Closes #10945: Enable recurring execution of scheduled reports & scripts (#11096)

* Add interval to JobResult

* Accept a recurrence interval when executing scripts & reports

* Cleaned up jobs list display

* Schedule next job only if a reference start time can be determined

* Improve validation for scheduled jobs

netbox/extras/forms/scripts.py

@@ -1,4 +1,5 @@
 from django import forms
+from django.utils import timezone
 from django.utils.translation import gettext as _
 
 from utilities.forms import BootstrapMixin, DateTimePicker
@@ -21,19 +22,36 @@ class ScriptForm(BootstrapMixin, forms.Form):
         label=_("Schedule at"),
         help_text=_("Schedule execution of script to a set time"),
     )
+    _interval = forms.IntegerField(
+        required=False,
+        min_value=1,
+        label=_("Recurs every"),
+        help_text=_("Interval at which this script is re-run (in minutes)")
+    )
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
         # Move _commit and _schedule_at to the end of the form
         schedule_at = self.fields.pop('_schedule_at')
+        interval = self.fields.pop('_interval')
         commit = self.fields.pop('_commit')
         self.fields['_schedule_at'] = schedule_at
+        self.fields['_interval'] = interval
         self.fields['_commit'] = commit
 
+    def clean__schedule_at(self):
+        scheduled_time = self.cleaned_data['_schedule_at']
+        if scheduled_time and scheduled_time < timezone.now():
+            raise forms.ValidationError({
+                '_schedule_at': _('Scheduled time must be in the future.')
+            })
+
+        return scheduled_time
+
     @property
     def requires_input(self):
         """
-        A boolean indicating whether the form requires user input (ignore the _commit and _schedule_at fields).
+        A boolean indicating whether the form requires user input (ignore the built-in fields).
         """
-        return bool(len(self.fields) > 2)
+        return bool(len(self.fields) > 3)