Message queues
If you use cron jobs—or some other external process manager—to manage message queues instead of RabbitMQ, you may need to use an environment variable to restart message queue consumers after every deployment. (Requires Magento Commerce Cloud version 2.2.0 or later.)
Symptom
Message queue consumers fail to restart after you deploy code to an environment.
Solution
Use the CRON_CONSUMERS_RUNNER
environment variable to ensure that consumers are retrieving messages from the message queue.