How to get the passed parameter inside python container in AWS Batch job?

I have 2 job definitions (job-1, job-2) and I'm executing Job1 first. Then Job1 will submit Job2 and starts its execution. I need to pass some parameters to Job2 when submitting the job. Below is my Python3 code,

# job1

import boto3
import os
env = os.environ.get('environment')

batch = boto3.client('batch')
def submit_job():
    return batch.submit_job(
        jobName='Job2',
        jobQueue='job2-queue-dev',
        jobDefinition='job-2',
        containerOverrides= {
           'environment': [
                {
                    'name': 'environment',
                    'value': env
                },
            ]
        },
        parameters={
          'opco': '123',
          'app' : 'app1'
        },
     );

submit_job()

In the Job2 i can easily get the environment variable with below code.

# job2
env = os.environ.get('environment')
def get_index_name(env):
    return 'liberty-'+env
....

So my question is How can we get those parameters (opco, app) inside the job2? FYI, i could pass them as environment variable, But i want to know how parameter retrieval is done here. Thanks in advance