[MISC] Sanitize PostgreSQL extra-user-roles arg

[sinclert-canonical]

This PR contains a slight refactor to sync code with PostgreSQL VM / K8s operator codebases.

Changes:

• Start leveraging PostgreSQL lib PERMISSIONS_GROUP_ADMIN constant.
• Start passing PostgreSQL lib create-user extra_user_roles argument as a list.

[codecov]

Codecov Report

Attention: Patch coverage is 53.84615% with 6 lines in your changes missing coverage. Please review.

Project coverage is 75.11%. Comparing base (000f9c8) to head (3f732ef).

Files with missing lines	Patch %	Lines
src/charm.py	25.00%	3 Missing ⚠️
src/relations/pgbouncer_provider.py	66.66%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #506      +/-   ##
==========================================
- Coverage   75.20%   75.11%   -0.10%     
==========================================
  Files           9        9              
  Lines        1319     1326       +7     
  Branches      239      241       +2     
==========================================
+ Hits          992      996       +4     
- Misses        254      256       +2     
- Partials       73       74       +1     

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[sinclert-canonical]

Not sure why the test-db tests and the test-backend-database tests fail consistently 🤔

[dragomirp]

Not sure why the test-db tests and the test-backend-database tests fail consistently 🤔

Pgbouncer is a subordinate charm and has to run on both Jammy (py 3.10) and Focal (py 3.8). The list typing doesn't seem to work on python 3.8:

unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install Traceback (most recent call last):
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install   File "/var/lib/juju/agents/unit-pgbouncer-1/charm/src/charm.py", line 25, in <module>
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install     from charms.postgresql_k8s.v0.postgresql import PERMISSIONS_GROUP_ADMIN
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install   File "/var/lib/juju/agents/unit-pgbouncer-1/charm/lib/charms/postgresql_k8s/v0/postgresql.py", line 104, in <module>
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install     class PostgreSQL:
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install   File "/var/lib/juju/agents/unit-pgbouncer-1/charm/lib/charms/postgresql_k8s/v0/postgresql.py", line 226, in PostgreSQL
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install     extra_user_roles: Optional[list[str]] = None,
unit-pgbouncer-1: 11:12:20 WARNING unit.pgbouncer/1.install TypeError: 'type' object is not subscriptable

We will have to change the lib to Optional[List[str]] for backwards compatibility.

[sinclert-canonical]

The list typing doesn't seem to work on python 3.8.

Right, that Python >= 3.10 syntax is coming from the recently merged PostgreSQL charm lib...

I would rather leave this PR frozen in time, until we decide to bump the minimum Python version in this repository, than to open another round of 3+ PRs just to revert a function signature. WDYT?

[dragomirp]

Right, that Python >= 3.10 syntax is coming from the recently merged PostgreSQL charm lib...

I would rather leave this PR frozen in time, until we decide to bump the minimum Python version in this repository, than to open another round of 3+ PRs just to revert a function signature. WDYT?

There's no plan for updating the python version ATM, since that is what's available in Focal. The charm lib has to work on 3.8.

[sinclert-canonical]

PR rebased assuming the PostgreSQL k8s operator PR fixing the function signature will be merged.