This assumes you have created a RabbitMQ user with the administrator tag.

Refer to the RabbitMQ REST API documentation.

The curl command with the --user option can be used to make an API connection to RabbitMQ. In this example, John Doe will make a connection to the RabbitMQ server listening on port 15671 and then create a policy named deadletter.policy.

curl
--request PUT
--user john.doe:itsasecret
--url http://hostname:15671/api/policies/vhost001/deadletter.policy
--header 'content-type: application/json'
--data '{ "pattern": "foo.queue", "apply-to": "queues", "priority": 0, "definition": {"dead-letter-exchange": "deadletter.exchange", "max-length-bytes": 1048576, "overflow": "reject-publish-dlx" } }'
--write-out "%{http_code}"

For the / vhost, use %2F

curl
--request PUT
--user john.doe:itsasecret
--url http://hostname:15671/api/policies/%2f/deadletter.policy
--header 'content-type: application/json'
--data '{ "pattern": "foo.queue", "apply-to": "queues", "priority": 0, "definition": {"dead-letter-exchange": "deadletter.exchange", "max-length-bytes": 1048576, "overflow": "reject-publish-dlx" } }'
--write-out "%{http_code}"

No output will be returned, regardless if the policy is or is not created. For this reason, the -w or --write-out option is included to get the return code of the curl command.