Property Files and JsonGet

Use property files to store information from the output of a processing step. This is particularly useful when analyzing the results of a processing step to decide how a conditional step should be executed. The JsonGet function processes a property file and enables you to use JsonPath notation to query the property JSON file. For more information on JsonPath notation, see the JsonPath repo.

To store a property file for later use, you must first create a PropertyFile instance with the following format. The path parameter is the name of the JSON file to which the property file is saved. Any output_name must match the output_name of the ProcessingOutput that you define in your processing step. This enables the property file to capture the ProcessingOutput in the step.

from sagemaker.workflow.properties import PropertyFile

<property_file_instance> = PropertyFile(
    name="<property_file_name>",
    output_name="<processingoutput_output_name>",
    path="<path_to_json_file>"
)

When you create your ProcessingStep instance, add the property_files parameter to list all of the parameter files that the Amazon SageMaker Model Building Pipelines service must index. This saves the property file for later use.

property_files=[<property_file_instance>]

To use your property file in a condition step, add the property_file to the condition that you pass to your condition step as shown in the following example to query the JSON file for your desired property using the json_path parameter.

cond_lte = ConditionLessThanOrEqualTo(
    left=JsonGet(
        step_name=step_eval.name,
        property_file=<property_file_instance>,
        json_path="mse"
    ),
    right=6.0
)

For more in-depth examples, see Property File in the Amazon SageMaker Python SDK.