Closes #16971: Add system jobs (#17716)

* Fix check for existing jobs

If a job is to be enqueued once and no specific scheduled time is
specified, any scheduled time of existing jobs will be valid. Only if a
specific scheduled time is specified for 'enqueue_once()' can it be
evaluated.

* Allow system jobs to be registered

A new registry key allows background system jobs to be registered and
automatically scheduled when rqworker starts.

* Test scheduling of system jobs

* Fix plugins scheduled job documentation

The documentation reflected a non-production state of the JobRunner
framework left over from development. Now a more practical example
demonstrates the usage.

* Allow plugins to register system jobs

* Rename system job metadata

To clarify which meta-attributes belong to system jobs, each of them is
now prefixed with 'system_'.

* Add predefined job interval choices

* Remove 'system_enabled' JobRunner attribute

Previously, the 'system_enabled' attribute was used to control whether a
job should run or not. However, this can also be accomplished by
evaluating the job's interval.

* Fix test

* Use a decorator to register system jobs

* Specify interval when registering system job

* Update documentation

---------

Co-authored-by: Jeremy Stretch <jstretch@netboxlabs.com>

docs/plugins/development/background-jobs.md

@@ -29,6 +29,9 @@ class MyTestJob(JobRunner):
 
 You can schedule the background job from within your code (e.g. from a model's `save()` method or a view) by calling `MyTestJob.enqueue()`. This method passes through all arguments to `Job.enqueue()`. However, no `name` argument must be passed, as the background job name will be used instead.
 
+!!! tip
+    A set of predefined intervals is available at `core.choices.JobIntervalChoices` for convenience.
+
 ### Attributes
 
 `JobRunner` attributes are defined under a class named `Meta` within the job. These are optional, but encouraged.
@@ -46,26 +49,52 @@ As described above, jobs can be scheduled for immediate execution or at any late
 
 #### Example
 
+```python title="models.py"
+from django.db import models
+from core.choices import JobIntervalChoices
+from netbox.models import NetBoxModel
+from .jobs import MyTestJob
+
+class MyModel(NetBoxModel):
+    foo = models.CharField()
+
+    def save(self, *args, **kwargs):
+        MyTestJob.enqueue_once(instance=self, interval=JobIntervalChoices.INTERVAL_HOURLY)
+        return super().save(*args, **kwargs)
+
+    def sync(self):
+        MyTestJob.enqueue(instance=self)
+```
+
+
+### System Jobs
+
+Some plugins may implement background jobs that are decoupled from the request/response cycle. Typical use cases would be housekeeping tasks or synchronization jobs. These can be registered as _system jobs_ using the `system_job()` decorator. The job interval must be passed as an integer (in minutes) when registering a system job. System jobs are scheduled automatically when the RQ worker (`manage.py rqworker`) is run.
+
+#### Example
+
 ```python title="jobs.py"
-from netbox.jobs import JobRunner
+from core.choices import JobIntervalChoices
-
+from netbox.jobs import JobRunner, system_job
+from .models import MyModel
 
+# Specify a predefined choice or an integer indicating
+# the number of minutes between job executions
+@system_job(interval=JobIntervalChoices.INTERVAL_HOURLY)
 class MyHousekeepingJob(JobRunner):
     class Meta:
-        name = "Housekeeping"
+        name = "My Housekeeping Job"
 
     def run(self, *args, **kwargs):
-        # your logic goes here
+        MyModel.objects.filter(foo='bar').delete()
+
+system_jobs = (
+    MyHousekeepingJob,
+)
 ```
 
-```python title="__init__.py"
+!!! note
-from netbox.plugins import PluginConfig
+    Ensure that any system jobs are imported on initialization. Otherwise, they won't be registered. This can be achieved by extending the PluginConfig's `ready()` method.
-
-class MyPluginConfig(PluginConfig):
-    def ready(self):
-        from .jobs import MyHousekeepingJob
-        MyHousekeepingJob.setup(interval=60)
-```
 
 ## Task queues
 

docs/plugins/development/data-backends.md

@@ -18,6 +18,6 @@ backends = [MyDataBackend]
 ```
 
 !!! tip
-    The path to the list of search indexes can be modified by setting `data_backends` in the PluginConfig instance.
+    The path to the list of data backends can be modified by setting `data_backends` in the PluginConfig instance.
 
 ::: netbox.data_backends.DataBackend

netbox/core/choices.py

@@ -72,6 +72,20 @@ class JobStatusChoices(ChoiceSet):
     )
 
 
+class JobIntervalChoices(ChoiceSet):
+    INTERVAL_MINUTELY = 1
+    INTERVAL_HOURLY = 60
+    INTERVAL_DAILY = 60 * 24
+    INTERVAL_WEEKLY = 60 * 24 * 7
+
+    CHOICES = (
+        (INTERVAL_MINUTELY, _('Minutely')),
+        (INTERVAL_HOURLY, _('Hourly')),
+        (INTERVAL_DAILY, _('Daily')),
+        (INTERVAL_WEEKLY, _('Weekly')),
+    )
+
+
 #
 # ObjectChanges
 #

netbox/core/management/commands/rqworker.py

@@ -2,6 +2,8 @@ import logging
 
 from django_rq.management.commands.rqworker import Command as _Command
 
+from netbox.registry import registry
+
 
 DEFAULT_QUEUES = ('high', 'default', 'low')
 
@@ -14,6 +16,15 @@ class Command(_Command):
     of only the 'default' queue).
     """
     def handle(self, *args, **options):
+        # Setup system jobs.
+        for job, kwargs in registry['system_jobs'].items():
+            try:
+                interval = kwargs['interval']
+            except KeyError:
+                raise TypeError("System job must specify an interval (in minutes).")
+            logger.debug(f"Scheduling system job {job.name} (interval={interval})")
+            job.enqueue_once(**kwargs)
+
         # Run the worker with scheduler functionality
         options['with_scheduler'] = True
 

netbox/netbox/jobs.py

@@ -2,6 +2,7 @@ import logging
 from abc import ABC, abstractmethod
 from datetime import timedelta
 
+from django.core.exceptions import ImproperlyConfigured
 from django.utils.functional import classproperty
 from django_pglocks import advisory_lock
 from rq.timeouts import JobTimeoutException
@@ -9,12 +10,30 @@ from rq.timeouts import JobTimeoutException
 from core.choices import JobStatusChoices
 from core.models import Job, ObjectType
 from netbox.constants import ADVISORY_LOCK_KEYS
+from netbox.registry import registry
 
 __all__ = (
     'JobRunner',
+    'system_job',
 )
 
 
+def system_job(interval):
+    """
+    Decorator for registering a `JobRunner` class as system background job.
+    """
+    if type(interval) is not int:
+        raise ImproperlyConfigured("System job interval must be an integer (minutes).")
+
+    def _wrapper(cls):
+        registry['system_jobs'][cls] = {
+            'interval': interval
+        }
+        return cls
+
+    return _wrapper
+
+
 class JobRunner(ABC):
     """
     Background Job helper class.
@@ -129,7 +148,7 @@ class JobRunner(ABC):
         if job:
             # If the job parameters haven't changed, don't schedule a new job and keep the current schedule. Otherwise,
             # delete the existing job and schedule a new job instead.
-            if (schedule_at and job.scheduled == schedule_at) and (job.interval == interval):
+            if (not schedule_at or job.scheduled == schedule_at) and (job.interval == interval):
                 return job
             job.delete()
 

netbox/netbox/registry.py

@@ -30,6 +30,7 @@ registry = Registry({
     'models': collections.defaultdict(set),
     'plugins': dict(),
     'search': dict(),
+    'system_jobs': dict(),
     'tables': collections.defaultdict(dict),
     'views': collections.defaultdict(dict),
     'widgets': dict(),

netbox/netbox/tests/dummy_plugin/__init__.py

@@ -21,5 +21,10 @@ class DummyPluginConfig(PluginConfig):
         'netbox.tests.dummy_plugin.events.process_events_queue'
     ]
 
+    def ready(self):
+        super().ready()
+
+        from . import jobs  # noqa: F401
+
 
 config = DummyPluginConfig

netbox/netbox/tests/dummy_plugin/jobs.py

@@ -0,0 +1,9 @@
+from core.choices import JobIntervalChoices
+from netbox.jobs import JobRunner, system_job
+
+
+@system_job(interval=JobIntervalChoices.INTERVAL_HOURLY)
+class DummySystemJob(JobRunner):
+
+    def run(self, *args, **kwargs):
+        pass

netbox/netbox/tests/test_jobs.py

@@ -90,6 +90,15 @@ class EnqueueTest(JobRunnerTestCase):
         self.assertEqual(job1, job2)
         self.assertEqual(TestJobRunner.get_jobs(instance).count(), 1)
 
+    def test_enqueue_once_twice_same_no_schedule_at(self):
+        instance = DataSource()
+        schedule_at = self.get_schedule_at()
+        job1 = TestJobRunner.enqueue_once(instance, schedule_at=schedule_at)
+        job2 = TestJobRunner.enqueue_once(instance)
+
+        self.assertEqual(job1, job2)
+        self.assertEqual(TestJobRunner.get_jobs(instance).count(), 1)
+
     def test_enqueue_once_twice_different_schedule_at(self):
         instance = DataSource()
         job1 = TestJobRunner.enqueue_once(instance, schedule_at=self.get_schedule_at())
@@ -127,3 +136,30 @@ class EnqueueTest(JobRunnerTestCase):
         self.assertNotEqual(job1, job2)
         self.assertRaises(Job.DoesNotExist, job1.refresh_from_db)
         self.assertEqual(TestJobRunner.get_jobs(instance).count(), 1)
+
+
+class SystemJobTest(JobRunnerTestCase):
+    """
+    Test that system jobs can be scheduled.
+
+    General functionality already tested by `JobRunnerTest` and `EnqueueTest`.
+    """
+
+    def test_scheduling(self):
+        # Can job be enqueued?
+        job = TestJobRunner.enqueue(schedule_at=self.get_schedule_at())
+        self.assertIsInstance(job, Job)
+        self.assertEqual(TestJobRunner.get_jobs().count(), 1)
+
+        # Can job be deleted again?
+        job.delete()
+        self.assertRaises(Job.DoesNotExist, job.refresh_from_db)
+        self.assertEqual(TestJobRunner.get_jobs().count(), 0)
+
+    def test_enqueue_once(self):
+        schedule_at = self.get_schedule_at()
+        job1 = TestJobRunner.enqueue_once(schedule_at=schedule_at)
+        job2 = TestJobRunner.enqueue_once(schedule_at=schedule_at)
+
+        self.assertEqual(job1, job2)
+        self.assertEqual(TestJobRunner.get_jobs().count(), 1)

netbox/netbox/tests/test_plugins.py

@@ -5,8 +5,10 @@ from django.core.exceptions import ImproperlyConfigured
 from django.test import Client, TestCase, override_settings
 from django.urls import reverse
 
+from core.choices import JobIntervalChoices
 from netbox.tests.dummy_plugin import config as dummy_config
 from netbox.tests.dummy_plugin.data_backends import DummyBackend
+from netbox.tests.dummy_plugin.jobs import DummySystemJob
 from netbox.plugins.navigation import PluginMenu
 from netbox.plugins.utils import get_plugin_config
 from netbox.graphql.schema import Query
@@ -130,6 +132,13 @@ class PluginTest(TestCase):
         self.assertIn('dummy', registry['data_backends'])
         self.assertIs(registry['data_backends']['dummy'], DummyBackend)
 
+    def test_system_jobs(self):
+        """
+        Check registered system jobs.
+        """
+        self.assertIn(DummySystemJob, registry['system_jobs'])
+        self.assertEqual(registry['system_jobs'][DummySystemJob]['interval'], JobIntervalChoices.INTERVAL_HOURLY)
+
     def test_queues(self):
         """
         Check that plugin queues are registered with the accurate name.