galera cluster #1

Supports: trusty


Galera Cluster provides an active/active MySQL compatible alternative implemented using the Galera synchronous replication library.

This charm is based on the Percona Cluster charm by James Page


Galera Cluster is a high availability and high scalability solution for MySQL clustering. Galera Cluster integrates MySQL 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 Galera 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 Galera Cluster.


The following configuration parameters are required:

  • root-password - Due to the multi-master nature of Galera Cluster, the root-password needs to be specified in advance so that all nodes have the same root password.

  • sst-password - This password is used as a shared secret between nodes when performing whole-database transfers between nodes during node deployment.

Proxy Configuration

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 as the charm installs packages directly from the Galera repositories. If you are using squid-deb-proxy, follow the steps below:

echo "" | sudo tee /etc/squid-deb-proxy/mirror-dstdomain.acl.d/40-galera
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 > galera.yaml << EOF
    root-password: my-root-password
    sst-password: my-sst-password

Once you have created this file, you can deploy the first seed unit:

juju deploy --config galera.yaml cs:~codership/galera-cluster

Once this node is full operational, you can add extra units one at a time to the deployment:

juju add-unit galera-cluster

A minimum cluster size of three units is recommended.

In order to access the cluster, you can use the hacluster charm in multicast-capable deployments to provide a single IP address:

juju set galera-cluster vip=
juju deploy hacluster
juju add-relation hacluster galera-cluster

Clients can then access using the vip provided. This vip will be passed to related services:

juju add-relation keystone galera-cluster


Note that Galera Cluster is not a 'scale-out' MySQL solution; reads and writes are channeled 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.


(string) The IP address and netmask of the 'access' network (e.g., . This network will be used for access to database services.
(string) How much data do you want to keep in memory in the DB. This will be used to tune settings in the database server appropriately. Suffix this value with 'K','M','G', or 'T' to get the relevant kilo/mega/etc. bytes. If suffixed with %, one will get that percentage of RAM devoted to dataset.
(string) Default network interface on which HA cluster will bind to communication with the other members of the HA Cluster.
(int) Default multicast port number that will be used to communicate between HA Cluster nodes.
(boolean) Turns on innodb_file_per_table option, which will make MySQL put each InnoDB table into separate .idb file. Existing InnoDB tables will remain in ibdata1 file - full dump/import is needed to get rid of large ibdata1 file
(int) Maximum connections to allow. -1 means use the server's compiled in default.
(boolean) If True enables IPv6 support. The charm will expect network interfaces to be configured with an IPv6 address. If set to False (default) IPv4 is expected. . NOTE: these charms do not currently support IPv6 privacy extension. In order for this charm to function correctly, the privacy extension must be disabled and a non-temporary address must be configured/available on your network interface.
(string) Root password for MySQL access; must be configured pre-deployment for Active-Active clusters.
(string) Additional package install location
(string) Package install location for Galera Cluster (defaults to distro for >= 14.04)
(string) key for source-galera repository
(string) Re-sync account password for new cluster nodes; must be configured pre-deployment for Active-Active clusters.
(string) Virtual IP to use to front Galera Cluster in active/active HA configuration
(int) Netmask that will be used for the Virtual IP
(string) Network interface on which to place the Virtual IP