[ClusterLabs] Resource(s) for mysql+galera cluster

[Michele Baldessari]

Hi,

On Tue, Dec 14, 2021 at 03:09:56PM +0000, lejeczek via Users wrote:
> I failed to find any good or any for that matter info, on present-day
> mariadb/mysql galera cluster setups - would you know of any docs which
> discuss such scenario comprehensively?
> I see there among resources are 'mariadb' and 'galera' but which one to use
> I'm still confused.

in the deployment of OpenStack via TripleO[1] we set up galera in
multi-master mode using the galera resource agent[2] (it runs in bundles
aka containers in our specific case, but that is tangential).

Here is an example of the pcs commands we use to start it (these are
a bit old, things might have changed since):

pcs property set --node controller-1 galera-role=true
pcs resource bundle create galera-bundle container docker image=192.168.24.1:8787/rhosp13/openstack-mariadb:pcmklatest replicas=3 masters=3 options="--user=root --log-driver=journald -e KOLLA_CONFIG_STRATEGY=COPY_ALWAYS" run-command="/bin/bash /usr/local/bin/kolla_start" network=host storage-map id=mysql-cfg-files source-dir=/var/lib/kolla/config_files/mysql.json target-dir=/var/lib/kolla/config_files/config.json options=ro storage-map id=mysql-cfg-data source-dir=/var/lib/config-data/puppet-generated/mysql/ target-dir=/var/lib/kolla/config_files/src options=ro storage-map id=mysql-hosts source-dir=/etc/hosts target-dir=/etc/hosts options=ro storage-map id=mysql-localtime source-dir=/etc/localtime target-dir=/etc/localtime options=ro storage-map id=mysql-lib source-dir=/var/lib/mysql target-dir=/var/lib/mysql options=rw storage-map id=mysql-log-mariadb source-dir=/var/log/mariadb target-dir=/var/log/mariadb options=rw storage-map id=mysql-log source-dir=/var/log/containers/mysql target-dir=/var/log/mysql options=rw storage-map id=mysql-dev-log source-dir=/dev/log target-dir=/dev/log options=rw network control-port=3123 --disabled

pcs constraint location galera-bundle rule resource-discovery=exclusive score=0 galera-role eq true

pcs resource create galera ocf:heartbeat:galera log='/var/log/mysql/mysqld.log' additional_parameters='--open-files-limit=16384' enable_creation=true wsrep_cluster_address='gcomm://controller-0.internalapi.localdomain,controller-1.internalapi.localdomain,controller-2.internalapi.localdomain' cluster_host_map='controller-0:controller-0.internalapi.localdomain;controller-1:controller-1.internalapi.localdomain;controller-2:controller-2.internalapi.localdomain' meta master-max=3 ordered=true container-attribute-target=host op promote timeout=300s on-fail=block bundle galera-bundle

I don't think we have any docs discussing tradeoffs around this setup,
but maybe this is a start. If you want multi-master galera then you can
do it with the galera RA. If you need to look at more recent configs
check out [3] (Click on a job and the logs and you can check something
like [4] for the full pcs config)

hth,
Michele

[1] https://docs.openstack.org/tripleo-docs/latest/
[2] https://github.com/ClusterLabs/resource-agents/blob/master/heartbeat/galera.in
[3] https://review.rdoproject.org/zuul/builds?job_name=periodic-tripleo-ci-centos-8-ovb-3ctlr_1comp-featureset035-master
[4] https://logserver.rdoproject.org/openstack-periodic-integration-main/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-8-ovb-3ctlr_1comp-featureset035-master/31594c2/logs/overcloud-controller-0/var/log/extra/pcs.txt.gz
-- 
Michele Baldessari            <michele at acksyn.org>
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