Database Role Management v1

From its inception, EDB Postgres for Kubernetes has managed the creation of specific roles required in PostgreSQL instances:

  • some reserved users, such as the postgres superuser, streaming_replica and cnp_pooler_pgbouncer (when the PgBouncer Pooler is used)
  • The application user, set as the low-privilege owner of the application database

This process is described in the "Bootstrap" section.

With the managed stanza in the cluster spec, EDB Postgres for Kubernetes now provides full lifecycle management for roles specified in .spec.managed.roles.

This feature enables declarative management of existing roles, as well as the creation of new roles if they are not already present in the database. Role creation will occur after the database bootstrapping is complete.

An example manifest for a cluster with declarative role management can be found in the file cluster-example-with-roles.yaml.

Here is an excerpt from that file:

kind: Cluster
    - name: dante
      ensure: present
      comment: Dante Alighieri
      login: true
      superuser: false
        - pg_monitor
        - pg_signal_backend

The role specification in spec.managed.roles adheres to the PostgreSQL structure and naming conventions. Please refer to the API reference for the full list of attributes you can define for each role.

A few points are worth noting:

  1. The ensure attribute is not part of PostgreSQL. It enables declarative role management to create and remove roles. The two possible values are present (the default) and absent.
  2. The inherit attribute is true by default, following PostgreSQL conventions.
  3. The connectionLimit attribute defaults to -1, in line with PostgreSQL conventions.
  4. Role membership with inRoles defaults to no memberships.

Declarative role management ensures that PostgreSQL instances align with the spec. If a user modifies role attributes directly in the database, the EDB Postgres for Kubernetes operator will revert those changes during the next reconciliation cycle.

Unrealizable role configurations

In PostgreSQL, in some cases, commands cannot be honored by the database and will be rejected. Please refer to the PostgreSQL documentation on error codes for details.

Role operations can produce such fundamental errors. Two examples:

  • We ask PostgreSQL to create the role petrarca as a member of the role (group) poets, but poets does not exist.
  • We ask PostgreSQL to drop the role dante, but the role dante is the owner of the database inferno.

These fundamental errors cannot be fixed by the database, nor the EDB Postgres for Kubernetes operator, without clarification from the human administrator. The two examples above could be fixed by creating the role poets or dropping the database inferno respectively, but they might have originated due to human error, and in such case, the "fix" proposed might be the wrong thing to do.

EDB Postgres for Kubernetes will record when such fundamental errors occur, and will display them in the cluster Status. Which segues into…

Status of managed roles

The CRD status includes a section for the managed roles' status, as shown below:

      - app
      - dante
      - petrarca
      - ariosto
      - postgres
      - streaming_replica
      - 'could not perform DELETE on role dante: owner of database inferno'
      - 'could not perform UPDATE_MEMBERSHIPS on role petrarca: role "poets" does not exist'

Note the special sub-section cannotReconcile for operations the database (and EDB Postgres for Kubernetes) cannot honor, and which require human intervention.

This section covers roles reserved for operator use and those that are not under declarative management, providing a comprehensive view of the roles in the database instances.


In terms of backward compatibility, declarative role management is designed to ignore roles that exist in the database but are not included in the spec. The lifecycle of these roles will continue to be managed within PostgreSQL, allowing EDB Postgres for Kubernetes users to adopt this feature at their convenience.