping

Not supported by the role, and there is no assurance that it will be implemented. You need to bootstrap manually.

Useful links

• Official documentation
• Our article about cluster setup
• Our article about monitoring script (wsrep_notify)

TODO

• Check the role in various builds
• Improve tests (separate testing of different versions)