From 0e87b4dcc01b7d1b6ab4b756c0e1defefecb6073 Mon Sep 17 00:00:00 2001 From: Peter Matulis Date: Fri, 29 May 2020 13:42:11 -0400 Subject: [PATCH] Apply HA section template to README Change-Id: I1d9d7811c1ba67e253517f69ad624d49b06efec0 --- README.md | 38 ++++++++++---------------------------- 1 file changed, 10 insertions(+), 28 deletions(-) diff --git a/README.md b/README.md index 15d65aaf..2892623e 100644 --- a/README.md +++ b/README.md @@ -27,37 +27,17 @@ charm: juju set neutron-api vip= juju add-relation neutron-hacluster neutron-api -## HA/Clustering +## High availability + +When more than one unit is deployed with the [hacluster][hacluster-charm] +application the charm will bring up an HA active/active cluster. There are two mutually exclusive high availability options: using virtual IP(s) -or DNS. In both cases, a relationship to hacluster is required which provides -the corosync back end HA functionality. +or DNS. In both cases the hacluster subordinate charm is used to provide the +Corosync and Pacemaker backend HA functionality. -To use virtual IP(s) the clustered nodes must be on the same subnet such that -the VIP is a valid IP on the subnet for one of the node's interfaces and each -node has an interface in said subnet. The VIP becomes a highly-available API -endpoint. - -At a minimum, the config option 'vip' must be set in order to use virtual IP -HA. If multiple networks are being used, a VIP should be provided for each -network, separated by spaces. Optionally, vip_iface or vip_cidr may be -specified. - -To use DNS high availability there are several prerequisites. However, DNS HA -does not require the clustered nodes to be on the same subnet. Currently the -DNS HA feature is only available for MAAS 2.0 or greater environments. MAAS 2.0 -requires Juju 2.0 or greater. The clustered nodes must have static or -"reserved" IP addresses registered in MAAS. The DNS hostname(s) must be -pre-registered in MAAS before use with DNS HA. - -At a minimum, the config option 'dns-ha' must be set to true and at least one -of 'os-public-hostname', 'os-internal-hostname' or 'os-internal-hostname' must -be set in order to use DNS HA. One or more of the above hostnames may be set. - -The charm will throw an exception in the following circumstances: If neither -'vip' nor 'dns-ha' is set and the charm is related to hacluster If both 'vip' -and 'dns-ha' are set as they are mutually exclusive. If 'dns-ha' is set and -none of the os-{admin,internal,public}-hostname(s) are set +See [OpenStack high availability][cdg-ha-apps] in the [OpenStack Charms +Deployment Guide][cdg] for details. # Restrictions @@ -223,3 +203,5 @@ For general charm questions refer to the OpenStack [Charm Guide][cg]. [cdg]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide [cdg-appendix-n]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-policy-overrides.html [lp-bugs-charm-neutron-api]: https://bugs.launchpad.net/charm-neutron-api/+filebug +[hacluster-charm]: https://jaas.ai/hacluster +[cdg-ha-apps]: https://docs.openstack.org/project-deploy-guide/charm-deployment-guide/latest/app-ha.html#ha-applications