Add Redis Observer

[amandahla]

Overview

This PR only adds integration with Redis. No changes are done while integrating it so far.

Rationale

The integration is required by Horizontal scaling configuration.

Juju Events Changes

redis_relation_updated added

Module Changes

Redis observer added

Library Changes

charms.redis_k8s.v0.redis added

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Manging Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated.
• The PR is tagged with appropriate label (urgent, trivial, complex)

Charmhub documentation will be updated when workload changes after integrating with Redis in further PR.

[cbartz]

Out of curiosity, why is there a PR just for this? As this is a small change, I would think it could be included in a future PR with a real use case. To have a basis for working on the horizontal scaling feature using multiple PR's in parallel?

[amandahla]

Out of curiosity, why is there a PR just for this? As this is a small change, I would think it could be included in a future PR with a real use case. To have a basis for working on the horizontal scaling feature using multiple PR's in parallel?

Yes, this is required by horizontal scaling configuration. I submitted this PR only with the integration so it's easier to review and see the impact in integration tests.

[github-actions]

Test coverage for d8995aa

Name                            Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------------------
src/actions/__init__.py             3      0      0      0   100%
src/actions/register_user.py       22      0      2      0   100%
src/actions/reset_instance.py      21      0      2      0   100%
src/admin_access_token.py          48     32     12      0    27%   52-92
src/backup.py                     197      5     30      2    97%   404-405, 474-475, 531->533, 534
src/backup_observer.py            133     16     14      0    89%   130-133, 138-141, 177-180, 209-212
src/charm.py                      182      4     36      1    98%   162-163, 226-227
src/charm_state.py                 63      1     10      1    97%   127
src/charm_types.py                 23      0      6      0   100%
src/database_client.py             53      1     10      3    94%   35, 47->exit, 69->exit
src/database_observer.py           48      4      4      0    92%   69-71, 87
src/exceptions.py                   4      1      0      0    75%   22
src/mjolnir.py                     84     12     24      2    83%   64-72, 81, 173-174
src/observability.py                9      0      0      0   100%
src/pebble.py                     102     12     16      6    85%   95-96, 98-99, 107, 109, 111, 115, 136-137, 152-153
src/redis_observer.py              18      1      0      0    94%   43
src/saml_observer.py               45      1      8      0    98%   64
src/smtp_observer.py               70      3     14      1    95%   70-74, 96->101
src/synapse/__init__.py             4      0      0      0   100%
src/synapse/admin.py               20      9      2      0    50%   40-41, 63-74
src/synapse/api.py                161      2     22      2    98%   207, 376
src/synapse/workload.py           279      8     44      6    96%   425->exit, 454-455, 507-508, 544-545, 561, 610->613, 659, 667->669, 669->671
src/user.py                        24      0      4      0   100%
---------------------------------------------------------------------------
TOTAL                            1613    112    260     24    92%

Static code analysis report

Run started:2024-02-21 13:42:43.010498

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 8455
  Total lines skipped (#nosec): 4
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):