feat(pubsub/pulsar): register CloudEvents envelope Avro schema with Pulsar Schema Registry

[javier-aliaga]

Description

When Dapr publishes to Pulsar with CloudEvents wrapping enabled (the default), the wire format is a CloudEvents envelope containing the user's domain event in the data field. Previously, the Avro schema registered with the Pulsar Schema Registry was the inner domain event schema, not the CloudEvents envelope — causing a mismatch between the schema in the registry and the actual messages stored in the topic.

This PR fixes the mismatch by wrapping the user-provided Avro schema inside a CloudEvents envelope Avro schema before registering it with the broker.

Note: explicit error for rawPayload on Avro schema topics

Pulsar enforces a single schema per topic. Previously, publishing with rawPayload=true to an Avro-schema topic would fail silently or produce confusing errors due to the schema/wire mismatch. This was never a working combination.

This PR makes the constraint explicit. The component now returns a clear error:

rawPayload=true is not compatible with Avro schema topics using CloudEvents envelope; use a separate topic for raw payloads

If you need raw payloads with Avro schema validation, use a dedicated topic that is only ever published to with rawPayload=true.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #[issue number]

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation
  • Created the dapr/docs PR:

Note: We expect contributors to open a corresponding documentation PR in the dapr/docs repository. As the implementer, you are the best person to document your work! Implementation PRs will not be merged until the documentation PR is opened and ready for review.

[Copilot]

Pull request overview

The PR implements registration of CloudEvents envelope Avro schemas with Pulsar Schema Registry. Previously, when Dapr published to Pulsar with CloudEvents wrapping enabled (the default), the schema registered with Pulsar was only the inner domain event schema, creating a mismatch with the actual wire format. This fix wraps the inner schema in a CloudEvents envelope Avro schema before registration.

Changes:

• New CloudEvents schema wrapping functionality in cloudevents_schema.go that embeds inner Avro schemas as the data field of a CloudEvents envelope
• Enhanced schemaMetadata structure to store both the inner schema codec and CloudEvents envelope codec
• Updated producer and consumer registration to use the CloudEvents envelope schema when available
• Added explicit error handling to reject rawPayload=true on Avro schema topics using CloudEvents envelopes
• Comprehensive test coverage for the new functionality

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pubsub/pulsar/cloudevents_schema.go	New file implementing CloudEvents Avro schema wrapping logic
pubsub/pulsar/cloudevents_schema_test.go	New comprehensive test file for schema wrapping with edge cases
pubsub/pulsar/metadata.go	Enhanced schemaMetadata struct with CE envelope fields
pubsub/pulsar/pulsar.go	Updated schema initialization, producer/consumer registration, and publish validation
pubsub/pulsar/pulsar_test.go	Added test helpers and new test cases for CE envelope handling

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