Rabbitmq integration plus integrations refactor

[javierdelapuente]

Applicable spec: ISD175 - RabbitMQ support in paas-charm

Overview

Support RabbitMQ in paas-app-charmer.

There are two different charms that provider RabbitMQ, rabbitmq-server and rabbitmq-k8s. A new library has done, based on the one in rabbitmq-k8s, paas_app_charmer.rabbitmq.RabbitMQRequires that provides a common interface to both charms, and provides a RabbitMQParameters model with the rabbitmq information. This is the same as the one in the charm state, as that library is just use in this project.

A refactor has been done, moving most of the code related to integrations from charm.py, databases.py and charm_state.py to charm_integrations.py. The integrations are managed now by the class paas_app_charmer.charm_integrations.Integrations, that is in charge of registering all integrations, checking if there are missing integrations and also in creating the IntegrationsState instance (part of the CharmState).

Each one of the integrations are subclasses of Integration, so they all contain register and is_ready methods, and are handled in a similar way. Each of these integrations can create its own part of the charm state for the integration (before this code was in charm_state.py). This code may require further improvements in future PRs.

Rationale

Juju Events Changes

Module Changes

Library Changes

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing 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)

[github-actions]

Test coverage for b8fe43c

Name                                            Stmts   Miss Branch BrPart  Cover   Missing
-------------------------------------------------------------------------------------------
paas_app_charmer/__init__.py                       39     18      0      0    54%   17-18, 23-24, 30-31, 37-38, 44-45, 51-52, 58-59, 66-67, 72-73
paas_app_charmer/_gunicorn/__init__.py              0      0      0      0   100%
paas_app_charmer/_gunicorn/charm.py                15      0      0      0   100%
paas_app_charmer/_gunicorn/webserver.py            83      4     16      1    95%   175, 187-193
paas_app_charmer/_gunicorn/workload_config.py       8      0      0      0   100%
paas_app_charmer/_gunicorn/wsgi_app.py             16      0      0      0   100%
paas_app_charmer/app.py                           126      1     52      3    98%   95->exit, 145->151, 289
paas_app_charmer/charm.py                         133     14     18      4    87%   140-141, 143-144, 165->exit, 177-181, 205-207, 253-254, 259, 264
paas_app_charmer/charm_integrations.py            173      7     39      2    96%   245, 273-274, 359-360, 494-495
paas_app_charmer/charm_state.py                    87      1     10      1    98%   166
paas_app_charmer/charm_utils.py                    23      0      0      0   100%
paas_app_charmer/database_migration.py             35      0      2      0   100%
paas_app_charmer/django/__init__.py                 2      0      0      0   100%
paas_app_charmer/django/charm.py                   34      4      6      2    85%   44, 81, 96-97
paas_app_charmer/exceptions.py                      5      0      0      0   100%
paas_app_charmer/fastapi/__init__.py                2      0      0      0   100%
paas_app_charmer/fastapi/charm.py                  29      0      0      0   100%
paas_app_charmer/flask/__init__.py                  2      0      0      0   100%
paas_app_charmer/flask/charm.py                    24      0      0      0   100%
paas_app_charmer/go/__init__.py                     2      0      0      0   100%
paas_app_charmer/go/charm.py                       26      0      0      0   100%
paas_app_charmer/observability.py                  20      0      6      1    96%   41->45
paas_app_charmer/rabbitmq.py                       76      1     24      4    95%   116->exit, 151->exit, 156, 175->169
paas_app_charmer/secret_storage.py                 50      3     16      5    88%   51, 55->54, 56->58, 86, 105
paas_app_charmer/utils.py                          21      4     14      2    71%   30, 32, 52-53
-------------------------------------------------------------------------------------------
TOTAL                                            1031     57    203     25    93%

Static code analysis report

Run started:2024-09-05 13:04:12.743396

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 2284
  Total lines skipped (#nosec): 1
  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):

[jdkandersson]

Does it have to be called this?

[javierdelapuente]

I will update to rabbitmq in the other pr. The reason for that was because that was the name in rabbitmq-server (and amqp is the protocol)

[jdkandersson]

Shouldn't we just say run fetch-libs?

[jdkandersson]

I don't think I like it, I propose we go with the if-else ladder for now and get advice from @tonyandrewmeyer from the ops team on how to reduce it

[jdkandersson]

We can't do this because it takes away the option of the charm developer customising the code. All the observe need to be here and all the functions need to be defined on the class so that an adventurous Flask developer can change how they work and still be able to use the machinery we have built

[javierdelapuente]

Sure, we can go without the refactor (I have it in the other PR).

However, I do not see why that would limit a user, everything can be overridden as it was before...

[javierdelapuente]

(talked outside here) the reason is that there is only one callback function for all of the integrations

[tonyandrewmeyer]

It sounds like this is resolved now, but let me know if you'd still like input on anything :)

[javierdelapuente]

closing the PR for now.