Style Guide¶
Nautobot generally follows the Django style guide, which is itself based on PEP 8. The following tools are used to enforce coding style and best practices:
- Ruff is used to enforce code formatting conventions as well as perform code analysis.
- Pylint is used for Python static code analysis.
- Hadolint is used to lint and validate Docker best practices in the Dockerfile.
- MarkdownLint-cli is used to lint and validate Markdown (documentation) files.
Nautobot-specific configuration of these tools is maintained in the files .markdownlint.yml
or pyproject.toml
as appropriate to the individual tool.
It is strongly recommended to include all of the above tools as part of your commit process before opening any pull request. A Git commit hook is provided in the source at scripts/git-hooks/pre-commit
. Linking to this script from .git/hooks/
will invoke these tools prior to every commit attempt and abort if the validation fails.
You can also invoke these utilities manually against the development Docker containers by running:
or, as a single command:
Introducing New Dependencies¶
The introduction of a new dependency is best avoided unless it is absolutely necessary. For small features, it's generally preferable to replicate functionality within the Nautobot code base rather than to introduce reliance on an external project. This reduces both the burden of tracking new releases and our exposure to outside bugs and attacks.
If there's a strong case for introducing a new dependency, it must meet the following criteria:
- Its complete source code must be published and freely accessible without registration.
- Its license must be conducive to inclusion in an open source project.
- It must be actively maintained, with no longer than one year between releases.
- It must be available via the Python Package Index (PyPI).
New dependencies can be added to the project via the poetry add
command. This will correctly add the dependency to pyproject.toml
as well as the poetry.lock
file. You should then update the pyproject.toml
with a comment providing a short description of the package and/or how Nautobot is making use of it.
General Guidance¶
-
When in doubt, remain consistent: It is better to be consistently incorrect than inconsistently correct. If you notice in the course of unrelated work a pattern that should be corrected, continue to follow the pattern for now and open a bug so that the entire code base can be evaluated at a later point.
-
Prioritize readability over concision. Python is a very flexible language that typically offers several options for expressing a given piece of logic, but some may be more friendly to the reader than others. (List comprehensions are particularly vulnerable to over-optimization.) Always remain considerate of the future reader who may need to interpret your code without the benefit of the context within which you are writing it.
-
No easter eggs. While they can be fun, Nautobot must be considered as a business-critical tool. The potential, however minor, for introducing a bug caused by unnecessary logic is best avoided entirely.
-
Constants (variables which generally do not change) should be declared in
constants.py
within each app. -
Every model should have a docstring. Every custom method should include an explanation of its function.
-
The combination of
nautobot.core.filters.BaseFilterSet
,nautobot.extras.filters.CreatedUpdatedModelFilterSetMixin
,nautobot.extras.filters.CustomFieldModelFilterSetMixin
, andnautobot.extras.filters.RelationshipModelFilterSetMixin
is such a common use case throughout the code base that they have a helper class which combines all of these atnautobot.extras.NautobotFilterSet
. Use this helper class if you need the functionality from these classes. -
The combination of
nautobot.core.forms.BootstrapMixin
,nautobot.extras.forms.CustomFieldModelFormMixin
,nautobot.extras.forms.RelationshipModelFormMixin
andnautobot.extras.forms.NoteModelFormMixin
is such a common use case throughout the code base that they have a helper class which combines all of these atnautobot.extras.forms.NautobotModelForm
. Use this helper class if you need the functionality from these classes.
Added in version 1.4.0
-
Similarly, for filter forms,
nautobot.extras.forms.NautobotFilterForm
combinesnautobot.core.forms.BootstrapMixin
,nautobot.extras.forms.ContactTeamModelFilterFormMixin
(since Nautobot 2.3.0),nautobot.extras.forms.CustomFieldModelFilterFormMixin
, andnautobot.extras.forms.RelationshipModelFilterFormMixin
, and should be used where appropriate. -
Similarly, for bulk-edit forms,
nautobot.extras.forms.NautobotBulkEditForm
combinesnautobot.core.forms.BulkEditForm
andnautobot.core.forms.BootstrapMixin
withnautobot.extras.forms.CustomFieldModelBulkEditFormMixin
,nautobot.extras.forms.RelationshipModelBulkEditFormMixin
andnautobot.extras.forms.NoteModelBulkEditFormMixin
, and should be used where appropriate. -
API serializers for most models should inherit from
nautobot.extras.api.serializers.NautobotModelSerializer
and any appropriate mixins. Only use more abstract base classes such as ValidatedModelSerializer where absolutely required. -
NautobotModelSerializer
will automatically add serializer fields forid
,created
/last_updated
(if applicable),custom_fields
,computed_fields
, andrelationships
, so there's generally no need to explicitly declare these fields in.Meta.fields
of each serializer class. Similarly,TaggedModelSerializerMixin
and` will automatically add the
tagsand
status` fields when included in a serializer class. -
API Views for most models should inherit from
nautobot.extras.api.views.NautobotModelViewSet
. Only use more abstract base classes such asModelViewSet
where absolutely required.
Branding¶
- When referring to Nautobot in writing, use the proper form "Nautobot," with the letter N. The lowercase form "nautobot" should be used in code, filenames, etc.
- There is an SVG form of the Nautobot logo at nautobot/docs/nautobot_logo.svg. It is preferred to use this logo for all purposes as it scales to arbitrary sizes without loss of resolution. If a raster image is required, the SVG logo should be converted to a PNG image of the prescribed size.
Importing Python Packages¶
To prevent circular dependency errors and improve code readability, the following standards should be followed when importing from other python modules.
Tip
Some of the below rules will be applied automatically when running the ruff
linter/formatter against your code. Specifically, you can run invoke ruff --fix
to automatically reorder imports.
PEP8 Style Guide¶
Nautobot follows the PEP8 style guide's standard for importing modules. Libraries should be imported in these groups: standard library, third party libraries, then nautobot
packages and finally try/except imports. The groups should be separated by a single blank line. Within these groups,import lines should be sorted alphanumerically by the package name. Lists of of names imported from packages should also be sorted alphanumerically.
Example
Wildcard Imports¶
Wildcard imports (from foo import *
) should only be used in __init__.py
files to import names from submodules that have a __all__
variable defined.
Example
Importing from External Packages¶
Individual names may be imported from external packages (from foo import some_function, SomeClass
). This differs from the standard for importing from the nautobot
package.
Importing Nautobot Packages¶
Module Name Imports¶
Whenever possible, imports from the nautobot
package should use module level imports, not individual names from a module.
Example
Absolute Imports¶
Always use absolute imports instead of relative imports.
Example
Import Style Conventions¶
To import modules from other apps under the nautobot
namespace, use the convention from nautobot.<app_name> import <module> as <app_name>_<module>
. If importing from within the same app do not alias the imported namespace.
Example
Resolving Name Conflicts¶
When using external libraries you may need to import multiple different modules with the same name. In this case, the namespace from the external package should be aliased. For aliasing external libraries, use <package>_<module>
.
Example
Convenience Imports¶
Nautobot uses convenience imports in the same way that django implements them. These should be leveraged whenever possible.