juju deploy cs:hacluster
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The hacluster charm provides high availability for OpenStack applications that lack native (built-in) HA functionality. The clustering solution is based on Corosync and Pacemaker.
It is a subordinate charm that works in conjunction with a principle charm that supports the 'hacluster' interface. The current list of such charms can be obtained from the Charm Store (the charms officially supported by the OpenStack Charms project are published by 'openstack-charmers').
Note: The hacluster charm is generally intended to be used with MAAS-based clouds.
High availability can be configured in two mutually exclusive ways:
- virtual IP(s)
The virtual IP method of implementing HA requires that all units of the clustered OpenStack application are on the same subnet.
The DNS method of implementing HA requires that MAAS is used as the backing cloud. The clustered nodes must have static or "reserved" IP addresses registered in MAAS. If using a version of MAAS earlier than 2.3 the DNS hostname(s) should be pre-registered in MAAS before use with DNS HA.
This section covers common configuration options. See file
the full list of options, along with their descriptions and default values.
cluster_count option sets the number of hacluster units required to form
the principle application cluster (the default is 3). It is best practice to
provide a value explicitly as doing so ensures that the hacluster charm will
wait until all relations are made to the principle application before building
the Corosync/Pacemaker cluster, thereby avoiding a race condition.
At deploy time an application name should be set, and be based on the principle charm name (for organisational purposes):
juju deploy hacluster <principle-charm-name>-hacluster
A relation is then added between the hacluster application and the principle application.
In the below example the VIP approach is taken. These commands will deploy a three-node Keystone HA cluster, with a VIP of 10.246.114.11. Each will reside in a container on existing machines 0, 1, and 2:
juju deploy -n 3 --to lxd:0,lxd:1,lxd:2 --config vip=10.246.114.11 keystone juju deploy --config cluster_count=3 hacluster keystone-hacluster juju add-relation keystone-hacluster:ha keystone:ha
This section lists Juju actions supported by the charm. Actions allow specific operations to be performed on a per-unit basis.
To display action descriptions run
juju actions hacluster. If the charm is
not deployed then see file
Please report bugs on Launchpad.
For general charm questions refer to the OpenStack Charm Guide.