SMAP L2 Gridding Service

This repository contains the code for the SMAP-L2-Gridding-Service, which is a python service that transforms NASA level 2 gridded trajectory data into gridded NetCDF4-CF output files.

This code currently works on SPL2SMP_E data and will be adapted for other SMAP collections of gridded trajectory data.

Transforming Data

The logic of transforming data is contained in the smap_l2_gridder directory. It reads NASA L2 Gridded trajectory data and writes output NetCDF-CF files with the trajecotry style data correctly populated into EASE2 grids.

Commandline invocation

To run the regridder on an input file. Create an isolated python 3.12 environment using packages from the pip_requirements.txt file and then from the commandline run:

python -m smap_l2_gridder --input path/to/granule.h5 --output path/to/output_granule.nc

smap_l2_gridder/__main__.py is the entrypoint to the science logic module and can be used for testing and development.

Directory structure

📁
├── CHANGELOG.md
├── CONTRIBUTING.md
├── LICENSE
├── README.md
├── 📁 bin
├── 📁 docker
├── 📁 harmony_service
├── pip_requirements.txt
├── pyproject.toml
├── 📁 smap_l2_gridder
└── 📁 tests

• CHANGELOG.md - Contains a record of changes applied to each new release of the SMAP-L2-Gridding-Service.
• CONTRIBUTING.md - Instructions on how to contribute to the repository.
• LICENSE - Required for distribution under NASA open-source approval. Details conditions for use, reproduction and distribution.
• README.md - This file, containing guidance on developing the library and service.
• bin - A directory containing utility scripts to build the service and test images. A script to extract the release notes for the most recent version, as contained in CHANGELOG.md is also in this directory.
• docker - A directory containing the Dockerfiles for the service and test images. It also contains service_version.txt, which contains the semantic version number of the library and service image. Update this file with a new version to trigger a release.
• harmony_service - A directory containing the Harmony Service specific python code. adapter.py contains the SMAPL2GridderAdapter class that is invoked by calls to the Harmony service.
• pip_requirements.txt - Contains a list of python packages needed to run the service.
• pyproject.toml - Configuration file used by packaging tools, and other tools such as linters, type checkers, etc.
• smap_l2_gridder - Python package containing the logic for reformatting L2G data.
• tests - Contains the pytest test suite.

Local development

Local testing of service functionality can be achieved via a local instance of Harmony aka Harmony-In-A-Box. Please see instructions there regarding creation of a local Harmony instance.

For local development and testing of library modifications or small functions independent of the main Harmony application:

1. Create a Python virtual environment
2. Install the dependencies in pip_requirements.txt, and tests/pip_test_requirements.txt
3. Install the pre-commit hooks (described below).

Tests

This service utilises the Python pytest package to perform unit tests on classes and functions in the service. After local development is complete, and test have been updated, they can be run in Docker via:

$ ./bin/build-image
$ ./bin/build-test
$ ./bin/run-test

It is also possible to run the test scripts directly (without docker) by just running the run_tests.sh script with a proper python environment. Do note that the reports directory will appear in the directory you call the script from.

The tests/run_tests.sh script will also generate a coverage report, rendered in HTML, and scan the code with pylint.

Currently, the pytest suite is run automatically within a GitHub workflow as part of a CI/CD pipeline. These tests are run for all changes made in a PR against the main branch. The tests must pass in order to merge the PR.

pre-commit hooks

This repository uses pre-commit to enable pre-commit checks that enforce coding standard best practices. These include:

• Removing trailing whitespaces.
• Removing blank lines at the end of a file.
• Ensure JSON files have valid formats.
• ruff Python linting checks.
• black Python code formatting checks.

To enable these checks:

# Install pre-commit Python package:
pip install pre-commit

# Install the git hook scripts:
pre-commit install

Versioning

Docker service images for the smap_l2_gridder adhere to semantic version numbers: major.minor.patch.

• Major increments: These are non-backwards compatible API changes.
• Minor increments: These are backwards compatible API changes.
• Patch increments: These updates do not affect the API to the service.

CI/CD

The CI/CD for SMAP-L2-Gridding-Service is run on github actions with the workflows in the .github/workflows directory:

• run_lib_tests.yml - A reusable workflow that tests the library functions against the supported python versions.
• run_service_tests.yml - A reusable workflow that builds the service and test Docker images, then runs the Python unit test suite in an instance of the test Docker container.
• run_tests_on_pull_requests.yml - Triggered for all PRs against the main branch. It runs the workflow in run_service_tests.yml and run_lib_tests.yml to ensure all tests pass for the new code.
• publish_docker_image.yml - Triggered either manually or for commits to the main branch that contain changes to the docker/service_version.txt file.
• publish_release.yml - workflow runs automatically when there is a change to the docker/service_version.txt file on the main branch. This workflow will:
  • Run the full unit test suite, to prevent publication of broken code.
  • Extract the semantic version number from docker/service_version.txt.
  • Extract the released notes for the most recent version from CHANGELOG.md.
  • Build and deploy a this service's docker image to ghcr.io.
  • Publish a GitHub release under the semantic version number, with associated git tag.

Releasing

A release consists of a new Docker image for the harmony-SMAP-L2-gridding-service published to github's container repository.

A release is made automatically when a commit to the main branch contains a changes in the docker/service_version.txt file, see the publish_release workflow in the CI/CD section above.

Before merging a PR that will trigger a release, ensure these two files are updated:

• CHANGELOG.md - Notes should be added to capture the changes to the service and a link to the current pull request should be included.
• docker/service_version.txt - The semantic version number should be updated to trigger the release.

The CHANGELOG.md file requires a specific format for a new release, as it looks for the following string to define the newest release of the code (starting at the top of the file).

## [vX.Y.Z] - YYYY-MM-DD

Where the markdown reference needs to be updated at the bottom of the file following the existing pattern.

[vX.Y.Z]: https://github.com/nasa/harmony-SMAP-L2-gridding-service/releases/tag/X.Y.Z