xym

xym extracts YANG modules from IETF RFCs and drafts. The source can be a local text/RFCXML file or a URL, and extracted modules are written as .yang files.

Install

Install the latest published package from PyPI:

python -m pip install xym

Install from a local checkout:

git clone https://github.com/xym-tool/xym.git
cd xym
python -m pip install .

After installation, verify the command is available:

xym --version
xym --help

Usage

Extract all YANG modules from a local source file into the current directory:

xym path/to/rfc-or-draft.txt

Write output to a specific directory:

xym --dstdir ./yang path/to/rfc-or-draft.txt

Extract from a URL:

xym https://www.rfc-editor.org/rfc/rfc7223.txt

Use strict extraction, requiring <CODE BEGINS> and <CODE ENDS> markers:

xym --strict True path/to/rfc-or-draft.txt

Only extract valid example modules in strict mode:

xym --strict True --strict-examples path/to/rfc-or-draft.txt

Parse only selected modules:

xym --parse-only-modules ietf-interfaces example-module path/to/rfc-or-draft.txt

Skip selected modules:

xym --skip-modules example-module path/to/rfc-or-draft.txt

Check or add revisions in output filenames using pyang:

xym --force-revision-pyang path/to/rfc-or-draft.txt

Check or add revisions in output filenames using regular expressions:

xym --force-revision-regexp path/to/rfc-or-draft.txt

Parse an RFCXMLv3 source file:

xym --rfcxml path/to/rfc-or-draft.xml

Extract code snippets as well as YANG modules:

xym --extract-code-snippets --code-snippets-dir ./snippets path/to/rfc-or-draft.txt

Add source line references to extracted YANG modules:

xym --add-line-refs path/to/rfc-or-draft.txt

Strict Mode

The --strict and --strict-examples options affect which modules are written:

• No strict options: all YANG modules found in the source are extracted.
• --strict True: only YANG modules inside <CODE BEGINS> and <CODE ENDS> are extracted.
• --strict True --strict-examples: only example modules outside <CODE BEGINS> and <CODE ENDS> with names starting with example- are extracted.

The tool prints warnings and errors for source issues that may need inspection. For example, it reports invalid example module placement, missing revisions, and module names that do not match output filenames.

If an output .yang file already exists, xym does not overwrite it.

Development

This project uses Hatch for packaging, test environments, wheel building, and version generation. Project metadata lives in pyproject.toml.

Install Hatch:

python -m pip install hatch

Show the version derived from Git tags:

hatch version

Run the test suite:

hatch run test:run

The tests include URL-based cases that fetch RFC text from the network. If those tests fail with DNS or connection errors, rerun them with network access.

Run the installed console command inside Hatch's test environment:

hatch run test:xym --version

Build source and wheel distributions:

hatch build

Build only the wheel:

hatch build -t wheel

Build artifacts are written to dist/.

Versioning

Versions are derived from Git tags with hatch-vcs. Release tags must use one of these formats:

v0.10.0
v0.10.0rc1

The v prefix is stripped from the package version. During build/install, Hatch generates xym/_version.py; that file is ignored by Git and should not be edited or committed.

Continuous Integration

GitHub Actions are defined in .github/workflows/workflow.yaml.

Pull requests automatically run:

hatch run test:run

The workflow currently tests Python 3.10, 3.11, 3.12, and 3.13.

Publishing

Publishing uses PyPI trusted publishing with GitHub Actions OIDC. No PyPI API token secret is required.

Configure a trusted publisher for the PyPI project xym with:

• Repository owner: xym-tool
• Repository name: xym
• Workflow name: workflow.yaml
• Environment name: leave blank unless the workflow is later changed to use one

To publish a release wheel:

git tag v0.10.0
git push origin v0.10.0

To publish a release candidate wheel:

git tag v0.10.0rc1
git push origin v0.10.0rc1

The publish job runs only for pushed tags matching:

^v[0-9]+\.[0-9]+\.[0-9]+(rc[0-9]+)?$

The publish job depends on the test job. If tests fail, the wheel is not published.