How to add a header key:value pair when publishing a message with pika

I am writing an automated test to test a consumer. So far I did not need to include a header when publishing messages but now I do. And it seems like its lacking documentation.

This is my publisher:

class RMQProducer(object):

    def __init__(self, host, exchange, routing_key):
        self.host = host
        self.exchange = exchange
        self.routing_key = routing_key

    def publish_message(self, message):
        connection = pika.BlockingConnection(pika.ConnectionParameters(self.host))
        channel = connection.channel()
        message = json.dumps(message)
        channel.basic_publish(exchange=self.exchange,
                              routing_key=self.routing_key,
                              body=message)

I want to do smtn like:

channel.basic_publish(exchange=self.exchange,
                      routing_key=self.routing_key,
                      body=message,
                      headers={"key": "value"})

Whats the correct way to add headers to this message?

Solution

You would use pika.BasicProperties to add headers.

channel.basic_publish(exchange=self.exchange,
                      routing_key=self.routing_key,
                      properties=pika.BasicProperties(
                          headers={'key': 'value'} # Add a key/value header
                      ),
                      body=message)

The official documentation for pika does indeed not cover this scenario exactly, but the documentation does have the specifications listed. I would would strongly recommend that you bookmark this page, if you are going to continue using pika.