Providing Backups

The Operator usually stores Percona XtraDB Cluster backups on Amazon S3 or S3-compatible storage outside the Kubernetes cluster. But storing backups on Persistent Volumes inside the Kubernetes cluster is also possible.

The Operator allows doing backup in two ways. Scheduled backups are configured in the deploy/cr.yaml file to be executed automatically in proper time. On-demand backups can be done manually at any moment.

Making scheduled backups

Since backups are stored separately on the Amazon S3, a secret with AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY should be present on the Kubernetes cluster. The secrets file with these base64-encoded keys should be created: for example deploy/backup-s3.yaml file with the following contents:

apiVersion: v1
kind: Secret
metadata:
  name: my-cluster-name-backup-s3
type: Opaque
data:
  AWS_ACCESS_KEY_ID: UkVQTEFDRS1XSVRILUFXUy1BQ0NFU1MtS0VZ
  AWS_SECRET_ACCESS_KEY: UkVQTEFDRS1XSVRILUFXUy1TRUNSRVQtS0VZ

Note

The following command can be used to get a base64-encoded string from a plain text one: $ echo -n 'plain-text-string' | base64

The name value is the Kubernetes secret name which will be used further, and AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are the keys to access S3 storage (and obviously they should contain proper values to make this access possible). To have effect secrets file should be applied with the appropriate command to create the secret object, e.g. kubectl apply -f deploy/backup-s3.yaml (for Kubernetes).

Backups schedule is defined in the backup section of the deploy/cr.yaml file. This section contains following subsections:

  • storages subsection contains data needed to access the S3-compatible cloud to store backups.
  • schedule subsection allows to actually schedule backups (the schedule is specified in crontab format).

Here is an example of deploy/cr.yaml which uses Amazon S3 storage for backups:

...
backup:
  ...
  storages:
    s3-us-west:
      type: s3
      s3:
        bucket: S3-BACKUP-BUCKET-NAME-HERE
        region: us-west-2
        credentialsSecret: my-cluster-name-backup-s3
  ...
  schedule:
   - name: "sat-night-backup"
     schedule: "0 0 * * 6"
     keep: 3
     storageName: s3-us-west
  ...

if you use some S3-compatible storage instead of the original Amazon S3, the endpointURL is needed in the s3 subsection which points to the actual cloud used for backups and is specific to the cloud provider. For example, using Google Cloud involves the following endpointUrl:

endpointUrl: https://storage.googleapis.com

The options within these three subsections are further explained in the Custom Resource options.

One option which should be mentioned separately is credentialsSecret which is a Kubernetes secret for backups. Value of this key should be the same as the name used to create the secret object (my-cluster-name-backup-s3 in the last example).

The schedule is specified in crontab format as explained in Custom Resource options.

Making on-demand backup

To make an on-demand backup, the user should first configure the backup storage in the backup.storages subsection of the deploy/cr.yaml configuration file in a same way it was done for scheduled backups. When the deploy/cr.yaml file contains correctly configured storage and is applied with kubectl command, use a special backup configuration YAML file with the following contents:

  • backup name in the metadata.name key,
  • PXC Cluster name in the spec.pxcCluster key,
  • storage name from deploy/cr.yaml in the spec.storageName key.

The example of the backup configuration file is deploy/backup/backup.yaml.

When the backup destination is configured and applied with kubectl apply -f deploy/cr.yaml command, the actual backup command is executed:

kubectl apply -f deploy/backup/backup.yaml

Note

Storing backup settings in a separate file can be replaced by passing its content to the kubectl apply command as follows:

cat <<EOF | kubectl apply -f-
apiVersion: pxc.percona.com/v1
kind: PerconaXtraDBClusterBackup
metadata:
  name: backup1
spec:
  pxcCluster: cluster1
  storageName: s3-us-west
EOF

Storing backup on a private volume

Here is an example of the deploy/cr.yaml backup section fragment, which configures a private volume for filesystem-type storage:

...
backup:
  ...
  storages:
    fs-pvc:
      type: filesystem
      volume:
        persistentVolumeClaim:
          accessModes: [ "ReadWriteOnce" ]
          resources:
            requests:
              storage: 6Gi
  ...

Note

Please take into account that 6Gi storage size specified in this example may be insufficient for the real-life setups; consider using tens or hundreds of gigabytes. Also, you can edit this option later, and changes will take effect after applying the updated deploy/cr.yaml file with kubectl.

Enabling compression for backups

There is a possibility to enable LZ4 compression for backups.

Note

This feature is available only with PXC 8.0 and not PXC 5.7.

To enable compression, use pxc-configuration key in the deploy/cr.yaml configuration file to supply Percona XtraDB Cluster nodes with two additional my.cnf options under its [sst] and [xtrabackup] sections as follows:

pxc:
  image: percona/percona-xtradb-cluster:8.0.19-10.1
  configuration: |
    ...
    [sst]
    xbstream-opts=--decompress
    [xtrabackup]
    compress=lz4
    ...

When enabled, compression will be used for both backups and SST.

Restore the cluster from a previously saved backup

Backup can be restored not only on the Kubernetes cluster where it was made, but also on any Kubernetes-based environment with the installed Operator.

Note

When restoring to a new Kubernetes-based environment, make sure it has a Secrets object with the same user passwords as in the original cluster. More details about secrets can be found in System Users.

Following steps are needed to restore a previously saved backup:

  1. First of all make sure that the cluster is running.

  2. Now find out correct names for the backup and the cluster. Available backups can be listed with the following command:

    kubectl get pxc-backup
    

    Note

    Obviously, you can make this check only on the same cluster on which you have previously made the backup.

    And the following command will list existing Percona XtraDB Cluster names in the current Kubernetes-based environment:

    kubectl get pxc
    
  3. When both correct names are known, it is needed to set appropriate keys in the deploy/backup/restore.yaml file.

    • set spec.pxcCluster key to the name of the target cluster to restore the backup on,

    • if you are restoring backup on the same Kubernetes-based cluster you have

      used to save this backup, set spec.backupName key to the name of your backup,

    • if you are restoring backup on the Kubernetes-based cluster different from one you have used to save this backup, set spec.backupSource subsection instead of spec.backupName field to point on the appropriate PVC or S3-compatible storage:

      1. If backup was stored on the PVC volume, backupSource should contain the storage name (which should be configured in the main CR) and PVC Name:

        ...
        backupSource:
          destination: pvc/PVC_VOLUME_NAME
          storageName: pvc
          ...
        
      2. If backup was stored on the S3-compatible storage, backupSource should contain destination key equal to the s3 bucket with a special s3:// prefix, followed by the necessary S3 configuration keys, same as in deploy/cr.yaml file:

        ...
        backupSource:
          destination: s3://S3-BUCKET-NAME/BACKUP-NAME
          s3:
            credentialsSecret: my-cluster-name-backup-s3
            region: us-west-2
            endpointURL: https://URL-OF-THE-S3-COMPATIBLE-STORAGE
        ...
        

    After that, the actual restoration process can be started as follows:

    kubectl apply -f deploy/backup/restore.yaml
    

Note

Storing backup settings in a separate file can be replaced by passing its content to the kubectl apply command as follows:

cat <<EOF | kubectl apply -f-
apiVersion: "pxc.percona.com/v1"
kind: "PerconaXtraDBClusterRestore"
metadata:
  name: "restore1"
spec:
  pxcCluster: "cluster1"
  backupName: "backup1"
EOF

Delete the unneeded backup

Deleting a previously saved backup requires not more than the backup name. This name can be taken from the list of available backups returned by the following command:

kubectl get pxc-backup

When the name is known, backup can be deleted as follows:

kubectl delete pxc-backup/<backup-name>

Copy backup to a local machine

Make a local copy of a previously saved backup requires not more than the backup name. This name can be taken from the list of available backups returned by the following command:

kubectl get pxc-backup

When the name is known, backup can be downloaded to the local machine as follows:

./deploy/backup/copy-backup.sh <backup-name> path/to/dir

For example, this downloaded backup can be restored to the local installation of Percona Server:

service mysqld stop
rm -rf /var/lib/mysql/*
cat xtrabackup.stream | xbstream -x -C /var/lib/mysql
xtrabackup --prepare --target-dir=/var/lib/mysql
chown -R mysql:mysql /var/lib/mysql
service mysqld start

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