Juju Charm - HACluster
Go to file
Zuul 871f551e21 Merge "Get private-address for local unit from relation" 2023-10-03 15:20:00 +00:00
actions Safely delete node from ring 2021-06-25 07:38:18 -07:00
charmhelpers Add 2023.2 Bobcat support 2023-08-03 20:53:48 -04:00
files Fix standby node regex for check_crm 2022-05-02 19:17:36 -03:00
hooks Merge "Get private-address for local unit from relation" 2023-10-03 15:20:00 +00:00
lib Update tox.ini files from release-tools gold copy 2016-09-09 19:22:07 +00:00
templates Render corosync.conf file prior to pkg install 2022-03-16 08:13:49 -07:00
tests Add 2023.2 Bobcat support 2023-08-03 20:53:48 -04:00
unit_tests Get private-address for local unit from relation 2023-09-21 11:00:34 -03:00
.gitignore Update to classic charms to build using charmcraft in CI 2022-02-15 16:20:13 +00:00
.gitreview OpenDev Migration Patch 2019-04-19 19:30:01 +00:00
.project Refactoring to use openstack charm helpers. 2013-03-24 12:01:17 +00:00
.pydevproject Refactoring to use openstack charm helpers. 2013-03-24 12:01:17 +00:00
.stestr.conf Replace ostestr with stestr in testing framework. 2019-03-07 17:11:32 -05:00
.zuul.yaml Add 2023.2 Bobcat support 2023-08-03 20:53:48 -04:00
LICENSE Re-license charm as Apache-2.0 2016-06-28 12:12:40 +01:00
Makefile Port hacluster tests from Amulet to Zaza 2019-12-19 02:54:10 +00:00
README.md Trivial fix for README.md links 2022-08-15 09:51:35 +00:00
actions.yaml Fix typo in actions.yaml 2023-08-08 20:33:32 -04:00
bindep.txt Add bindep.txt 2022-10-03 16:34:04 -03:00
build-requirements.txt Update to classic charms to build using charmcraft in CI 2022-02-15 16:20:13 +00:00
charm-helpers-hooks.yaml Switch to render from charmhelpers 2022-06-01 16:16:17 +02:00
charmcraft.yaml Add 2023.2 Bobcat support 2023-08-03 20:53:48 -04:00
config.yaml Add option for no-quorum-policy 2021-06-25 10:18:14 +12:00
copyright Re-license charm as Apache-2.0 2016-06-28 12:12:40 +01:00
icon.svg Add icon and category 2014-04-11 12:22:46 +01:00
metadata.yaml Add docs key and point at Discourse 2023-08-22 17:13:18 -04:00
osci.yaml Use charmcraft 2.x to build 2023-08-10 15:32:35 -04:00
rename.sh Update to classic charms to build using charmcraft in CI 2022-02-15 16:20:13 +00:00
requirements.txt Update to classic charms to build using charmcraft in CI 2022-02-15 16:20:13 +00:00
setup.cfg fix coverage settings 2015-04-02 18:53:16 +01:00
test-requirements.txt Switch to render from charmhelpers 2022-06-01 16:16:17 +02:00
tox.ini Use charmcraft 2.x to build 2023-08-10 15:32:35 -04:00

README.md

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').

See OpenStack high availability in the OpenStack Charms Deployment Guide for a comprehensive treatment of HA with charmed OpenStack.

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.

  • pause
  • resume
  • status
  • cleanup
  • update-ring

To display action descriptions run juju actions hacluster. If the charm is not deployed then see file actions.yaml.

Presenting status information

Here are a few examples of how to present useful information with the status action and the jq utility.

  • Querying for online and standby parameter values:

    juju run-action --wait hacluster/leader status \
      --format json | jq '.[] | {(.UnitId):.results.result | fromjson \
      | .nodes | .[] | {unit_name: .name, online: .online, standby: .standby}}'
    

    output example

    {
      "hacluster/0": {
        "unit_name": "juju-a37bc0-3",
        "online": "true",
        "standby": "false"
      }
    }
    {
      "hacluster/0": {
        "unit_name": "juju-a37bc0-4",
        "online": "true",
        "standby": "false"
      }
    }
    {
      "hacluster/0": {
        "unit_name": "juju-a37bc0-5",
        "online": "true",
        "standby": "false"
      }
    }
    
  • Displaying cluster resource information:

    juju run-action --wait hacluster/leader status \
      --format json | jq '.[] | {(.UnitId):.results.result | fromjson \
      | .resources.groups}'
    

Bugs

Please report bugs on Launchpad.

For general charm questions refer to the OpenStack Charm Guide.