External MariaDB

updated: 2020-06-17 15:08

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 (recommended)¶

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

Within your inventory file, just add the hostname of the load balancer within the mariadb group, described as below:

Change the following

[mariadb:children]
control

so that it looks like below:

[mariadb]
myexternalmariadbloadbalancer.com

Define database_address within /etc/kolla/globals.yml

database_address: myexternalloadbalancer.com

Please note that if enable_external_mariadb_load_balancer is set to “no” - default, the external DB load balancer will need to be accessible from all nodes within your deployment, which might connect to it.

Using an external MariaDB cluster:¶

Then, you will need to adjust your inventory file:

Change the following

[mariadb:children]
control

so that it looks like below:

[mariadb]
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 and resolvable from all the hosts within the [haproxy:children] group of your inventory (defaults to [network]).

In addition to that, you also need to set the following within /etc/kolla/globals.yml:

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 field within /etc/kolla/passwords.yml

database_password: mySuperSecurePassword

In case your username is other than root, you will need to also set it, within /etc/kolla/globals.yml

database_username: "privillegeduser"

Using preconfigured databases / users:¶

The first step you need to take is the following:

Within /etc/kolla/globals.yml, set the following:

use_preconfigured_databases: "yes"

Note

Please note that when the use_preconfigured_databases flag is set to "yes", you need to have the log_bin_trust_function_creators mysql variable set to 1 by your 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 within /etc/kolla/globals.yml, as illustrated by the example below:

keystone_database_user: preconfigureduser1
nova_database_user: preconfigureduser2

You will need to also set the passwords for all databases within /etc/kolla/passwords.yml

However, fortunately, using a common user across all databases is also 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:

Within /etc/kolla/globals.yml, add the following:

use_common_mariadb_user: "yes"

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

database_user: mycommondatabaseuser

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

updated: 2020-06-17 15:08

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