Appendix B - Backup on object stores ==================================== .. raw:: html .. Warning:: As of CloudNativePG 1.26, **native Barman Cloud support is deprecated** in favor of the **Barman Cloud Plugin**. This page has been moved to the appendix for reference purposes. While the native integration remains functional for now, we strongly recommend beginning a gradual migration to the plugin-based interface after appropriate testing. For guidance, see `Migrating from Built-in CloudNativePG Backup `_ . 　 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. .. Note:: 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). 　 .. Warning:: Starting with Barman Cloud 3.16, most Barman Cloud commands no longer automatically create the target bucket, assuming it already exists. Only the `barman-cloud-check-wal-archive` command creates the bucket now. Whenever this is not the first operation run on an empty bucket, CloudNativePG will throw an error. As a result, to ensure reliable, future-proof operations and avoid potential issues, we strongly recommend that you create and configure your object store bucket *before* creating a `Cluster` resource that references it. 　 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 a compatible provider, please refer to :ref:`Appendix C - Common object stores for backups ` . WAL archiving ------------- WAL archiving is the process that feeds a :ref:`WAL archive ` in CloudNativePG. The WAL archive is defined in the ``.spec.backup.barmanObjectStore`` stanza of a ``Cluster`` resource. .. Note:: Please refer to `BarmanObjectStoreConfiguration `_ in the barman-cloud API for a full list of options. 　 If required, you can choose to compress WAL files as soon as they are uploaded and/or encrypt them: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: [...] wal: compression: gzip encryption: AES256 You can configure the encryption directly in your bucket, and the operator will use it unless you override it in the cluster configuration. PostgreSQL implements a sequential archiving scheme, where the ``archive_command`` will be executed sequentially for every WAL segment to be archived. .. Note:: By default, CloudNativePG sets `archive_timeout` to `5min` , ensuring that WAL files, even in case of low workloads, are closed and archived at least every 5 minutes, providing a deterministic time-based value for your Recovery Point Objective ( :ref:`PgBouncerPoolMode ` ). Even though you change the value of the `archive_timeout `_ , our experience suggests that the default value set by the operator is suitable for most use cases. 　 When the bandwidth between the PostgreSQL instance and the object store allows archiving more than one WAL file in parallel, you can use the parallel WAL archiving feature of the instance manager like in the following example: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: [...] wal: compression: gzip maxParallel: 8 encryption: AES256 In the previous example, the instance manager optimizes the WAL archiving process by archiving in parallel at most eight ready WALs, including the one requested by PostgreSQL. When PostgreSQL will request the archiving of a WAL that has already been archived by the instance manager as an optimization, that archival request will be just dismissed with a positive status. Retention policies ------------------ 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:: 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 - lz4 - snappy - xz - zstd The compression settings for backups and WALs are independent. See the `DataBackupConfiguration `_ and `WALBackupConfiguration `_ sections in the barman-cloud 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 and WAL commands --------------------------------------------- You can append additional options to the ``barman-cloud-backup`` and ``barman-cloud-wal-archive`` commands by using the ``additionalCommandArgs`` property in the ``.spec.backup.barmanObjectStore.data`` and ``.spec.backup.barmanObjectStore.wal`` sections respectively. These properties are lists of strings that will be appended to the ``barman-cloud-backup`` and ``barman-cloud-wal-archive`` commands. For example, you can use the ``--read-timeout=60`` to customize the connection reading timeout. For additional options supported by ``barman-cloud-backup`` and ``barman-cloud-wal-archive`` commands you can refer to the official barman documentation `here `_ . If an option provided in ``additionalCommandArgs`` is already present in the declared options in its section (``.spec.backup.barmanObjectStore.data`` or ``.spec.backup.barmanObjectStore.wal`` ), the extra option will be ignored. The following is an example of how to use this property: For backups: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: [...] data: additionalCommandArgs: - "--min-chunk-size=5MB" - "--read-timeout=60" For WAL files: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: backup: barmanObjectStore: [...] wal: additionalCommandArgs: - "--max-concurrency=1" - "--read-timeout=60" Recovery from an object store ----------------------------- You can recover from a backup created by Barman Cloud and stored on a supported object store. After you define the external cluster, including all the required configuration in the ``barmanObjectStore`` section, you need to reference it in the ``.spec.recovery.source`` option. This example defines a recovery object store in a blob container in Azure: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-restore spec: [...] superuserSecret: name: superuser-secret bootstrap: recovery: source: clusterBackup externalClusters: - name: clusterBackup barmanObjectStore: destinationPath: https://STORAGEACCOUNTNAME.blob.core.windows.net/CONTAINERNAME/ azureCredentials: storageAccount: name: recovery-object-store-secret key: storage_account_name storageKey: name: recovery-object-store-secret key: storage_account_key wal: maxParallel: 8 The previous example assumes that the application database and its owning user are named ``app`` by default. If the PostgreSQL cluster being restored uses different names, you must specify these names before exiting the recovery phase, as documented in :ref:`Configure the application database ` . .. Note:: By default, the `recovery` method strictly uses the `name` of the cluster in the `externalClusters` section as the name of the main folder of the backup data within the object store. This name is normally reserved for the name of the server. You can specify a different folder name using the `barmanObjectStore.serverName` property. 　 .. Note:: This example takes advantage of the parallel WAL restore feature, dedicating up to 8 jobs to concurrently fetch the required WAL files from the archive. This feature can appreciably reduce the recovery time. Make sure that you plan ahead for this scenario and correctly tune the value of this parameter for your environment. It will make a difference when you need it, and you will.