[feature] Implement SNMP check #297

[purhan]

Closes #297

Checks:

• I have manually tested the proposed changes
• I have written new test cases to avoid regressions (if necessary)
• I have updated the documentation (e.g. README.rst)

[nemesifier]

There are conflicts with the base branch as well.

[pandafy]

Good work @purhan! Can you please answer to my following queries?

[coveralls]

Coverage increased (+0.03%) to 98.936% when pulling aaad59a on issues/297-snmp-check into abd9165 on master.

[pandafy]

Interface information of the device is not shown on in device status page. I think the culprit is the following code:

openwisp-monitoring/openwisp_monitoring/device/base/models.py

Lines 80 to 82 in 3d094ac

	# don't show interfaces if they don't have any useful info
	if len(interface.keys()) <= 2:
	continue

@purhan please ensure that information about interfaces is displayed

[purhan]

Interface information of the device is not shown on in device status page. I think the culprit is the following code:

openwisp-monitoring/openwisp_monitoring/device/base/models.py

Lines 80 to 82 in 3d094ac

	# don't show interfaces if they don't have any useful info
	if len(interface.keys()) <= 2:
	continue

@purhan please ensure that information about interfaces is displayed

@pandafy Thanks! I found out the problem in netengine and fixed it in this commit. It should be working now, we don't need to change anything here

[nemesifier]

Good progress! See my comments below.

[nemesifier]

It's not very clear to me how OpenWrt or AirOS is chosen

[purhan]

@nemesisdesign We are selecting a class from Netengine based on the type of connector. It's like a switch-case statement.

[nemesifier]

@pandafy we can still add a setting later if we feel it can really be useful, at this stage it's not so urgent, right?

[nemesifier]

During our testing we noticed that the CPU load chart is not laoded for AirOS, can you please fix this?

[purhan]

During our testing we noticed that the CPU load chart is not laoded for AirOS, can you please fix this?

@nemesisdesign This was done in openwisp/netengine@5424532

[Aryamanz29]

I need to increase coverage.

[Aryamanz29]

@nemesisdesign The coverage is reduced due to absence of test_auto_check_creation -> SNMP auto subtest (which I later added), So I tried various methods to set AUTO_SNMP = True in check/tests/test_models.py using @patch() / @patch_objects() /@override_settings() , They indeed set AUTO_SNMP to True but before calling post_save.connect() (checks/apps.py) AUTO_SNMP always False due to which check never created.

See below:

# check/tests/test_models.py

@patch('openwisp_monitoring.check.settings.AUTO_SNMP', True)
    def test_auto_check_creation(self):
        self.assertEqual(Check.objects.count(), 0)
        d = self._create_device(organization=self._create_org())
        print(app_settings.__dict__)
        print(Check.objects.all())
        # check is automatically created via django signal
        self.assertEqual(Check.objects.count(), 3) # It should have Ping, Config Applied & SNMP
        ... ...
        ... ...
        with self.subTest('Test AUTO_SNMP'):
            c3 = Check.objects.filter(check_type=self._SNMP_DEVICEMONITORING).first()
            self.assertEqual(c3.content_object, d)
            self.assertEqual(self._SNMP_DEVICEMONITORING, c3.check_type)

print(f'Value of AUTO_SNMP = {app_settings.AUTO_SNMP}')
        if app_settings.AUTO_SNMP:
        ...
        ...
print(app_settings.__dict__)
print(Check.objects.all())

# output

Value of AUTO_SNMP = False # Because of this snmp signal not called and check not created

... ... ... 'AUTO_PING': True, 'AUTO_CONFIG_CHECK': True, 'AUTO_SNMP': True, 'MANAGEMENT_IP_ONLY': False, 'PING_CHECK_CONFIG': {}}

<QuerySet [<Check: Ping (Device: default.test.device)>, <Check: Configuration Applied (Device: default.test.device)>]>

AssertionError: 2 != 3

----------------------------------------------------------------------
Ran 1 test in 0.092s

FAILED (failures=1)

Current possible solution :

• Set AUTO_SNMP directly in openwisp-monitoring/tests/openwisp2/settings.py
• Made required changes in broken tests aaad59a.

# settings.py 
if TESTING:
    ...
    ...
    # for testing AUTO_SNMP
    OPENWISP_MONITORING_AUTO_SNMP = True