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MariaDB Operations

Tips and tricks for managing and operating the MariaDB cluster within a Genestack environment.

Connect to the database

Sometimes an operator may need to connect to the database to troubleshoot things or otherwise make modifications to the databases in place. The following command can be used to connect to the database from a node within the cluster.

mysql -h $(kubectl -n openstack get service mariadb-cluster-primary -o jsonpath='{.spec.clusterIP}') \
      -p$(kubectl --namespace openstack get secret mariadb -o jsonpath='{.data.root-password}' | base64 -d) \
      -u root

Info

The following command will leverage your kube configuration and dynamically source the needed information to connect to the MySQL cluster. You will need to ensure you have installed the mysql client tools on the system you're attempting to connect from.

Manually dumping and restoring databases

When running mysqldump or mariadbdump the following commands can be useful for generating a quick backup.

Individual Database Backups

mysqldump --host=$(kubectl -n openstack get service mariadb-cluster -o jsonpath='{.spec.clusterIP}')\
          --user=root \
          --password=$(kubectl --namespace openstack get secret mariadb -o jsonpath='{.data.root-password}' | base64 -d) \
          --single-transaction \
          --routines \
          --triggers \
          --events \
          ${DATABASE_NAME} \
          --result-file=/tmp/${DATABASE_NAME}-$(date +%s).sql

Dump all databases as individual files in /tmp

mysql -h $(kubectl -n openstack get service mariadb-cluster -o jsonpath='{.spec.clusterIP}') \
      -u root \
      -p$(kubectl --namespace openstack get secret mariadb -o jsonpath='{.data.root-password}' | base64 -d) \
      -e 'show databases;' \
      --column-names=false \
      --vertical | \
          awk '/[:alnum:]/' | \
              xargs -i mysqldump --host=$(kubectl -n openstack get service mariadb-cluster -o jsonpath='{.spec.clusterIP}') \
              --user=root \
              --password=$(kubectl --namespace openstack get secret mariadb -o jsonpath='{.data.root-password}' | base64 -d) \
              --single-transaction \
              --routines \
              --triggers \
              --events \
              {} \
              --result-file=/tmp/{}-$(date +%s).sql

Individual Database Restores

Ensure the destination database exists

The destination database must exist prior to restoring individual SQL backups. If it does not already exist, it's important to create the database with the correct charset and collate values. Failing to do so can result in errors such as Foreign Key Constraint is Incorrectly Formed during DB upgrades.

CREATE DATABASE ${DATABASE_NAME} DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_general_ci;

Restoring a database

mysql -h $(kubectl -n openstack get service mariadb-cluster-primary -o jsonpath='{.spec.clusterIP}') \
    -u root \
    -p$(kubectl --namespace openstack get secret mariadb -o jsonpath='{.data.root-password}' | base64 -d) \
    ${DATABASE_NAME} < /tmp/${DATABASE_FILE}

Restore using the MariaDB CRD

To restore the most recent successful backup, create the following resource to spawn a job that will mount the same storage as the backup and apply the dump to your MariaDB database.

Refer to the mariadb-operator restore documentation for more information.

Operator Restore Tips

  1. If you have multiple backups available, the operator is able to infer which backup to restore based on the spec.targetRecoveryTime field discussed in the operator documentation here.
  2. The referred database (db1 in the example below) must previously exist for the Restore to succeed.
  3. The mariadb CLI invoked by the operator under the hood only supports selecting a single database to restore via the --one-database option, restoration of multiple specific databases is not supported.

Restore All Databases

The following command may lead to data loss

cat <<EOF | kubectl -n openstack apply -f -
apiVersion: k8s.mariadb.com/v1alpha1
kind: Restore
metadata:
  name: maria-restore
spec:
  mariaDbRef:
    name: mariadb-cluster
  backupRef:
    name: mariadb-backup
EOF

Restore Single Database

The following command may lead to data loss

cat <<EOF | kubectl -n openstack apply -f -
apiVersion: k8s.mariadb.com/v1alpha1
kind: Restore
metadata:
  name: maria-restore
spec:
  mariaDbRef:
    name: mariadb-cluster
  backupRef:
    name: mariadb-backup
  databases: db1
EOF

Check Restore Progress

Simply get the restore object previously created

kubectl -n openstack get restore maria-restore

NAME            COMPLETE   STATUS    MARIADB           AGE
maria-restore   True       Success   mariadb-cluster   26s