Recovery ======== .. raw:: html In PostgreSQL, **recovery** refers to the process of starting an instance from an existing physical backup. PostgreSQL’s recovery system is robust and feature-rich, supporting **Point-In-Time Recovery (PITR)**—the ability to restore a cluster to any specific moment, from the earliest available backup to the latest archived WAL file. .. Note:: A valid WAL archive is required to perform PITR. 　 In CloudNativePG, recovery is **not performed in-place** on an existing cluster. Instead, it is used to **bootstrap a new cluster** from a physical backup. .. Note:: For more details on configuring the `bootstrap` stanza, refer to :ref:`Bootstrap ` . 　 The ``recovery`` bootstrap mode allows you to initialize a cluster from a physical base backup and replay the associated WAL files to bring the system to a consistent and optionally point-in-time state. CloudNativePG supports recovery via: - A **pluggable backup and recovery interface (CNPG-I)**, enabling integration with external tools such as the `Barman Cloud Plugin `_ . - **Native recovery from volume snapshots**, where supported by the underlying Kubernetes storage infrastructure. - **Native recovery from object stores via Barman Cloud**, which is **deprecated** as of version 1.26 in favor of the plugin-based approach. With the deprecation of native Barman Cloud support in version 1.26, this section now focuses on two supported recovery methods: using the **Barman Cloud Plugin** for recovery from object stores, and the **native interface** for recovery from volume snapshots. .. Note:: For legacy documentation, see :ref:`Appendix B – Recovery from an Object Store ` . 　 Recovery from an Object Store with the Barman Cloud Plugin ---------------------------------------------------------- This section outlines how to recover a PostgreSQL cluster from an object store using the recommended Barman Cloud Plugin. .. Note:: The object store must contain backup data produced by a CloudNativePG `Cluster` —either using the **deprecated native Barman Cloud integration** or the **Barman Cloud Plugin**. 　 .. Note:: For full details, refer to the `“Recovery of a Postgres Cluster” section in the Barman Cloud Plugin documentation `_ . 　 Begin by defining the object store that holds both your base backups and WAL files. The Barman Cloud Plugin uses a custom ``ObjectStore`` resource for this purpose. The following example shows how to configure one for Azure Blob Storage: .. code:: yaml apiVersion: barmancloud.cnpg.io/v1 kind: ObjectStore metadata: name: cluster-example-backup spec: configuration: 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 Next, configure the ``Cluster`` resource to use the ``ObjectStore`` you defined. In the ``bootstrap`` section, specify the recovery source, and define an ``externalCluster`` entry that references the plugin: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-restore spec: [...] superuserSecret: name: superuser-secret bootstrap: recovery: source: origin externalClusters: - name: origin plugin: name: barman-cloud.cloudnative-pg.io parameters: barmanObjectName: cluster-example-backup serverName: cluster-example Recovery from ``VolumeSnapshot`` Objects ---------------------------------------- .. Warning:: When creating replicas after recovering a primary instance from a `VolumeSnapshot` , the operator may fall back to using `pg_basebackup` to synchronize them. This process can be significantly slower—especially for large databases—because it involves a full base backup. This limitation will be addressed in the future with support for online backups and PVC cloning in the scale-up process. 　 CloudNativePG allows you to create a new cluster from a ``VolumeSnapshot`` of a ``PersistentVolumeClaim`` (PVC) that belongs to an existing ``Cluster`` . These snapshots are created using the declarative API for :ref:`How to configure Volume Snapshot backups ` . To complete the recovery process, the new cluster must also reference an external cluster that provides access to the WAL archive needed to reapply changes and finalize the recovery. The following example shows a cluster being recovered using both a ``VolumeSnapshot`` for the base backup and a WAL archive accessed through the Barman Cloud Plugin: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-restore spec: [...] bootstrap: recovery: source: origin volumeSnapshots: storage: name: kind: VolumeSnapshot apiGroup: snapshot.storage.k8s.io externalClusters: - name: origin plugin: name: barman-cloud.cloudnative-pg.io parameters: barmanObjectName: cluster-example-backup serverName: cluster-example In case the backed-up cluster was using a separate PVC to store the WAL files, the recovery must include that too: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-restore spec: [...] bootstrap: recovery: volumeSnapshots: storage: name: kind: VolumeSnapshot apiGroup: snapshot.storage.k8s.io walStorage: name: kind: VolumeSnapshot apiGroup: snapshot.storage.k8s.io 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 ` . .. Warning:: If bootstrapping a replica-mode cluster from snapshots, to leverage snapshots for the standby instances and not just the primary, we recommend that you: 1. Start with a single instance replica cluster. The primary instance will be recovered using the snapshot, and available WALs from the source cluster. 2. Take a snapshot of the primary in the replica cluster. 3. Increase the number of instances in the replica cluster as desired. 　 Recovery from a ``Backup`` object --------------------------------- If a ``Backup`` resource is already available in the namespace in which you need to create the cluster, you can specify the name using ``.spec.bootstrap.recovery.backup.name`` , as in the following example: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-example-initdb spec: instances: 3 bootstrap: recovery: backup: name: backup-example storage: size: 1Gi This bootstrap method allows you to specify just a reference to the backup that needs to be restored. 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 ` . Additional Considerations ------------------------- Whether you recover from an object store, a volume snapshot, or an existing ``Backup`` resource, no changes to the database, including the catalog, are permitted until the ``Cluster`` is fully promoted to primary and accepts write operations. This restriction includes any role overrides, which are deferred until the ``Cluster`` transitions to primary. As a result, the following considerations apply: - The application database name and user are copied from the backup being restored. The operator does not currently back up the underlying secrets, as this is part of the usual maintenance activity of the Kubernetes cluster. - To preserve the original postgres user password, configure ``enableSuperuserAccess`` and supply a ``superuserSecret`` . By default, recovery continues up to the latest available WAL on the default target timeline (``latest`` ). You can optionally specify a ``recoveryTarget`` to perform a point-in-time recovery (see :ref:`Point in time recovery (PITR) ` ). .. Note:: Consider using the `barmanObjectStore.wal.maxParallel` option to speed up WAL fetching from the archive by concurrently downloading the transaction logs from the recovery object store. 　 Point in time recovery (PITR) ----------------------------- Instead of replaying all the WALs up to the latest one, after extracting a base backup, you can ask PostgreSQL to stop replaying WALs at any given point in time. PostgreSQL uses this technique to achieve PITR. The presence of a WAL archive is mandatory. .. Note:: PITR requires you to specify a recovery target by using the options described in :ref:`Recovery targets ` . 　 The operator generates the configuration parameters required for this feature to work if you specify a recovery target. PITR from an object store ^^^^^^^^^^^^^^^^^^^^^^^^^ This example uses the same recovery object store in Azure defined earlier for the Barman Cloud plugin, containing both the base backups and the WAL archive. The recovery target is based on a requested timestamp. .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-restore-pitr spec: instances: 3 storage: size: 5Gi bootstrap: recovery: # Recovery object store containing WAL archive and base backups source: origin recoveryTarget: # Time base target for the recovery targetTime: "2023-08-11 11:14:21.00000+02" externalClusters: - name: origin plugin: name: barman-cloud.cloudnative-pg.io parameters: barmanObjectName: cluster-example-backup serverName: cluster-example In this example, you had to specify only the ``targetTime`` in the form of a timestamp. You didn’t have to specify the base backup from which to start the recovery. The ``backupID`` option is the one that allows you to specify the base backup from which to initiate the recovery process. By default, this value is empty. If you assign a value to it (in the form of a Barman backup ID), the operator uses that backup as the base for the recovery. .. Note:: You need to make sure that such a backup exists and is accessible. 　 If you don’t specify the backup ID, the operator detects the base backup for the recovery as follows: - When you use ``targetTime`` or ``targetLSN`` , the operator selects the closest backup that was completed before that target. - Otherwise, the operator selects the last available backup, in chronological order. Point-in-Time Recovery (PITR) from ``VolumeSnapshot`` Objects ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The following example demonstrates how to perform a **Point-in-Time Recovery (PITR)** using: - A Kubernetes ``VolumeSnapshot`` of the ``PGDATA`` directory, which provides the base backup. This snapshot is specified in the ``recovery.volumeSnapshots`` section and is named ``test-snapshot-1`` . - A recovery object store (in this case, MinIO) containing the archived WAL files. The object store is defined via a Barman Cloud Plugin ``ObjectStore`` resource (not shown here), and referenced using the ``recovery.source`` field, which points to an external cluster configuration. The cluster will be restored to a specific point in time using the ``recoveryTarget.targetTime`` option. .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-example-snapshot spec: # ... bootstrap: recovery: source: origin volumeSnapshots: storage: name: test-snapshot-1 kind: VolumeSnapshot apiGroup: snapshot.storage.k8s.io recoveryTarget: targetTime: "2023-07-06T08:00:39" externalClusters: - name: origin plugin: name: barman-cloud.cloudnative-pg.io parameters: barmanObjectName: minio-backup serverName: cluster-example This setup enables CloudNativePG to restore the base data from a volume snapshot and apply WAL segments from the object store to reach the desired recovery target. .. Note:: If the backed-up cluster had `walStorage` enabled, you also must specify the volume snapshot containing the `PGWAL` directory, as mentioned in :ref:`Recovery from VolumeSnapshot objects ` . 　 .. Warning:: It's your responsibility to ensure that the end time of the base backup in the volume snapshot is before the recovery target timestamp. 　 .. Warning:: If you added or removed a :ref:`TablespaceConfiguration ` in your cluster since the last base backup, replaying the WAL will fail. You need a base backup between the time of the tablespace change and the recovery target timestamp. 　 Recovery targets ^^^^^^^^^^^^^^^^ Here are the recovery target criteria you can use: targetTime Time stamp up to which recovery proceeds, expressed in `RFC 3339 `_ format. (The precise stopping point is also influenced by the ``exclusive`` option.) .. Warning:: PostgreSQL recovery will stop when it encounters the first transaction that occurs after the specified time. If no such transaction exists after the target time, the recovery process will fail. 　 targetXID Transaction ID up to which recovery proceeds. (The precise stopping point is also influenced by the ``exclusive`` option.) Keep in mind that while transaction IDs are assigned sequentially at transaction start, transactions can complete in a different numeric order. The transactions that are recovered are those that committed before (and optionally including) the specified one. targetName Named restore point (created with ``pg_create_restore_point()`` ) to which recovery proceeds. targetLSN LSN of the write-ahead log location up to which recovery proceeds. (The precise stopping point is also influenced by the ``exclusive`` option.) targetImmediate Recovery ends as soon as a consistent state is reached, that is, as early as possible. When restoring from an online backup, this means the point where taking the backup ended. .. Note:: The operator can retrieve the closest backup when you specify either `targetTime` or `targetLSN` . However, this isn't possible for the remaining targets: `targetName` , `targetXID` , and `targetImmediate` . In such cases, it's mandatory to specify `backupID` . 　 This example uses a ``targetName`` -based recovery target: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] bootstrap: recovery: source: origin recoveryTarget: backupID: 20220616T142236 targetName: restore_point_1 [...] You can choose only a single one among the targets in each ``recoveryTarget`` configuration. Additionally, you can specify ``targetTLI`` to force recovery to a specific timeline. By default, the previous parameters are considered to be inclusive, stopping just after the recovery target, matching `the behavior in PostgreSQL `_ . You can request exclusive behavior, stopping right before the recovery target, by setting the ``exclusive`` parameter to ``true`` . The following example shows this behavior, relying on a blob container in Azure for both base backups and the WAL archive: .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster metadata: name: cluster-restore-pitr spec: instances: 3 storage: size: 5Gi bootstrap: recovery: source: origin recoveryTarget: backupID: 20220616T142236 targetName: "maintenance-activity" exclusive: true externalClusters: - name: origin plugin: name: barman-cloud.cloudnative-pg.io parameters: barmanObjectName: cluster-example-backup serverName: cluster-example Configure the application database ---------------------------------- For the recovered cluster, you can configure the application database name and credentials with additional configuration. To update application database credentials, you can generate your own passwords, store them as secrets, and update the database to use the secrets. Or you can also let the operator generate a secret with a randomly secure password for use. See :ref:`Bootstrap an empty cluster (`initdb` ) ` for more information about secrets. .. Note:: While the `Cluster` is in recovery mode, no changes to the database, including the catalog, are permitted. This restriction includes any role overrides, which are deferred until the `Cluster` transitions to primary. During this phase, users remain as defined in the source cluster. 　 The following example configures the ``app`` database with the owner ``app`` and the password stored in the provided secret ``app-secret`` , following the bootstrap from a live cluster. .. code:: yaml apiVersion: postgresql.cnpg.io/v1 kind: Cluster [...] spec: bootstrap: recovery: database: app owner: app secret: name: app-secret [...] With the above configuration, the following will happen only **after recovery is completed**: 1. If the ``app`` database does not exist, it will be created. 2. If the ``app`` user does not exist, it will be created. 3. If the ``app`` user is not the owner of the ``app`` database, ownership will be granted to the ``app`` user. 4. If the ``owner`` value matches the ``username`` value in the secret, the password for the application user (the ``app`` user in this case) will be updated to the ``password`` value in the secret. How recovery works under the hood --------------------------------- .. raw:: html .. raw:: html You can use the data uploaded to the object storage to *bootstrap* a new cluster from an existing backup. The operator orchestrates the recovery process using the ``barman-cloud-restore`` tool (for the base backup) and the ``barman-cloud-wal-restore`` tool (for WAL files, including parallel support, if requested). For details and instructions on the ``recovery`` bootstrap method, see :ref:`Bootstrap from a backup (`recovery` ) ` . .. Note:: If you're not familiar with how `PostgreSQL PITR `_ works, we suggest that you configure the recovery cluster as the original one when it comes to ``.spec.postgresql.parameters`` . Once the new cluster is restored, you can then change the settings as desired. 　 The way it works is that the operator injects an init container in the first instance of the new cluster, and the init container starts recovering the backup from the object storage. .. Note:: The duration of the base backup copy in the new PVC depends on the size of the backup, as well as the speed of both the network and the storage. 　 When the base backup recovery process is complete, the operator starts the Postgres instance in recovery mode. In this phase, PostgreSQL is up, though not able to accept connections, and the pod is healthy according to the liveness probe. By way of the ``restore_command`` , PostgreSQL starts fetching WAL files from the archive. You can speed up this phase by setting the ``maxParallel`` option and enabling the parallel WAL restore capability. This phase terminates when PostgreSQL reaches the target, either the end of the WAL or the required target in case of PITR. You can optionally specify a ``recoveryTarget`` to perform a PITR. If left unspecified, the recovery continues up to the latest available WAL on the default target timeline (``latest`` ). Once the recovery is complete, the operator sets the required superuser password into the instance. The new primary instance starts as usual, and the remaining instances join the cluster as replicas. The process is transparent for the user and is managed by the instance manager running in the pods. Restoring into a Cluster with a Backup Section ---------------------------------------------- When restoring a cluster, the manifest may include a ``plugins`` section with Barman Cloud plugin pointing to a *backup* object store resource. This enables the newly created cluster to begin archiving WAL files and taking backups immediately after recovery—provided backup policies are configured. Avoid reusing the same ``ObjectStore`` configuration for both *backup* and *recovery* in the same cluster. If you must, ensure that each cluster uses a unique ``serverName`` to prevent accidental overwrites of backup or WAL archive data. .. Warning:: CloudNativePG includes a safety check to prevent a cluster from overwriting existing data in a shared storage bucket. If a conflict is detected, the cluster remains in the `Setting up primary` state, and the associated pods will fail with an error. The pod logs will display: `ERROR: WAL archive check failed for server recoveredCluster: Expected empty archive` . 　 .. Note:: You can bypass this safety check by setting the `cnpg.io/skipEmptyWalArchiveCheck` annotation to `enabled` on the recovered cluster. However, this is strongly discouraged unless you are highly familiar with PostgreSQL's recovery process. Skipping the check incorrectly can lead to severe data loss. Use with caution and only in expert scenarios.