Begin by configuring a Jenkins job that collects the data you need. This can be done by writing a script that runs within Jenkins to extract the required information. Ensure the data is outputted in a structured format (e.g., CSV or plain text) that can be easily manipulated in subsequent steps.

Use Jenkins' built-in capabilities by installing any necessary plugins that aid in processing the output data. For instance, the Groovy Postbuild plugin can be useful for executing Groovy scripts that process data, but ensure no third-party data connectors are involved.

Develop a Groovy script that runs as part of your Jenkins job to transform the gathered data into a JSON format. Groovy has built-in JSON support, allowing you to parse and generate JSON data structures. Write the script to read the extracted data, manipulate it as needed, and convert it into JSON.

Integrate the Groovy script into the Jenkins job configuration. This can be done by adding a "Execute System Groovy Script" build step that runs your script. Ensure that the script has access to the workspace where the initial data is stored so it can read and process the data correctly.

Modify your Groovy script to write the JSON output to a file within the Jenkins workspace. Use standard file I/O operations available in Groovy to create and write the JSON data to a file. Choose a meaningful file name and location within the workspace for easy access and retrieval.

Leverage Jenkins' built-in archiving capabilities to save the JSON file as part of the build artifacts. Add a "Post-build Actions" step to archive the file. This makes it accessible from the Jenkins build results for downloading or further processing.

Finally, automate the Jenkins job by scheduling it to run at desired intervals using the "Build Triggers" section. Set up a cron schedule if needed, ensuring the data is regularly updated and transferred to the JSON file. This ensures the process can run without manual intervention, keeping your data up-to-date.