Charmed PostgreSQL VM
- By Canonical Data Platform
- Databases
Channel | Revision | Published | Runs on |
---|---|---|---|
latest/stable | 345 | 09 Nov 2023 | |
latest/stable | 239 | 09 Feb 2022 | |
latest/stable | 226 | 01 Apr 2021 | |
14/stable | 468 | 11 Sep 2024 | |
14/stable | 467 | 11 Sep 2024 | |
14/candidate | 468 | 02 Sep 2024 | |
14/candidate | 467 | 02 Sep 2024 | |
14/beta | 468 | 02 Sep 2024 | |
14/beta | 467 | 02 Sep 2024 | |
14/edge | 482 | 27 Sep 2024 | |
14/edge | 481 | 27 Sep 2024 |
juju deploy postgresql --channel 14/stable
Deploy universal operators easily with Juju, the Universal Operator Lifecycle Manager.
Platform:
Charm Users explanations
There are two types of users in PostgreSQL:
- Internal users (used by charm operator)
- Relation/integration users (used by related applications)
- Extra user roles (if default permissions are not enough)
Internal users explanations:
The operator uses the following internal DB users:
-
postgres
- the initial/default PostgreSQL user. Used for very initial bootstrap only. -
operator
- the user that charm.py uses to manage database/cluster. -
replication
- the user performs replication between database PostgreSQL cluster members. -
rewind
- the internal user for synchronizing a PostgreSQL cluster with another copy of the same cluster. -
monitoring
- the user for COS integration. -
backups
- the user to perform/list/restore backups.
The full list of internal users is available in charm source code. The full dump of internal users (on the newly installed charm):
postgres=# \du
List of roles
Role name | Attributes | Member of
-------------+------------------------------------------------------------+--------------
backup | Superuser | {}
monitoring | | {pg_monitor}
operator | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
postgres | Superuser | {}
replication | Replication | {}
rewind | | {}
Note: it is forbidden to use/manage described above users! They are dedicated to the operators logic! Please use data-integrator charm to generate/manage/remove an external credentials.
It is allowed to rotate passwords for internal users using action ‘set-password’:
> juju show-action postgresql set-password
Change the system user's password, which is used by charm. It is for internal charm users and SHOULD NOT be used by applications.
Arguments
password:
type: string
description: The password will be auto-generated if this option is not specified.
username:
type: string
description: The username, the default value 'operator'. Possible values - operator, replication, rewind.
For example, to generate a new random password for internal user:
> juju run-action --wait postgresql/leader set-password username=operator
unit-postgresql-1:
UnitId: postgresql/1
id: "2"
results:
password: k4qqnWSZJZrcMt4B
status: completed
To set a predefined password for the specific user, run:
> juju run-action --wait postgresql/leader set-password username=operator password=newpassword
unit-postgresql-1:
UnitId: postgresql/1
id: "4"
results:
password: newpassword
status: completed
Note: the action set-password
must be executed on juju leader unit (to update peer relation data with new value).
Relation/integration users explanations:
The operator created a dedicated user for every application related/integrated with database. Those users are removed on the juju relation/integration removal request. However, DB data stays in place and can be reused on re-created relations (using new user credentials):
postgres=# \du
List of roles
Role name | Attributes | Member of
-------------+------------------------------------------------------------+--------------
..
relation-6 | | {}
relation-8 | | {}
...
Note: If password rotation is needed for users used in relations, it is needed to remove the relation and create it again:
> juju remove-relation postgresql myclientapp
> juju wait-for application postgresql
> juju relate postgresql myclientapp
Extra user roles
When an application charm requests a new user through the relation/integration it can specify that the user should have the admin
role in the extra-user-roles
field. The admin
role enables the new user to read and write to all databases (for the postgres
system database it can only read data) and also to create and delete non-system databases.
Note: extra-user-roles
is supported by modern interface postgresql_client
only and missing for legacy pgsql
interface. Read more about the supported charm interfaces here.