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Backup/Restore overview

k0s has integrated support for backing up cluster state and configuration. The k0s backup utility is aiming to back up and restore k0s managed parts of the cluster.

The backups created by k0s backup command have following pieces of your cluster:

  • certificates (the content of the <data-dir>/pki directory)
  • etcd snapshot, if the etcd datastore is used
  • Kine/SQLite snapshot, if the Kine/SQLite datastore is used
  • k0s.yaml
  • any custom defined manifests under the <data-dir>/manifests
  • any image bundles located under the <data-dir>/images
  • any helm configuration

Parts NOT covered by the backup utility:

  • PersistentVolumes of any running application
  • datastore, in case something else than etcd or Kine/SQLite is used
  • any configuration to the cluster introduced by manual changes (e.g. changes that weren't saved under the <data-dir>/manifests)

Any of the backup/restore related operations MUST be performed on the controller node.

Backup/restore a k0s node locally

Backup (local)

To create backup run the following command on the controller node:

k0s backup --save-path=<directory>

The directory used for the save-path value must exist and be writable. The default value is the current working directory. The command provides backup archive using following naming convention: k0s_backup_<ISODatetimeString>.tar.gz

Because of the DateTime usage, it is guaranteed that none of the previously created archives would be overwritten.

To output the backup archive to stdout, use - as the save path.

Restore (local)

To restore cluster state from the archive use the following command on the controller node:

k0s restore /tmp/k0s_backup_2021-04-26T19_51_57_000Z.tar.gz

The command would fail if the data directory for the current controller has overlapping data with the backup archive content.

The command would use the archived k0s.yaml as the cluster configuration description.

In case if your cluster is HA, after restoring single controller node, join the rest of the controller nodes to the cluster. E.g. steps for N nodes cluster would be:

  • Restore backup on fresh machine
  • Run controller there
  • Join N-1 new machines to the cluster the same way as for the first setup.

To read the backup archive from stdin, use - as the file path.

Encrypting backups (local)

By using - as the save or restore path, it is possible to pipe the backup archive through an encryption utility such as GnuPG or OpenSSL.

Note that unencrypted data will still briefly exist as temporary files on the local file system during the backup archvive generation.

Encrypting backups using GnuPG

Follow the instructions for your operating system to install the gpg command if it is not already installed.

This tutorial only covers the bare minimum for example purposes. For secure key management practices and advanced usage refer to the GnuPG user manual.

To generate a new key-pair, use:

gpg --gen-key

The key will be stored in your key ring.

gpg --list-keys

This will output a list of keys:

/home/user/.gnupg/pubring.gpg
------------------------------
pub   4096R/BD33228F 2022-01-13
uid                  Example User <user@example.com>
sub   4096R/2F78C251 2022-01-13

To export the private key for decrypting the backup on another host, note the key ID ("BD33228F" in this example) in the list and use:

gpg --export-secret-keys --armor BD33228F > k0s.key

To create an encrypted k0s backup:

k0s backup --save-path - | gpg --encrypt --recipient user@example.com > backup.tar.gz.gpg

Restoring encrypted backups using GnuPG

You must have the private key in your gpg keychain. To import the key that was exported in the previous example, use:

gpg --import k0s.key

To restore the encrypted backup, use:

gpg --decrypt backup.tar.gz.gpg | k0s restore -

Backup/restore a k0s cluster using k0sctl

With k0sctl you can perform cluster level backup and restore remotely with one command.

Backup (remote)

To create backup run the following command:

k0sctl backup

k0sctl connects to the cluster nodes to create a backup. The backup file is stored in the current working directory.

Restore (remote)

To restore cluster state from the archive use the following command:

k0sctl apply --restore-from /path/to/backup_file.tar.gz

The control plane load balancer address (externalAddress) needs to remain the same between backup and restore. This is caused by the fact that all worker node components connect to this address and cannot currently be re-configured.