### [Read this on the main serverless docs site](https://www.serverless.com/framework/docs/providers/kubeless/events/pubsub) # Kubeless PubSub Events Kubeless functions can also be registered to listen to PubSub events in a Kafka topic. Kafka (and Zookeeper) are deployed in your Kubernetes cluster as part of the Kubeless deployment. The function then will be triggered whenever a message is published under a certain topic. The topic in which the function will be listening is defined in the events section of the `serverless.yml`: ``` service: hello provider: name: kubeless runtime: python2.7 plugins: - serverless-kubeless functions: hello: handler: handler.hello events: - trigger: 'hello_topic' ``` ## Triggering a function You can trigger a function by publishing a message under a certain topic. The Kubeless CLI allows to do this from your command line: ``` kubeless topic publish --topic hello_topic --data 'hello world!' # push a message into the queue serverless logs -f hello # Output hello world! ``` You can install the Kubeless CLI tool following the [installation guide](../guide/installation.md).