netsnmp-cffi

This is a CFFI-based Python interface for the Net-SNMP C library, enabling efficient parallel SNMP communication with large amounts of devices from Python. It provides both asynchronous (asyncio) and synchronous interfaces.

This module is still a work in progress, and has been mainly developed to replace PySNMP as the default SNMP library in Zino 2 - the first releases of this library will focus mainly on functionality used by Zino (which for the most part means that SNMPv3 is not implemented yet).

Compatibility

The library is intended to be compatible with Net-SNMP versions from 5.9 and newer, and with Python 3.9 and newer.

Usage examples

For a simple (asyncio) usage example, see asnmpget.py.

Developing netsnmp-cffi

Running tests

tox and pytest are used to run the test suite. To run the test suite on all supported versions of Python, run:

tox

Code style

netsnmp-cffi code should follow the PEP-8 and PEP-257 guidelines. Ruff is used for automatic code formatting. The pre-commit tool is used to enforce code styles at commit-time.

Before you start hacking, enable pre-commit hooks in your cloned repository, like so:

pre-commit install

Using towncrier to automatically produce the changelog

Before merging a pull request

To be able to automatically produce the changelog for a release one file for each pull request (also called news fragment) needs to be added to the folder changelog.d/.

The name of the file consists of three parts separated by a period:

1. The identifier: the issue number or the pull request number. If we don't want to add a link to the resulting changelog entry then a + followed by a unique short description.
2. The type of the change: we use security, removed, deprecated, added, changed and fixed.
3. The file suffix, e.g. .md, towncrier does not care which suffix a fragment has.

So an example for a file name related to an issue/pull request would be 214.added.md or for a file without corresponding issue +fixed-pagination-bug.fixed.md.

This file can either be created manually with a file name as specified above and the changelog text as content or one can use towncrier to create such a file as following:

$ towncrier create -c "Changelog content" 214.added.md

When opening a pull request there will be a check to make sure that a news fragment is added and it will fail if it is missing.

Before a release

To add all content from the changelog.d/ folder to the changelog file simply run

$ towncrier build --version {version}

This will also delete all files in changelog.d/.

To preview what the addition to the changelog file would look like add the flag --draft. This will not delete any files or change CHANGELOG.md. It will only output the preview in the terminal.

A few other helpful flags:

• date DATE - set the date of the release, default is today
• keep - do not delete the files in changelog.d/

More information about towncrier.

Building binary wheels

This package utilizes the API mode of CFFI, which means that it builds a small C shim to interface between the Net-SNMP library and Python. This means that a small platform-dependent binary will be part of the wheels built from this package.

In order to build wheels that should be compatible with at least several Linux distros and Python version combinations, and that are also uploadable to PyPI when making release, we utilize the manylinux tool suite.

Building the binary wheels should more or less be automated by a make command (see the Makefile itself for details):

make