Extracting process environment variables

What's the recommended approach to extracting a specific set of environment variables from an event?

Failing to find a syntax to reference the fields within process.env, I did find that using a script/javascript processor the values can be extracted and assigned to fields.

This feels a bit sloppy, it would be nice to be able to apply the normal copy/move/rename operators. Perhaps also a filter for the sub-fields to extract in add_process_metadata.

Side note: the script processor is missing from the auditbeat docs.

Example config:

  - add_process_metadata:
      include_fields: [ "process.env"]
      restricted_fields: true
      ignore_missing: true
      fail_on_error: false
  - script:
      lang: javascript
      tag: extract_env_vars
      source: >
        function process(event) {
          var env;
          var v;
          if(env = event.Get("process.env")) {
            if(v = env['JOB_NAME]) event.Put("job_name", v);
            if(v = env['JOB_ID]) event.Put("job_id", v);
          }
        }