Divide by zero error with very low power feed values #3905

hSaria · 2020-01-13T13:41:56Z

Environment

Python version: 3.6.8
NetBox version: 2.6.11

Steps to Reproduce

Create power feed with voltage, amperage, and max utilization set to 1
Create device with a power port with no power attributes (e.g. maximum_draw) that connects to the power feed created in step 1
Browse to the power feed details page

Expected Behavior

Page loads

Observed Behavior

ZeroDivisionError exception because the percentage calculation is using available_power which was rounded to 0 with

self.voltage * self.amperage * (self.max_utilization / 100) =
1            * 1             * 0.01                         = 0.01

The text was updated successfully, but these errors were encountered:

jeremystretch · 2020-01-13T14:24:17Z

I'm not able to replicate this on v2.6.11. The PowerFeed is created as expected:

Can you post the full stack trace please?

hSaria · 2020-01-13T14:26:05Z

Environment:


Request Method: GET
Request URL: http://netbox/dcim/power-feeds/2/

Django Version: 2.2.8
Python Version: 3.6.8
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'django.contrib.humanize',
 'cacheops',
 'corsheaders',
 'debug_toolbar',
 'django_filters',
 'django_tables2',
 'django_prometheus',
 'mptt',
 'rest_framework',
 'taggit',
 'taggit_serializer',
 'timezone_field',
 'circuits',
 'dcim',
 'ipam',
 'extras',
 'secrets',
 'tenancy',
 'users',
 'utilities',
 'virtualization',
 'drf_yasg']
Installed Middleware:
('debug_toolbar.middleware.DebugToolbarMiddleware',
 'django_prometheus.middleware.PrometheusBeforeMiddleware',
 'corsheaders.middleware.CorsMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware',
 'django.middleware.security.SecurityMiddleware',
 'utilities.middleware.ExceptionHandlingMiddleware',
 'utilities.middleware.LoginRequiredMiddleware',
 'utilities.middleware.APIVersionMiddleware',
 'extras.middleware.ObjectChangeMiddleware',
 'django_prometheus.middleware.PrometheusAfterMiddleware')


Template error:
In template /opt/netbox-2.6.11/netbox/templates/_base.html, error at line 0
   division by zero
   1 : {% load static %}
   2 : {% load helpers %}
   3 : <!DOCTYPE html>
   4 : <html lang="en">
   5 : <head>
   6 :     <title>{% block title %}Home{% endblock %} - NetBox</title>
   7 :     <link rel="stylesheet" href="{% static 'bootstrap-3.4.1-dist/css/bootstrap.min.css' %}">
   8 :     <link rel="stylesheet" href="{% static 'font-awesome-4.7.0/css/font-awesome.min.css' %}">
   9 :     <link rel="stylesheet" href="{% static 'jquery-ui-1.12.1/jquery-ui.css' %}">
   10 :     <link rel="stylesheet" href="{% static 'select2-4.0.5/css/select2.min.css' %}">


Traceback:

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)

File "/usr/local/lib/python3.6/site-packages/django/contrib/auth/mixins.py" in dispatch
  85.         return super().dispatch(request, *args, **kwargs)

File "/usr/local/lib/python3.6/site-packages/django/views/generic/base.py" in dispatch
  97.         return handler(request, *args, **kwargs)

File "/opt/netbox-2.6.11/netbox/dcim/views.py" in get
  2373.             'powerfeed': powerfeed,

File "/usr/local/lib/python3.6/site-packages/django/shortcuts.py" in render
  36.     content = loader.render_to_string(template_name, context, request, using=using)

File "/usr/local/lib/python3.6/site-packages/django/template/loader.py" in render_to_string
  62.     return template.render(context, request)

File "/usr/local/lib/python3.6/site-packages/django/template/backends/django.py" in render
  61.             return self.template.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  171.                     return self._render(context)

File "/usr/local/lib/python3.6/site-packages/django/test/utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/loader_tags.py" in render
  150.             return compiled_parent._render(context)

File "/usr/local/lib/python3.6/site-packages/django/test/utils.py" in instrumented_test_render
  96.     return self.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/loader_tags.py" in render
  62.                 result = block.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/defaulttags.py" in render
  513.             return self.nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/defaulttags.py" in render
  309.                 return nodelist.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render
  937.                 bit = node.render_annotated(context)

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in render_annotated
  904.             return self.render(context)

File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in render
  213.         resolved_args, resolved_kwargs = self.get_resolved_arguments(context)

File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in get_resolved_arguments
  177.         resolved_args = [var.resolve(context) for var in self.args]

File "/usr/local/lib/python3.6/site-packages/django/template/library.py" in <listcomp>
  177.         resolved_args = [var.resolve(context) for var in self.args]

File "/usr/local/lib/python3.6/site-packages/django/template/base.py" in resolve
  698.                 new_obj = func(obj, *arg_vals)

File "/opt/netbox-2.6.11/netbox/utilities/templatetags/helpers.py" in percentage
  192.     return round(x / y * 100)

Exception Type: ZeroDivisionError at /dcim/power-feeds/2/
Exception Value: division by zero

hSaria · 2020-01-13T14:28:16Z

@jeremystretch Yeah, I just tried to recreate this with a new database and it doesn't occur. Let me see what I did differently.

hSaria · 2020-01-13T14:35:12Z

@jeremystretch updated the steps.

Fixes #3905: divide by zero on power feeds with low values

hSaria · 2020-01-14T11:20:42Z

@jeremystretch so I found out that this is also happening on the devices view (assign one of the power ports to a power feed. Shall I just keep chasing those down with if conditions or just change the percentage filter to return 0 if the denominator is 0?

Math people, please don't hurt me. I know diving by 0 is not equal to 0; just trying to avoid an exception here.

jeremystretch · 2020-01-14T13:46:07Z

@hSaria Let's try to catch all the occurrences. IMO I think I'd rather know when we're dividing by zero than suppress the error.

hSaria mentioned this issue Jan 13, 2020

Fixes #3905: divide by zero on power feeds with low values #3906

Merged

jeremystretch added the status: revisions needed This issue requires additional information to be actionable label Jan 13, 2020

jeremystretch added status: accepted This issue has been accepted for implementation type: bug A confirmed report of unexpected behavior in the application and removed status: revisions needed This issue requires additional information to be actionable labels Jan 13, 2020

jeremystretch closed this as completed in #3906 Jan 13, 2020

jeremystretch added a commit that referenced this issue Jan 13, 2020

Merge pull request #3906 from hSaria/3905-powerfeed-divide-by-zero

0f42219

Fixes #3905: divide by zero on power feeds with low values

jeremystretch mentioned this issue Jan 13, 2020

Release v2.6.12 #3908

Merged

lock bot locked as resolved and limited conversation to collaborators Apr 15, 2020

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Divide by zero error with very low power feed values #3905

Divide by zero error with very low power feed values #3905

hSaria commented Jan 13, 2020 •

edited

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jeremystretch commented Jan 13, 2020

hSaria commented Jan 13, 2020

hSaria commented Jan 13, 2020

hSaria commented Jan 13, 2020

hSaria commented Jan 14, 2020

jeremystretch commented Jan 14, 2020

Divide by zero error with very low power feed values #3905

Divide by zero error with very low power feed values #3905

Comments

hSaria commented Jan 13, 2020 • edited Loading

Environment

Steps to Reproduce

Expected Behavior

Observed Behavior

jeremystretch commented Jan 13, 2020

hSaria commented Jan 13, 2020

hSaria commented Jan 13, 2020

hSaria commented Jan 13, 2020

hSaria commented Jan 14, 2020

jeremystretch commented Jan 14, 2020

hSaria commented Jan 13, 2020 •

edited

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