kolla-ansible/doc/source/reference/external-mariadb-guide.rst

External MariaDB

Sometimes, for various reasons (Redundancy, organisational policies, etc.), it might be necessary to use an externally managed database. This use case can be achieved by simply taking some extra steps:

Requirements

• An existing MariaDB cluster / server, reachable from all of your nodes.
• If you choose to use preconfigured databases and users (use_preconfigured_databases is set to "yes"), databases and user accounts for all enabled services should exist on the database.
• If you choose not to use preconfigured databases and users (use_preconfigured_databases is set to "no"), root access to the database must be available in order to configure databases and user accounts for all enabled services.

Enabling External MariaDB support

In order to enable external mariadb support, you will first need to disable mariadb deployment, by ensuring the following line exists within /etc/kolla/globals.yml :

enable_mariadb: "no"

There are two ways in which you can use external MariaDB: * Using an already load-balanced MariaDB address * Using an external MariaDB cluster

Using an already load-balanced MariaDB address (recommended)

If your external database already has a load balancer, you will need to do the following:

1. Edit the inventory file, change control to the hostname of the load balancer within the mariadb group as below:

   [mariadb:children]
   myexternalmariadbloadbalancer.com

2. Define database_address in /etc/kolla/globals.yml file:

   database_address: myexternalloadbalancer.com

Note

If enable_external_mariadb_load_balancer is set to no (default), the external DB load balancer should be accessible from all nodes during your deployment.

Using an external MariaDB cluster

Using this way, you need to adjust the inventory file:

[mariadb:children]
myexternaldbserver1.com
myexternaldbserver2.com
myexternaldbserver3.com

If you choose to use haproxy for load balancing between the members of the cluster, every node within this group needs to be resolvable and reachable from all the hosts within the [haproxy:children] group of your inventory (defaults to [network]).

In addition, configure the /etc/kolla/globals.yml file according to the following configuration:

enable_external_mariadb_load_balancer: yes

Using External MariaDB with a privileged user

In case your MariaDB user is root, just leave everything as it is within globals.yml (Except the internal mariadb deployment, which should be disabled), and set the database_password in /etc/kolla/passwords.yml file:

database_password: mySuperSecurePassword

If the MariaDB username is not root, set database_username in /etc/kolla/globals.yml file:

database_username: "privillegeduser"

Using preconfigured databases / users:

The first step you need to take is to set use_preconfigured_databases to yes in the /etc/kolla/globals.yml file:

use_preconfigured_databases: "yes"

Note

when the use_preconfigured_databases flag is set to "yes", you need to make sure the mysql variable log_bin_trust_function_creators set to 1 by the database administrator before running the upgrade command.

Using External MariaDB with separated, preconfigured users and databases

In order to achieve this, you will need to define the user names in the /etc/kolla/globals.yml file, as illustrated by the example below:

keystone_database_user: preconfigureduser1
nova_database_user: preconfigureduser2

Also, you will need to set the passwords for all databases in the /etc/kolla/passwords.yml file

However, fortunately, using a common user across all databases is possible.

Using External MariaDB with a common user across databases

In order to use a common, preconfigured user across all databases, all you need to do is the following steps:

1. Edit the /etc/kolla/globals.yml file, add the following:

   use_common_mariadb_user: "yes"

2. Set the database_user within /etc/kolla/globals.yml to the one provided to you:

   database_user: mycommondatabaseuser

3. Set the common password for all components within /etc/kolla/passwords.yml`. In order to achieve that you could use the following command:

   sed -i -r -e 's/([a-z_]{0,}database_password:+)(.*)$/\1 mycommonpass/gi' /etc/kolla/passwords.yml