CloudNativePG Bootstrap Methods

• The bootstrap section within a cluster specification defines the method CloudNativePG uses to initialize a PostgreSQL cluster.

Bootstrap Methods

• initdb: (Default) Initializes a new PostgreSQL cluster.
• recovery: Creates a PostgreSQL cluster by restoring from a base backup and replaying available WAL files, potentially up to a specific point in time.
• pg_basebackup: Creates a PostgreSQL cluster by cloning an existing one of the same major version using pg_basebackup via streaming replication.
• recovery and pg_basebackup create a new cluster based on another one, differing from initdb.
• recovery and pg_basebackup can be used to create replica clusters and rely on external cluster definitions.

External Clusters

• The externalClusters section specifies PostgreSQL clusters associated with the current configuration.
• Use cases include:
  • Importing databases via logical backup and restore (initdb bootstrap method).
  • Cross-region replication using physical replication across Kubernetes clusters or traditional environments.
  • Recovering a PostgreSQL cluster from a physical base backup (fully or to a point-in-time).
• This section will be extended with logical replication and foreign servers in future releases.
• externalClusters defines the source PostgreSQL cluster for the pg_basebackup or recovery methods.
• An external cluster definition requires:
  • A name to identify the origin cluster, referenced by the source option.
  • Streaming connection information and/or recovery object store information.
• A recovery object store is a Barman Cloud compatible object store (e.g., AWS S3, Azure Blob Storage, Google Cloud Storage) managed by Barman Cloud, which contains:
  • WAL archive, which is required for Point In Time Recovery.
  • Catalog of physical base backups.
• Only defining a streaming connection allows the source to be used for the pg_basebackup method.
• Only defining a recovery object store allows the source to be used for the recovery method.
• Defining both allows either bootstrap method to be chosen.

Replica Cluster Mode

• In cases of pg_basebackup or full recovery point in time, the cluster is eligible for replica cluster mode.
• Replica clusters are continuously updated from the source via streaming, WAL shipping through PostgreSQL's restore_command, or both.

Password Files

• When a password is provided in an externalClusters entry, CloudNativePG manages a PostgreSQL password file for it.
• The password file is located at /controller/external/NAME/pgpass in each instance.
• CloudNativePG securely connects to the external server without exposing passwords in the connection string, using the passfile connection parameter.

Bootstrap initdb

• The command initdb creates a new PostgreSQL cluster from scratch and is the default bootstrap method.
• The command initdb creates a new PGDATA folder.
• superuserSecret will use the postgres superuser from the secret.
• It can create a new database using the initdb configuration.
• It can create an unprivileged user for the application database.
• Passwords can be generated and stored as secrets, or automatically generated by the operator.
• Secrets for usernames and passwords should comply with the kubernetes.io/basic-auth type.
• The application database is used to store application data, and applications should connect using the application database's owner.