Backup on object stores ======================= CloudNativePG natively supports **online/hot backup** of PostgreSQL clusters through continuous physical backup and WAL archiving on an object store. This means that the database is always up (no downtime required) and that Point In Time Recovery is available. The operator can orchestrate a continuous backup infrastructure that is based on the `Barman Cloud `_ tool. Instead of using the classical architecture with a Barman server, which backs up many PostgreSQL instances, the operator relies on the ``barman-cloud-wal-archive`` , ``barman-cloud-check-wal-archive`` , ``barman-cloud-backup`` , ``barman-cloud-backup-list`` , and ``barman-cloud-backup-delete`` tools. As a result, base backups will be *tarballs*. Both base backups and WAL files can be compressed and encrypted. For this, it is required to use an image with ``barman-cli-cloud`` included. You can use the image ``ghcr.io/cloudnative-pg/postgresql`` for this scope, as it is composed of a community PostgreSQL image and the latest ``barman-cli-cloud`` package. .. Important:: Always ensure that you are running the latest version of the operands in your system to take advantage of the improvements introduced in Barman cloud (as well as improve the security aspects of your cluster). A backup is performed from a primary or a designated primary instance in a ``Cluster`` (please refer to :ref:`Replica clusters ` for more information about designated primary instances), or alternatively on a :ref:`Backup from a standby ` . Common object stores -------------------- If you are looking for a specific object store such as :ref:`AWS S3 ` , :ref:`Microsoft Azure Blob Storage ` , :ref:`Google Cloud Storage ` , or :ref:`MinIO Gateway ` , or a compatible provider, please refer to :ref:`Appendix A - Common object stores for backups ` . Retention policies ------------------ .. Important:: Retention policies are not currently available on volume snapshots. CloudNativePG can manage the automated deletion of backup files from the backup object store, using **retention policies** based on the recovery window. Internally, the retention policy feature uses ``barman-cloud-backup-delete`` with ``--retention-policy “RECOVERY WINDOW OF {{ retention policy value }} {{ retention policy unit }}”`` . For example, you can define your backups with a retention policy of 30 days as follows: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: destinationPath: "" s3Credentials: accessKeyId: name: aws-creds key: ACCESS_KEY_ID secretAccessKey: name: aws-creds key: ACCESS_SECRET_KEY retentionPolicy: "30d" .. Note "There's more ...":: The **recovery window retention policy** is focused on the concept of *Point of Recoverability* (`PoR` ), a moving point in time determined by `current time - recovery window` . The *first valid backup* is the first available backup before `PoR` (in reverse chronological order). CloudNativePG must ensure that we can recover the cluster at any point in time between `PoR` and the latest successfully archived WAL file, starting from the first valid backup. Base backups that are older than the first valid backup will be marked as *obsolete* and permanently removed after the next backup is completed. Compression algorithms ---------------------- CloudNativePG by default archives backups and WAL files in an uncompressed fashion. However, it also supports the following compression algorithms via ``barman-cloud-backup`` (for backups) and ``barman-cloud-wal-archive`` (for WAL files): - bzip2 - gzip - snappy The compression settings for backups and WALs are independent. See the :ref:`DataBackupConfiguration {postgresql-cnpg-io-v1-DataBackupConfiguration} ` and :ref:`WalBackupConfiguration {postgresql-cnpg-io-v1-WalBackupConfiguration} ` sections in the API reference. It is important to note that archival time, restore time, and size change between the algorithms, so the compression algorithm should be chosen according to your use case. The Barman team has performed an evaluation of the performance of the supported algorithms for Barman Cloud. The following table summarizes a scenario where a backup is taken on a local MinIO deployment. The Barman GitHub project includes a `deeper analysis `_ . .. csv-table:: :header: Compression,Backup Time (ms),Restore Time (ms),Uncompressed size (MB),Compressed size (MB),Approx ratio :widths: 10,10,10,8,8,8 :align: left :class: longtable None,10927,7553,395,395,1:1 bzip2,25404,13886,395,67,5.9:1 gzip,116281,3077,395,91,4.3:1 snappy,8134,8341,395,166,2.4:1 Tagging of backup objects ------------------------- Barman 2.18 introduces support for tagging backup resources when saving them in object stores via ``barman-cloud-backup`` and ``barman-cloud-wal-archive`` . As a result, if your PostgreSQL container image includes Barman with version 2.18 or higher, CloudNativePG enables you to specify tags as key-value pairs for backup objects, namely base backups, WAL files and history files. You can use two properties in the ``.spec.backup.barmanObjectStore`` definition: - ``tags`` : key-value pair tags to be added to backup objects and archived WAL file in the backup object store - ``historyTags`` : key-value pair tags to be added to archived history files in the backup object store The excerpt of a YAML manifest below provides an example of usage of this feature: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: [...] tags: backupRetentionPolicy: "expire" historyTags: backupRetentionPolicy: "keep" Extra options for the backup command ------------------------------------ You can append additional options to the ``barman-cloud-backup`` command by using the ``additionalCommandArgs`` property in the ``.spec.backup.barmanObjectStore.data`` section. This property is a list of strings that will be appended to the ``barman-cloud-backup`` command. For example, you can use the ``--read-timeout=60`` to customize the connection reading timeout. For additional options supported by ``barman-cloud-backup`` you can refer to the official barman documentation `here `_ . If an option provided in ``additionalCommandArgs`` is already present in the declared options in the ``barmanObjectStore`` section, the extra option will be ignored. The following is an example of how to use this property: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: [...] data: additionalCommandArgs: - "--min-chunk-size=5MB" - "--read-timeout=60"