def new_context(context_name, cluster_ca, config, username):
    """Build a new context and return cluster and context dictionaries."""
    cluster_address = config['contexts'][context_name]['cluster_address']
    cluster_dict = {'cluster': {'api-version': 'v1',
                    'certificate-authority-data': cluster_ca, 'server':
                    cluster_address}, 'name': context_name}
    context_dict = {'context': {'cluster': context_name, 'user': username},
                    'name': context_name}

    return {'context': context_dict, 'context_cluster': cluster_dict}