Percona XtraDB Cluster provides an active/active MySQL
compatible alternative implemented using the Galera
synchronous replication extensions.
Percona XtraDB Cluster is a high availability and high scalability solution for
MySQL clustering. Percona XtraDB Cluster integrates Percona Server with the
Galera library of MySQL high availability solutions in a single product package
which enables you to create a cost-effective MySQL cluster.
This charm deploys Percona XtraDB Cluster onto Ubuntu.
WARNING: Its critical that you follow the bootstrap process detailed in this
document in order to end up with a running Active/Active Percona Cluster.
If you are deploying this charm on MAAS or in an environment without direct
access to the internet, you will need to allow access to repo.percona.com
as the charm installs packages direct from the Percona respositories. If you
are using squid-deb-proxy, follow the steps below:
echo "repo.percona.com" | sudo tee /etc/squid-deb-proxy/mirror-dstdomain.acl.d/40-percona
sudo service squid-deb-proxy restart
The first service unit deployed acts as the seed node for the rest of the
cluster; in order for the cluster to function correctly, the same MySQL passwords
must be used across all nodes:
cat > percona.yaml << EOF
Once you have created this file, you can deploy the first seed unit:
juju deploy --config percona.yaml percona-cluster
Once this node is full operational, you can add extra units one at a time to the
juju add-unit percona-cluster
A minimium cluster size of three units is recommended.
There are two mutually exclusive high availability options: using virtual
IP(s) or DNS. In both cases, a relationship to hacluster is required which
provides the corosync back end HA functionality.
To use virtual IP(s) the clustered nodes must be on the same subnet such that
the VIP is a valid IP on the subnet for one of the node's interfaces and each
node has an interface in said subnet. The VIP becomes a highly-available API
At a minimum, the config option 'vip' must be set in order to use virtual IP
HA. If multiple networks are being used, a VIP should be provided for each
network, separated by spaces. Optionally, vip_iface or vip_cidr may be
To use DNS high availability there are several prerequisites. However, DNS HA
does not require the clustered nodes to be on the same subnet.
Currently the DNS HA feature is only available for MAAS 2.0 or greater
environments. MAAS 2.0 requires Juju 2.0 or greater. The clustered nodes must
have static or "reserved" IP addresses registered in MAAS. The DNS hostname(s)
must be pre-registered in MAAS before use with DNS HA.
At a minimum, the config option 'dns-ha' must be set to true and
'os-access-hostname' must be set in order to use DNS HA.
The charm will throw an exception in the following circumstances:
If neither 'vip' nor 'dns-ha' is set and the charm is related to hacluster
If both 'vip' and 'dns-ha' are set as they are mutually exclusive
If 'dns-ha' is set and os-access-hostname is not set
This charm supports the use of Juju Network Spaces, allowing the charm to be bound to network space configurations managed directly by Juju. This is only supported with Juju 2.0 and above.
You can ensure that database connections are bound to a specific network space by binding the appropriate interfaces:
juju deploy percona-cluster --bind "shared-db=internal-space"
alternatively these can also be provided as part of a juju native bundle configuration:
NOTE: Spaces must be configured in the underlying provider prior to attempting to use them.
NOTE: Existing deployments using the access-network configuration option will continue to function; this option is preferred over any network space binding provided if set.
Note that Percona XtraDB Cluster is not a 'scale-out' MySQL solution; reads
and writes are channelled through a single service unit and synchronously
replicated to other nodes in the cluster; reads/writes are as slow as the
slowest node you have in your deployment.