user-defined-sinks.md

User-defined Sinks

A Pipeline may have multiple Sinks, those sinks could either be a pre-defined sink such as kafka, log, etc., or a user-defined sink.

A pre-defined sink vertex runs single-container pods, a user-defined sink runs two-container pods.

Build Your Own User-defined Sinks

You can build your own user-defined sinks in multiple languages.

Check the links below to see the examples for different languages.

• Golang
• Java
• Python

A user-defined sink vertex looks like below.

spec:
  vertices:
    - name: output
      sink:
        udsink:
          container:
            image: my-sink:latest

Available Environment Variables

Some environment variables are available in the user-defined sink container:

• NUMAFLOW_NAMESPACE - Namespace.
• NUMAFLOW_POD - Pod name.
• NUMAFLOW_REPLICA - Replica index.
• NUMAFLOW_PIPELINE_NAME - Name of the pipeline.
• NUMAFLOW_VERTEX_NAME - Name of the vertex.

User-defined Sinks contributed from the open source community

If you're looking for examples and usages contributed by the open source community, head over to the numaproj-contrib repositories.

These user-defined sinks like AWS SQS, GCP Pub/Sub, provide valuable insights and guidance on how to use and write a user-defined sink.