Replace read_only and snmp_version Netbox attrs

Netbox shadow objects used to use the pseudo attributes `read_only` and
`snmp_version` to store the SNMP v1/v2c read-only community and SNMP
version.  On the Netbox Django model, these are computed properties,
based on the Netbox' preferred SNMP management profile, and have been
deprecated for a while.

Since ipdevpoll now needs to access more complicated SNMP management
configuration for a Netbox, this changes the Netbox shadow model to
store an SNMPParameters object directly, which will be populated from
the Netbox' preferred SNMP profile.

Usages of the removed attributes have been updated.  Usages mostly
concern themselves with verifying that a device actually has an SNMP
profile at all.

However, the ipdevpoll dataloader used the value of the pseudo
attributes to detect whether a Netbox' management credentials had
changed and needed to be reloaded from the database, and this patch does
not fully replace that.

This more or less fixes Uninett#2522

python/nav/ipdevpoll/__init__.py

@@ -77,7 +77,7 @@ def can_handle(cls, netbox):
         """
         snmp_up = getattr(netbox, 'snmp_up', True)
 
-        basic_req = netbox.is_up() and snmp_up and bool(netbox.read_only)
+        basic_req = netbox.is_up() and snmp_up and bool(netbox.snmp_parameters)
         vendor_check = cls._verify_vendor_restriction(netbox)
         return basic_req and vendor_check
 

python/nav/ipdevpoll/dataloader.py

@@ -176,12 +176,11 @@ def is_netbox_changed(netbox1, netbox2):
     for attr in (
         'ip',
         'type',
-        'read_only',
-        'snmp_version',
         'up',
         'snmp_up',
         'deleted_at',
     ):
+        # TODO Need some way to detect an updated SNMP profile
         if getattr(netbox1, attr) != getattr(netbox2, attr):
             _logger.debug(
                 "%s.%s changed from %r to %r",

python/nav/ipdevpoll/plugins/snmpcheck.py

@@ -44,14 +44,16 @@ class SnmpCheck(Plugin):
 
     @classmethod
     def can_handle(cls, netbox):
-        return netbox.is_up() and bool(netbox.read_only)
+        return netbox.is_up() and bool(netbox.snmp_parameters)
 
     def __init__(self, *args, **kwargs):
         super(SnmpCheck, self).__init__(*args, **kwargs)
 
     @defer.inlineCallbacks
     def handle(self):
-        self._logger.debug("snmp version from db: %s", self.netbox.snmp_version)
+        self._logger.debug(
+            "snmp version from db: %s", self.netbox.snmp_parameters.version
+        )
         was_down = yield db.run_in_thread(self._currently_down)
         is_ok = yield self._do_check()
 

python/nav/ipdevpoll/shadows/netbox.py

@@ -14,9 +14,12 @@
 # License along with NAV. If not, see <http://www.gnu.org/licenses/>.
 #
 """netbox related shadow classes"""
+from typing import Union
+
 from django.db.models import Q
 from django.db import transaction
 
+from nav.ipdevpoll.snmp.common import SNMPParameters
 from nav.models import manage
 from nav.ipdevpoll.storage import Shadow
 
@@ -29,13 +32,14 @@ class Netbox(Shadow):
     def __init__(self, *args, **kwargs):
         super(Netbox, self).__init__(*args, **kwargs)
         if args:
-            obj = args[0]
+            obj: Union[Netbox, manage.Netbox] = args[0]
             self.snmp_up = getattr(obj, 'snmp_up', not obj.is_snmp_down())
             self.last_updated = getattr(
                 obj, 'last_updated', self._translate_last_jobs(obj)
             )
-            self.read_only = getattr(obj, 'read_only')
-            self.snmp_version = getattr(obj, 'snmp_version')
+            self.snmp_parameters = getattr(obj, "snmp_parameters", {})
+            if not self.snmp_parameters:
+                self.snmp_parameters = SNMPParameters.factory(obj)
 
     @staticmethod
     def _translate_last_jobs(netbox):