README.md

Quickwin - An Application Package with inline Python code

This repository contains a simple Python application app.py including a simple unit test as a demonstration of a "real" yet very simple Python EO application.

Using CWL's InitialWorkDirRequirement, a requirement that defines a list of files and subdirectories that must be staged by the workflow platform prior to executing the command line tool, the Python script app.py is staged and executed in a container.

For easing the development of the Python script app.py, its content is added to a template named workflow.cwl.template by this repository Github actions.

The CWL document generated is available in the releases section.

Generate the Application Package with the inline code

Update the Application Package template workflow.cwl.template with the Python app.py as the inline code to run:

content=`cat app.py` yq eval '.$graph[1].requirements.InitialWorkDirRequirement.listing[0].entry=strenv(content)' workflow.cwl.template > workflow.cwl

Here's a breakdown of the command:

• cat app.py: This command outputs the contents of the app.py file.

• yq eval '.$graph[1].requirements.InitialWorkDirRequirement.listing[0].entry=strenv(content)' workflow.cwl.template: This command uses yq to evaluate a YAML expression on the workflow.cwl.template file. The expression modifies the entry at a specific path in the CWL InitialWorkDirRequirement, setting it to the content of app.py.

• > workflow.cwl: This part of the command redirects the modified output to a new file named workflow.cwl.

Run the Application Package

The new workflow.cwl can be executed with:

cwltool workflow.cwl params.yaml

Where params.yaml contains:

item: "https://earth-search.aws.element84.com/v0/collections/sentinel-s2-l2a-cogs/items/S2B_10TFK_20210713_0_L2A"
aoi: "-121.399,39.834,-120.74,40.472"
epsg: "EPSG:4326"

Run the released Application Package

The release 1.0.0 contains the released Application Package include the update docker reference published in the Github container registry.

Run the released Application Package with:

cwltool \
    https://github.com/eoap/quickwin-inline-code/releases/download/1.0.0/app-water-body-inline-code.1.0.0.cwl \
    params.yaml 

Explanation

The Application Package defines a workflow for detecting water bodies based on Normalized Difference Water Index (NDWI) and Otsu threshold using Sentinel-2 data.

The key components of this CWL document are:

• Name: Water bodies detection based on NDWI and the Otsu threshold.

• Description: Workflow for detecting water bodies based on NDWI and Otsu threshold applied to a single Sentinel-2 Cloud-Optimized GeoTIFF (COG) SpatioTemporal Asset Catalog (STAC) item.

• Inputs:

  • aoi: Area of interest as a bounding box.
  • epsg: EPSG code (default: "EPSG:4326").
  • bands: Bands used for NDWI (default: ["green", "nir"]).
  • item: Reference to a STAC item.

• Outputs:

  • stac_catalog: Output directory containing the STAC catalog.

• Steps:

  • node_detect: Executes the detect-water-body tool with specified inputs and produces a STAC catalog in the output directory.

• Tool: detect-water-body:

  • A CommandLineTool written in Python that uses various libraries such as rasterio, skimage, pyproj, shapely and loguru.
  • It performs operations like cropping, thresholding, and creating a STAC catalog for the detected water bodies.
  • It takes inputs like STAC item URL, area of interest, EPSG code, and band names.

• Tool Requirements:

  • Uses Docker.
  • Specifies resource requirements (coresMax: 1, ramMax: 512).
  • Sets up initial working directory with an entry script (app.py).

• Execution:

  • The workflow runs the detect-water-body tool with specified inputs.
  • Generates a STAC catalog with the detected water bodies.
  • Cleans up temporary files after completion.

The webpage of the documentation is https://eoap.github.io/quickwin-inline-code/.