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Subscribing functions to CloudEvents

You can subscribe a function to a set of events. This links your function to CloudEvent objects defined by your filters and enables automated responses.

Subscribing a function to CloudEvents

The subscribe command connects the function to a set of events, matching a series of filters for CloudEvent metadata and a Knative Broker as the source of events, from where they are consumed.

Prerequisites

  • You have installed Knative Eventing on the cluster.

  • You have configured a Knative Broker.

  • You have installed the Knative (kn) CLI.

Procedure

  1. Subscribe the function to events for a given broker by running the following command:

    Example command
    $ kn func subscribe --filter type=com.example.Hello --source my-broker

    Use the --source flag to specify the broker and one or more --filter flags to specify your filters.

    You can also omit the --source flag to use the default broker:

    Example command
    $ kn func subscribe --filter type=com.example --filter extension=my-extension-value

  2. Deploy the function with Knative Triggers:

    Example command
    $ kn func deploy
    Example output
    🙌 Function image built: <registry>/hello:latest
🎯 Creating Triggers on the cluster
✅ Function deployed in namespace "default" and exposed at URL:
http://hello.default.my-cluster.example.com