SBN Survey Image Service AWS

What's This?

This is a lambda function with S3-caching to retrieve FITS and JPEG images. The function is intended to be served by AWS's Gateway API. URLs requesting data take the following format:

https://HOST/api/images/urn:nasa:pds:gbo.ast.catalina.survey:data_calibrated:703_20220122_2b_n32022_01_0003.arch?ra=107.10813&dec=30.84928&size=5arcmin&format=jpeg

It is used by CATCH and other services maintained by SBN at UMD.

Overview

The AWS Lambda function:

1. Receives path and query parameters.
2. Formulate a unique file name based on the query.
3. Checks if a corresponding file exists within a data cache backed by an S3 bucket.
4. If the file exists, it is returned to the user.
5. If the file does not exist, then the data is retrieved from externally hosted services.
6. Images are converted to the user's requested format (e.g., JPEG or PNG).
7. The result is cached to S3 and returned to the user.

Catalina Sky Survey, NEAT, and Spacewatch data archived at sbnarchive.psi.edu are presently supported.

Development notes

Testing

Unit tests are in the src/test_sbn_sis.py file. They are designed to be run with pytest src/. The tests can also be run with the Makefile, which will setup a virtual environment in the test-venv directory:

make test

Misc

Test Lambda function:

{
  "queryStringParameters": {
    "lid": "urn:nasa:pds:gbo.ast.catalina.survey:data_calibrated:g96_20210402_2b_f5q9m2_01_0001.arch",
    "ra": 190.99166667,
    "dec": 23.92305556,
    "size": "5 arcmin",
    "format": "jpeg"
  }
}

Test API Gateway query string:

/images/urn:nasa:pds:gbo.ast.catalina.survey:data_calibrated:g96_20210402_2b_f5q9m2_01_0001.arch?ra=190.99166667&dec=23.92305556&size=5arcmin&format=jpeg

Test API Gateway method:

lid: urn:nasa:pds:gbo.ast.catalina.survey:data_calibrated:g96_20210402_2b_f5q9m2_01_0001.arch Query strings: ra=190.99166667&dec=23.92305556&size=5arcmin