Kafka Schema Registry

Since Proton 1.5.2, Kafka schema registry is supported.

Read Messages in Protobuf or Avro Schema

To read Kafka data in Protobuf or Avro schema with a schema registry, you can create an external stream with kafka_schema_registry_url settings, e.g.

CREATE EXTERNAL STREAM my_stream (
  -- columns goes here ...
) SETTINGS
    type = 'kafka',
    brokers = '...',
    topic = '...',
    data_format = '..',
    kafka_schema_registry_url = 'http://url.to/my/schema/registry',
    kafka_schema_registry_credentials = 'API_KEY:API_SECRET',
    kafka_schema_registry_skip_cert_check = true|false,
    kafka_schema_registry_private_key_file = '..',
    kafka_schema_registry_cert_file = '..',
    kafka_schema_registry_ca_location = '..';

Please note:

1. kafka_schema_registry_credentials is optional. Skip this if the schema registry server doesn't require authentication.

2. Make sure to add http:// or https:// in the kafka_schema_registry_url. In Proton 1.5.3 or above, self-signed HTTPS certification is supported.

   1. One solution is to set kafka_schema_registry_skip_cert_check to true. This will completely skip the TLS certification verification. In this case, you don't need to specify the certification files.
   2. A more secure solution is to keep the default value of kafka_schema_registry_skip_cert_check, which is false. Omit this setting and specify the following 3 settings:
      1. kafka_schema_registry_private_key_file: the file path to the private key file used for encryption. Please use absolute file path and make sure Proton can access this file. If you are using Kubernetes or Docker, please mount the file systems properly.
      2. kafka_schema_registry_cert_file: the file path to the certificate file (in PEM format). If the private key and the certificate are stored in the same file, this can be empty if kakfa_schema_registry_private_key_file is specified.
      3. kafka_schema_registry_ca_location: the path to the file or directory containing the CA/root certificates.

3. Make sure you define the columns matching the fields in the Avro schema. You don't have to define all top level fields in Avro schema as columns in the stream. For example, if there are 4 fields in Avro schema, you can choose only 2 of them as columns in the external stream. But make sure the data types match.

4. data_format can be Avro, or ProtobufSingle.

5. Schema reference is not supported yet.

info

For examples to read Avro message in various Kafka API compatitable message platforms, please check this doc.

Write Messages

Writing Avro/Protobuf data with schema registry is not supported yet (coming soon).