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Backup and Restore OpenStack Service Databases

Kolla Ansible provides a utility to create copies of all OpenStack service databases, called mariadb_backup. In this section, we explain how to use Kolla Ansible's builtin function to create database backups of a Private Cloud's OpenStack services.

Prerequisites

Before proceeding with this guide, a Kolla Ansible environment needs to be prepared. For information about preparing a Kolla Ansible environment, see How to Prepare and Use Kolla Ansible. Once the environment is prepared, come back to this guide to learn how to create database backups of OpenStack services.

How to Create OpenStack Service Database Backups

The following instruction must be performed from the folder in which you have prepared Kolla Ansible. This section first provides the command syntax, then follows up with an example of the command's execution and output. Note that Kolla Ansible has no way to schedule backups.

Command Syntax for Full Database Backups

The command to perform a full backup of all databases using Kolla Ansible is...:

kolla-ansible -i <inventory> mariadb_backup

...where <inventory> is the path to the Kolla Ansible inventory file.

Command Syntax for Incremental Database Backups

The command to perform an incremental backup of all databases using Kolla Ansible is...:

kolla-ansible -i <inventory> mariadb_backup --incremental

...where <inventory> is the path to the Kolla Ansible inventory file.

Path to the Kolla Ansible Inventory File

The Kolla Ansible inventory file is located across all control plane nodes as:

/etc/fm-deploy/kolla-ansible-inventory

Command Usage Example for a Full Database Backup

From the host that has Kolla Ansible prepared, the following command is executed:

kolla-ansible -i /etc/fm-deploy/kolla-ansible-inventory mariadb_backup

Truncated output of the above command:

# kolla-ansible -i /etc/fm-deploy/kolla-ansible-inventory mariadb_backup
Backup MariaDB databases : ansible-playbook -i /etc/fm-deploy/kolla-ansible-inventory -e @/etc/kolla/globals.yml -e @/etc/kolla/passwords.yml -e CONFIG_DIR=/etc/kolla -e kolla_action=backup -e mariadb_backup_type=full /opt/kolla-ansible/.venv/share/kolla-ansible/ansible/mariadb_backup.yml

[...previous output truncated...]

TASK [mariadb : Taking full database backup via Mariabackup] **************************************************************************************************
skipping: [focused-capybara]
skipping: [lovely-ladybug]
[WARNING]: The value False (type bool) in a string field was converted to 'False' (type string). If this does not look like what you expect, quote the entire
value to ensure it does not change.
changed: [relaxed-flamingo]

PLAY RECAP ****************************************************************************************************************************************************
focused-capybara : ok=2 changed=0 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
lovely-ladybug : ok=2 changed=0 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
relaxed-flamingo : ok=3 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0

The task [mariadb : Taking full database backup via Mariabackup] is where a backup of all OpenStack service databases is created. Kolla Ansible creates a Docker volume called mariadb_backup to store the database copies. Previous backups made using this method are not overwritten. The host under this task that reports a change (example: changed=1) is where the Docker volume storing the databases is created.

Note! -- For this example, since the Docker volume was created on another host, the remaining instruction in this guide must be performed from that host. If Kolla Ansible creates mariadb_backup on another host, you must SSH into that host as root to continue this process.

Command Usage Example for an Incremental Database Backup

Note! -- Incremental backups can only be made if a full backup has been made prior, otherwise the following command will result in an error.

From the host that has Kolla Ansible prepared, the following command is executed:

kolla-ansible -i /etc/fm-deploy/kolla-ansible-inventory mariadb_backup \
--incremental

Truncated output of the above command:

# kolla-ansible -i /etc/fm-deploy/kolla-ansible-inventory mariadb_backup --incremental
Backup MariaDB databases : ansible-playbook -i /etc/fm-deploy/kolla-ansible-inventory -e @/etc/kolla/globals.yml -e @/etc/kolla/passwords.yml -e CONFIG_DIR=/etc/kolla -e kolla_action=backup -e mariadb_backup_type=incremental /opt/kolla-ansible/.venv/share/kolla-ansible/ansible/mariadb_backup.yml

[...previous output truncated...]

TASK [mariadb : include_tasks] ****************************************************************************************************************************************************************
included: /opt/kolla-ansible/.venv/share/kolla-ansible/ansible/roles/mariadb/tasks/backup.yml for relaxed-flamingo, focused-capybara, lovely-ladybug

TASK [mariadb : Taking incremental database backup via Mariabackup] ***************************************************************************************************************************
skipping: [focused-capybara]
skipping: [lovely-ladybug]
[WARNING]: The value False (type bool) in a string field was converted to 'False' (type string). If this does not look like what you expect, quote the entire value to ensure it does not
change.
changed: [relaxed-flamingo]

PLAY RECAP ************************************************************************************************************************************************************************************
focused-capybara : ok=2 changed=0 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
lovely-ladybug : ok=2 changed=0 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
relaxed-flamingo : ok=3 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0

The task [mariadb : Taking incremental database backup via Mariabackup] is where an incremental backup of all OpenStack service databases is created. Kolla Ansible creates a Docker volume called mariadb_backup to store the database copies. Previous backups made using this method are not overwritten. The host under this task that reports a change (example: changed=1) is where the Docker volume storing the databases is created.

Note! -- For this example, since the Docker volume was created on another host, the remaining instruction in this guide must be performed from that host. If Kolla Ansible creates mariadb_backup on another host, you must SSH into that host as root to continue this process.

How to Restore a Private Cloud's OpenStack Service Databases

This section explains how to restore both full and incremental database backups created using Kolla Ansible's mariadb_backup function.

Full Database Restoration Steps

Follow these steps to learn how to restore full OpenStack service databases created using Kolla Ansible's mariadb_backup function.

Full Restoration: Create Temporary Docker Container

In this section, we create a temporary Docker container called dbrestore. This container is created with the same volumes as the mariadb Docker container. The mariadb_backup Docker volume is mounted as /backup in this container. Finally, the container is created using the kolla/centos-binary-mariadb:victoria Docker image available from Docker Hub with a Bash shell.

Create the temporary Docker container called dbrestore using:

docker run --rm -it --volumes-from mariadb --name dbrestore \
--volume mariadb_backup:/backup \
kolla/centos-binary-mariadb:victoria \
/bin/bash

Once you run the above Docker command, your terminal should appear this way:

()[mysql@06ab93fb83a3 /]$

Full Restoration: Prepare Backup Directory

Caution! -- Be careful when using commands. The following commands make use of the rm command which deletes files.

Next, the backup data must be prepared before it can be copied into place.

This example uses a full MariaDB backup called mysqlbackup-08-12-2021-1638999340.qp.xbc.xbs.gz.

To prepare the backup data, in the Docker container, run:

cd /backup
rm -rf /backup/restore
mkdir -p /backup/restore/full
gunzip mysqlbackup-08-12-2021-1638999340.qp.xbc.xbs.gz
mbstream -x -C /backup/restore/full/ < mysqlbackup-08-12-2021-1638999340.qp.xbc.xbs
mariabackup --prepare --target-dir /backup/restore/full

Load another shell session for the node in which you are working and stop the MariaDB Docker container:

docker stop mariadb

Navigate back to the Docker container and run:

rm -rf /var/lib/mysql/*
rm -rf /var/lib/mysql/\.[^\.]*
mariabackup --copy-back --target-dir /backup/restore/full

Next, navigate back to the other shell and start the MariaDB Docker container:

docker start mariadb

Examine MariaDB's logs to confirm the Galera cluster has synchronized:

# tail -1 /var/log/kolla/mariadb/mariadb.log
2021-12-08 22:27:39 2 [Note] WSREP: Synchronized with group, ready for
connections

Incremental Database Restoration Steps

Follow these steps to learn how to restore an incremental OpenStack service database backup created using Kolla Ansible's mariadb_backup function.

Incremental Restoration: Create Temporary Docker Container

In this section, we create a temporary Docker container called dbrestore. This container is created with the same volumes as the mariadb Docker container. The mariadb_backup Docker volume is mounted as /backup in this container. Finally, the container is created using the kolla/centos-binary-mariadb:victoria Docker image available from Docker Hub with a Bash shell.

Create the temporary Docker container called dbrestore using:

docker run --rm -it \
--volumes-from mariadb \
--name dbrestore \
--volume mariadb_backup:/backup \
kolla/centos-binary-mariadb:victoria \
/bin/bash

Once you run the above Docker command, your terminal should appear this way:

()[mysql@06ab93fb83a3 /]$

Incremental Restoration: Prepare Backup Directory

Caution! -- Be careful when using commands. The following commands make use of the rm command which deletes files.

This section assumes a full and incremental backup have been created. Note that your full and incremental backup file names will differ from this example.

Next, we must prepare the backup data before it can be copied into place.

In the Docker container, run:

cd /backup/
rm -rf /backup/restore
mkdir -p /backup/restore/full
mkdir -p /backup/restore/incremental
gunzip mysqlbackup-10-12-2021-1639166052.qp.xbc.xbs.gz
gunzip incremental-20-mysqlbackup-10-12-2021-1639169695.qp.xbc.xbs.gz
mbstream -x -C /backup/restore/full/ < mysqlbackup-10-12-2021-1639166052.qp.xbc.xbs
mbstream -x -C /backup/restore/incremental/ < incremental-20-mysqlbackup-10-12-2021-1639169695.qp.xbc.xbs
mariabackup --prepare --target-dir=/backup/restore/full/
mariabackup --prepare --target-dir=/backup/restore/full/ --incremental-dir=/backup/restore/incremental/

Load another shell session for the node in which you are working and stop the MariaDB Docker container:

docker stop mariadb

Navigate back to the Docker container and run:

rm -rf /var/lib/mysql/*
rm -rf /var/lib/mysql/\.[^/.]*
mariabackup --copy-back --target-dir /backup/restore/full/

Next, navigate back to the other shell and start the MariaDB Docker container:

docker start mariadb

Examine MariaDB's logs to confirm the Galera cluster has synchronized:

# tail -1 /var/log/kolla/mariadb/mariadb.log
2021-12-08 22:27:39 2 [Note] WSREP: Synchronized with group, ready for
connections

References