kolla-ansible/ansible/roles/mariadb/tasks/lookup_cluster.yml
Michal Arbet 09b3c6ca07 Refactor mariadb to support shards
Kolla-ansible is currently installing mariadb
cluster on hosts defined in group['mariadb']
and render haproxy configuration for this hosts.

This is not enough if user want to have several
service databases in several mariadb clusters (shards).

Spread service databases to multiple clusters (shards)
is usefull especially for databases with high load
(neutron,nova).

How it works ?

It works exactly same as now, but group reference 'mariadb'
is now used as group where all mariadb clusters (shards)
are located, and mariadb clusters are installed to
dynamic groups created by group_by and host variable
'mariadb_shard_id'.

It also adding special user 'shard_X' which will be used
for creating users and databases, but only if haproxy
is not used as load-balance solution.

This patch will not affect user which has all databases
on same db cluster on hosts in group 'mariadb', host
variable 'mariadb_shard_id' is set to 0 if not defined.

Mariadb's task in loadbalancer.yml (haproxy) is configuring
mariadb default shard hosts as haproxy backends. If mariadb
role is used to install several clusters (shards), only
default one is loadbalanced via haproxy.

Mariadb's backup is working only for default shard (cluster)
when using haproxy as mariadb loadbalancer, if proxysql
is used, all shards are backuped.

After this patch will be merged, there will be way for proxysql
patches which will implement L7 SQL balancing based on
users and schemas.

Example of inventory:

[mariadb]
server1
server2
server3 mariadb_shard_id=1
server4 mariadb_shard_id=1
server5 mariadb_shard_id=2
server6 mariadb_shard_id=3

Extra:
wait_for_loadbalancer is removed instead of modified as its role
is served by check already. The relevant refactor is applied as
well.

Change-Id: I933067f22ecabc03247ea42baf04f19100dffd08
Co-Authored-By: Radosław Piliszek <radoslaw.piliszek@gmail.com>
2021-04-07 23:19:42 +02:00

80 lines
3.1 KiB
YAML

---
- name: Create MariaDB volume
become: true
kolla_docker:
action: "create_volume"
common_options: "{{ docker_common_options }}"
name: "mariadb"
register: mariadb_volume
- name: Divide hosts by their MariaDB volume availability
group_by:
key: "{{ mariadb_shard_group }}_had_volume_{{ mariadb_volume is not changed }}"
changed_when: false
- name: Establish whether the cluster has already existed
set_fact:
mariadb_cluster_exists: "{{ groups[mariadb_shard_group + '_had_volume_True'] is defined }}"
- block:
- name: Check MariaDB service port liveness
wait_for:
host: "{{ api_interface_address }}"
port: "{{ mariadb_port }}"
connect_timeout: 1
timeout: 10
search_regex: "MariaDB"
register: check_mariadb_port_liveness
ignore_errors: yes
- name: Divide hosts by their MariaDB service port liveness
group_by:
key: "{{ mariadb_shard_group }}_port_alive_{{ check_mariadb_port_liveness is success }}"
changed_when: false
- name: Fail on existing but stopped cluster
fail:
msg: MariaDB cluster exists but is stopped. Please start it using kolla-ansible mariadb_recovery
when:
# NOTE(yoctozepto): we allow single-node cluster to start
- groups[mariadb_shard_group] | length > 1
- mariadb_cluster_exists
- groups[mariadb_shard_group + '_port_alive_True'] is not defined
- block:
- name: Check MariaDB service WSREP sync status
become: true
command: >-
docker exec {{ mariadb_service.container_name }}
mysql -uroot -p{{ database_password }}
--silent --skip-column-names
-e 'SHOW STATUS LIKE "wsrep_local_state_comment"'
changed_when: false
register: check_mariadb_sync_status
no_log: true
# NOTE(yoctozepto): this is extracted separately to properly escape
# the TAB character which likes to go wrong due to interaction between
# Python/Ansible/Jinja2/YAML, the way below works
- name: Extract MariaDB service WSREP sync status
set_fact:
mariadb_sync_status: "{{ check_mariadb_sync_status.stdout.split('\t')[1] }}"
when:
- groups[mariadb_shard_group + '_port_alive_True'] is defined
- inventory_hostname in groups[mariadb_shard_group + '_port_alive_True']
- name: Divide hosts by their MariaDB service WSREP sync status
group_by:
key: "{{ mariadb_shard_group }}_sync_status_{{ mariadb_sync_status | default('NA') }}"
changed_when: false
- name: Fail when MariaDB services are not synced across the whole cluster
fail:
msg: MariaDB cluster is not synced. Please wait for WSREP sync before proceeding.
when:
- groups[mariadb_shard_group + '_port_alive_True'] is defined
- groups[mariadb_shard_group + '_sync_status_Synced'] is not defined or
groups[mariadb_shard_group + '_port_alive_True'] | sort != groups[mariadb_shard_group + '_sync_status_Synced'] | sort
when: not mariadb_recover | default(False)