OpenStack SDK Developer Coding Standards¶
We follow the coding guidelines of https://docs.openstack.org/hacking/latest/ of the OpenStack project in general and the adopt the special rules of the OpenStack SDk in specific where applicable unless otherwise stated.
The SDK project which the OTC Extensions augment developed a set of coding standards and guidelines were developed. Note that not all code of OTC Extensions adheres to these standards just yet. All new code has to adhere to these guidelines.
Below are the patterns and principles that we expect developers to follow.
Release Notes¶
OTC Extensions use reno for managing its release notes. A new release note should be added to your contribution anytime you add new API calls, fix significant bugs, add new functionality or parameters to existing API calls, or make any other significant changes to the code base that we should draw attention to for the user base.
It is not necessary to add release notes for minor fixes, such as correction of documentation typos, minor code cleanup or reorganization, or any other change that a user would not notice through normal usage.
Exceptions¶
Exceptions should never be wrapped and re-raised inside of a new exception. This removes important debug information from the user. All of the exceptions should be raised correctly the first time.
API Methods of openstack.cloud¶
The openstack.cloud layer has some specific rules:
When an API call acts on a resource that has both a unique ID and a name, that API call should accept either identifier with a name_or_id parameter.
All resources should adhere to the get/list/search interface that control retrieval of those resources. E.g., get_image(), list_images(), search_images().
Resources should have create_RESOURCE(), delete_RESOURCE(), update_RESOURCE() API methods (as it makes sense).
For those methods that should behave differently for omitted or None-valued parameters, use the _utils.valid_kwargs decorator. Notably: all Neutron update_* functions.
Deleting a resource should return True if the delete succeeded, or False if the resource was not found.
Returned Resources¶
Complex objects returned to the caller must be a munch.Munch type. The openstack._adapter.ShadeAdapter class makes resources into munch.Munch.
All objects should be normalized. It is shade’s purpose in life to make OpenStack consistent for end users, and this means not trusting the clouds to return consistent objects. There should be a normalize function in openstack/cloud/_normalize.py that is applied to objects before returning them to the user.
Fields should not be in the normalization contract if we cannot commit to providing them to all users.
Fields should be renamed in normalization to be consistent with the rest of openstack.cloud. For instance, nothing in openstack.cloud exposes the legacy OpenStack concept of “tenant” to a user, but instead uses “project” even if the cloud in question uses tenant.
Tests¶
New API methods must have unit tests.
New unit tests should only mock at the REST layer using requests_mock. Any mocking of openstacksdk itself should be considered legacy and to be avoided. Exceptions to this rule can be made when attempting to test the internals of a logical shim where the inputs and output of the method aren’t actually impacted by remote content.
Functional tests should be added, when possible.
In functional tests, always use unique names (for resources that have this attribute) and use it for clean up (see next point).
In functional tests, always define cleanup functions to delete data added by your test, should something go wrong. Data removal should be wrapped in a try except block and try to delete as many entries added by the test as possible.
Docstrings¶
Docstrings should only use triple-double-quotes (""").
Single-line docstrings should never have extraneous whitespace between enclosing triple-double-quotes.
Sentence fragments do not have punctuation. Specifically in the command classes the one line docstring is also the help string for that command and those do not have periods.
“””A one line docstring looks like this”””
Calling Methods¶
When breaking up method calls due to the 79 char line length limit, use the alternate four space indent. With the first argument on the succeeding line all arguments will then be vertically aligned. Use the same convention used with other data structure literals and terminate the method call with the last argument line ending with a comma and the closing paren on its own line indented to the starting line level.
Python 3 Compatibility¶
The OTC Extensions are developed for Python 3. Compatibility for Python 2.7 might be present, but would be so on accident.