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 firstname.lastname@example.org
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.
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 releases.galeracluster.com
as the charm installs packages directly from the Galera repositories. If you
are using squid-deb-proxy, follow the steps below:
echo "releases.galeracluster.com" | 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
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
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=10.0.3.200
juju deploy hacluster
juju add-relation hacluster galera-cluster
Clients can then access using the vip provided. This vip will be passed to
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.