It seems to be related to trains-apiserver , based on the log inside the Docker compose:

trains-apiserver | [2020-11-10 04:40:14,133] [8] [ERROR] [trains.service_repo] Returned 500 for queues.get_next_task in 20ms, msg=General data error: err=('1 document(s) failed to index.', [{'index': {'_index': 'queue_metrics_d1bd92a3b039400cbafc60a7a5b1e52b_2020-11', '_type': '_doc', '_id': 'rkh0sHUBwyiZSyeZUAov', 'status': 403, 'error': {'type': 'cluster_block_exception', 'reason': 'index [queue_metrics_d1bd92a3b039400cbafc60a7a5b1e52b_2020-11] blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];'}, 'data': {'timestamp': 1604983214115, 'queue': '789a8744857746de84db036d65de8c65', 'average_waiting_time': 0, 'queue_length': 0}}}]), extra_info=index [queue_metrics_d1bd92a3b039400cbafc60a7a5b1e52b_2020-11] blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];