feat: create and manage standalone Holoscan Modules

[wyli]

Summary

This adds a first-class workflow for creating and developing standalone Holoscan Modules with the global holoscan command. Module authors no longer need a HoloHub checkout or a repository-local holoscan/holohub launcher.

Module workflow

python -m pip install 'holoscan-cli[create]'
holoscan create "My Sensor"
cd holoscan-my-sensor

holoscan run-container
holoscan build my_sensor_pipeline
holoscan run my_sensor_pipeline
holoscan test

The generated repository includes operator and application examples, Module metadata, CMake and Python packaging support, tests, CI scaffolding, a development Dockerfile, and an exact requirements-cli.txt contract.

The CLI discovers the Module from its metadata when commands run from the repository root or a nested directory. It also supports explicitly selecting a Module from elsewhere:

holoscan --project-root /path/to/holoscan-my-sensor list

Creation can populate a missing destination, an empty directory, or a cloned repository containing only .git. Existing Git state is preserved, while non-empty destinations are rejected instead of overwritten.

Existing HoloHub wrapper behavior and custom Cookiecutter templates remain supported. Creation dependencies stay optional through the holoscan-cli[create] extra.

Validation

• 466 unit tests passed, 1 skipped
• Full pre-commit suite passed
• Wheel and source-distribution validation passed
• Clean-environment package installation and Module creation passed
• Generated development image build passed
• End-to-end Module build, run, test, install, and package lifecycle passed

AI-assisted: Created with Codex/GPT at the user's request.

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Dependency Review

The following issues were found:

• ✅ 0 vulnerable package(s)
• ✅ 0 package(s) with incompatible licenses
• ✅ 0 package(s) with invalid SPDX license definitions
• ⚠️ 1 package(s) with unknown licenses.

See the Details below.

License Issues

src/holoscan_cli/setup_scripts/requirements.template.txt

Package	Version	License	Issue Type
packaging	>= 23.0	Null	Unknown License

Allowed Licenses:

Apache-2.0, BSD-2-Clause, BSD-3-Clause, ISC, MIT, MPL-2.0, Python-2.0, Unlicense, 0BSD

OpenSSF Scorecard

Package	Version	Score	Details
pip/packaging	>= 23.0	Unknown	Unknown

Scanned Files

• src/holoscan_cli/setup_scripts/requirements.template.txt

[wyli]

Closing this prototype. It demonstrated the standalone-Module idea, and the review feedback here was folded into main via #221 — notably the shared resolve_module_name helper that aligned gather_metadata and package.py.

The work continues on a branch that supersedes this one: it carries these commits plus the [tool.holoscan] project configuration that lets a repository drop its ./holohub wrapper, and several fixes found while validating the full lifecycle end to end (SDK precedence, --version resilience, HOLOSCAN_CLI_ROOT validation, and generated-Module packaging). A replacement PR will follow.