Add Support for Dynamic Settings

[rochacbruno]

Issue: AAH-2009

Feature is deactivated by default,
to activate Requires Dynaconf 3.2.2

What this PR is doing?

1. This PR adds a new table to the models config.Setting, this table will store key:value pairs to be dynamically added to Dynaconf data and be available through django.conf.settings
   IMPORTANT key/value are stores in the database as str, upon access value can be read raw or parsed by dynaconf/toml, model also stores a timestamp

2. Along with the model, the PR also adds a schema on dynamic_settings.py:DYNACMIC_SETTINGS_SCHEMA which defines which keys can be stored on the database, as we cannot allow all settings to be dynamic.

3. A management command django-admin galaxy-settings is also added with commands to set,get,delete,list,inspect the settings on the database.

4. Every time a Setting is mutated on database it will also update a cache on Redis, if Redis is not available then caching will be skipped (and logged)

5. Finally, the PR adds a Dynaconf method hook to the dynaconf:Settings:get method, making access to any variables listed on the schema to trigger an immediate lookup on cache -> db IMPORTANT this last feature requires Dynaconf 3.2.2 (to be released)

NOTE The PR can be merged before Dynaconf 3.2.2 is released, there will be no breaking, only the feature n 5 will not be enabled.

6. This PR adds a new variable to settings.py GALAXY_DYNAMIC_SETTINGS=False this is the main toggle for the feature n 5, this is by default set to False, which means, django.conf.settings will lookup for keys in the cache/db only if this is set to True.

How to add settings to the database?

django-admin galaxy-settings set --key=GALAXY_FEATURE_FLAGS__power_mode --value=true
django-admin galaxy-settings get --key GALAXY_FEATURE_FLAGS 

More details on django-admin galaxy-settings --help

Or via script/shell

from galaxy_ng.app.models.config import Setting
Setting.set_value_in_db("GALAXY_FEATURE_FLAGS", "@merge power_mode=true")
#or equivalent 
Setting.set_value_in_db("GALAXY_FEATURE_FLAGS__power_mode", "true")

Currently there is no API (WIP) so command and script is the only way to manage the settings.

Due to the validation, it is not recommended to write directly to the database.

How to read settings from database with current version of dynaconf?

from galaxy_ng.app.models.config import Setting
result = Setting.get("GALAXY_FEATURE_FLAGS")
# Will lookup DB and then merge with current django/dynaconf settings
# before returning the result

How to read settings from db/cache after the upgrade to Dynaconf 3.2.2

1st enable GALAXY_DYNAMIC_SETTINGS=True via settings.py or PULP_ prefixed envvar.

then access settings normally using django.

from django.conf import settings
result = settings.GALAXY_FEATURE_FLAGS  
# upon access to key listed on DYNAMIC_SETTINGS_SCHEMA
# dynaconf will magically lookup on cache/db to merge data
# before returning the result.

What about the API/UI?

• API will be added in another PR
• UI will be created based on DYNAMIC_SETTINGS_SCHEMA and will be added after the API

[rochacbruno]

/retest

[slemrmartin]

👍 Awesome work