Control maintenance mode via DB

[jordmantheman]

(feature request)

Using a text file on the host doesn't work for django installations that distribute requests across multiple hosts. It seems like more of a detriment of the library to avoid using tables for this control than a benefit. Are the maintainers philosophically against this, or was it just a more expensive implementation than the sentinel file approach?

[fabiocaccamo]

@jordmantheman I know this limit, I thinks there could be 2 different ways to implement this new feature:

• Implement a small model/admin internally to the lib.

• Expose 2 new settings: MAINTENANCE_MODE_STATE_GETTER and MAINTENANCE_MODE_STATE_SETTER where it is possibile to define custom functions that implements the db read/write logic. This approach is the more flexible one.

[fabiocaccamo]

@jordmantheman which of the two options described above would you prefere?

[spapas]

One extra thing to consider is to allow the users to use redis (if it is present for cache) instead of the database; querying redis for a true/false value is faster than querying the database.

The MAINTENANCE_MODE_STATE_GETTER you propose could probably be used for that (requiring the user to actually write the put/get code in the database) but I believe that it would be better to actually provide a buch of MAINTENANCE_MODE_STATE_GETTER for the user to use (probably two would be enough, one for the database and one for the redis backend similar to how django-constance backends work).

[jordmantheman]

Sorry for the delay!

Having configurable setters/getters is probably best. Agree w/ @spapas that a couple of baked in implementations could be useful. Perhaps an implementation using django-cache (assuming an in-memory store isn't used) would be a useful abstraction for someone using redis.

[fabiocaccamo]

Added pluggable backends support in 0.12.0 version, enjoy :).

[fabiocaccamo]

Just implement your custom backend extending AbstractStateBackend:

import maintenance_mode.backends.AbstractStateBackend


class MaintenanceModeCustomBackend(AbstractStateBackend):

    def get_value(self):
		value = False
		# get the value here and return it
        return value

    def set_value(self, value):
        # store value
		pass

Then in settipgs.py set your custom backend class path:

MAINTENANCE_MODE_STATE_BACKEND = 'myapp.backends.MaintenanceModeCustomBackend'

[adremides]

Can please provide an example how to implmenent db way to switch maintenance mode on/off with a custom backend?

[fabiocaccamo]

@adremides you just need to:

• create your own backend extending the abstract backend
• override the get_value and set_value methods (to get and set the state value as you need)
• set your backend as the default one using settings settings.MAINTENANCE_MODE_STATE_BACKEND

[adremides]

• override the get_value and set_value methods (to get and set the state value as you need)

I have trouble figuring it out how to do that. How do I override those methods to write the value state to a field in the database?

[fabiocaccamo]

@adremides you can see existing backends to understand how to override a method.
Concerning how to read/write a model field value the django documentation is very good:

• https://docs.djangoproject.com/en/3.2/ref/models/instances/
• https://docs.djangoproject.com/en/3.2/ref/models/fields/#booleanfield

[adremides]

I will expand your instructions with an example of how I finally did this:

• create your own backend extending the abstract backend:

  Inside of the app directory (in my case 'website'), create a folder called backends, inside of it create maintenance.py.

• set your backend as the default one using settings settings.MAINTENANCE_MODE_STATE_BACKEND:

  In settings added MAINTENANCE_MODE_STATE_BACKEND = 'website.backends.maintenance.MaintenanceModeCustomBackend'

• override the get_value and set_value methods (to get and set the state value as you need)

  My goal was to add maintenance mode in CodeRedCMS, so in the Settings area I created a new Category called
  MaintenanceModeSettings and inside of it a field called active (which is a Boolean):

# wagtailsettings_models.py
# ...
@register_setting(icon='fa-wrench')
class MaintenanceModeSettings(BaseSetting):
    """
    Maintenance Mode configuration.
    """
    class Meta:
        verbose_name = _('Maintenance Mode')

    active = models.BooleanField(
        default=False,
        verbose_name=_('Active'),
        help_text=_('Deactivate/Activate Maintenance Mode'),
    )

    panels = [
        MultiFieldPanel(
            [
                FieldPanel('active'),
            ],
            _('Maintenance Mode'),
        )
    ]
# ...

then I used this to override get_value

# maintenance.py
from maintenance_mode.backends import AbstractStateBackend
from wagtail.core.models import Site
from coderedcms.models.wagtailsettings_models import MaintenanceModeSettings


class MaintenanceModeCustomBackend(AbstractStateBackend):

    def get_value(self):
        maintenance_mode = MaintenanceModeSettings.for_site(
            Site.objects.get(is_default_site=True)
        ).active
        return maintenance_mode

    def set_value(self, value):
        raise NotImplementedError()