[feature] Implemented device deactivation and reactivation #625

[pandafy]

Closes #625

Blockers

• [change] Made admin/submit_line.html extendable openwisp-utils#370

TODOS

• we shall make all the field of a deactivated device readonly
• if the device has any related OpenVPN template with certificates, the certificates shall be flagged as revoked
• removes any config and template from the device, ensuring the revoked certificates do not get deleted (because we need those to be in the CRL)
• sets the config status to deactivating (this is a new status)
• once the config is applied by the agent (we must make sure it's deactivated) the config status should be set to "deactivated" instead of "modified"
• once the config is set to deactivated, the controller HTTP API should return 404 for these devices, so that the agent stops asking for the checksum
• I think we should hide the delete button of the admin and show "deactivate" instead, we could show the delete button only if the config status is "deactivated" or if the device does not have a config object
• we should add the deactivate admin list action, if we can add it before the delete action it's better
• the admin action which deactivates multiple items at once must deal with the case in which one or multiple devices are already deactivated in a graceful way, informing the user and without failing
• ensure we emit a signal when this happens, I believe a config status change is emitted but let's double check (so we can listen for this event in other modules)
• we will also need to update the API to prevent changing any details on the deactivated devices
• add an admin action which sets the config status to applied;
  • it must deal with the case in which one or multiple devices are already activated in graceful way, informing the user and without failing

[pandafy]

@nemesifier why do we need this? It is creating an issue for marking the device as deactivated. Instead of changing the status from deactivating to deactivated, this code is changing the status to applied. Can we rely on the report status request from the agent for this?

[nemesifier]

Agreed, proceed, there may be some test to change because of this removal.

[nemesifier]

#853

[nemesifier]

Looking good!

I did a quick code review, find my comments below.

Please let's take advantage to introduce the improvement discussed yesterday:

diff --git a/openwisp_controller/config/admin.py b/openwisp_controller/config/admin.py
index 764ae7f..cd573fb 100644
--- a/openwisp_controller/config/admin.py
+++ b/openwisp_controller/config/admin.py
@@ -641,6 +641,10 @@ class DeviceAdmin(MultitenantAdminMixin, BaseConfigAdmin, UUIDAdmin):
     ip.short_description = _('IP address')
 
     def config_status(self, obj):
+        if obj.is_deactivated:
+            return _('deactivated')
+        if not obj.config:
+            return _('unknown')
         return obj.config.status
 
     config_status.short_description = _('config status')

Another note:

Can we hide the save and save continue button on deactivated devices?

What else is missing?

• Do not allow to delete devices which are not deactivated first via admin action
• Admin inlines
• It would be great to show the readonly config value as indented JSON (now it shows OrderedDict(...)).

API changes:

• Disable API endpoints to make changes to deactivated devices
• I think we need to allow to enable and disable a device via API too, right?
  We could split the API changes in a separate issue but we need to discuss this first

Anything else?