8f54a80d24
The recent maas stonith resources, introduced to support stonith with pacemaker-remotes, included a hash of the combined url and api key in the resource name. But the charm only supports one stonith resource (single maas_url api key config options). Having the hash makes managing the resources more complicated espically when the url or api key change. So remove any existing resource (there is very unlikely to be one as the feature is only just out of preview state) and replace with a single resource called 'st-maas'. Change-Id: I053f1dc882eebfdef384cbbbfa7cabc82bce5f8b
Overview
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.
Usage
High availability can be configured in two mutually exclusive ways:
- virtual IP(s)
- DNS
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.
Configuration
This section covers common configuration options. See file config.yaml for
the full list of options, along with their descriptions and default values.
cluster_count
The 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.
Deployment
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
Actions
This section lists Juju actions supported by the charm. Actions allow specific operations to be performed on a per-unit basis.
pauseresumestatuscleanup
To display action descriptions run juju actions hacluster. If the charm is
not deployed then see file actions.yaml.
Bugs
Please report bugs on Launchpad.
For general charm questions refer to the OpenStack Charm Guide.