[DPE-9555] fix(test): add explicit relation endpoints for GLAuth-PostgreSQL integration

[marceloneppel]

Issue

The test_glauth_integration integration test fails across PRs with:

juju.errors.JujuAPIError: ambiguous relation: "glauth-k8s glauth-postgresql-k8s" could refer to
  "glauth-k8s:pg-database glauth-postgresql-k8s:database";
  "glauth-postgresql-k8s:ldap glauth-k8s:ldap";
  "glauth-postgresql-k8s:receive-ca-cert glauth-k8s:send-ca-cert"

The test deploys glauth-postgresql-k8s (the backing PostgreSQL for GLAuth) from the 14/stable channel. On March 2, 2026, postgresql-k8s rev 774 was published to 14/stable, which added ldap (requires, interface ldap) and receive-ca-cert (requires, interface certificate_transfer) endpoints. These new endpoints match glauth-k8s's existing ldap (provides) and send-ca-cert (provides) endpoints, creating 3 possible interface pairs between the two charms instead of the previous single one (pg-database ↔ database). This makes the unqualified add_relation("glauth-k8s", "glauth-postgresql-k8s") call ambiguous.

The previous 14/stable revision (rev 494, from February 2025) did not have ldap or receive-ca-cert endpoints, so the relation was unambiguous.

Solution

Specify explicit endpoint names (glauth-k8s:pg-database and glauth-postgresql-k8s:database) when adding the database relation between GLAuth and its backing PostgreSQL instance.

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.96%. Comparing base (180b37a) to head (6dc805a).
⚠️ Report is 1 commits behind head on 16/edge.

❌ Your project status has failed because the head coverage (68.96%) is below the target coverage (70.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff            @@
##           16/edge    #1322   +/-   ##
========================================
  Coverage    68.96%   68.96%           
========================================
  Files           16       16           
  Lines         3809     3809           
  Branches       574      574           
========================================
  Hits          2627     2627           
  Misses         980      980           
  Partials       202      202           

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