Add option to JsonSerializer to use Spring primary ObjectMapper bean

[yoransabern]

Can we get an option to have the producer value-serializer use the ObjectMapper bean instantiated by Spring boot instead of having to configure a custom JsonSerializer and ProducerFactory bean?

This is usefull to do all kafka configuration through the properties instead of having to do custom code configuration, and I think most spring libraries already get the primary ObjectMapper bean if it is available.

[yoransabern]

Same goes for the JsonDeserializer.

[yoransabern]

Some explanation behind this requirement:

To properly serialize and deserialize the Java.time.Instant objects, the objectmapper requires a java time module to be set.

It would also be usefull to specify modules to be set for the Object mappers used in the serializers.

[garyrussell]

That can't be done by this project, it would need to be done, somehow, in Boot's auto configuration.

When providing the (De)Serializer class through Kafka properties, the Kafka client instantiates the object, not Spring. Kafka knows nothing about Spring or Boot.

The only way for Spring to do the instantiation is through a custom Producer/Consumer factory, taking the (De)Serializers as constructor arguments.

So, I suggest moving this request to spring-boot; perhaps some new properties could trigger conditional injection of key/value (de)serializers.

[yoransabern]

Ah alright, I guess it would not be an option to set the Java Time module on the objectmapper which is created in the serializer based on a spring.kafka property?

[artembilan]

I guess it would not be an option to set the Java Time module on the objectmapper which is created in the serializer based on a spring.kafka property?

Well, I don't think so.
We really can do in the JsonSerializer ctor - something similar what we have in Spring Integration with its Jackson2JsonObjectMapper: https://github.com/spring-projects/spring-integration/blob/master/spring-integration-core/src/main/java/org/springframework/integration/support/json/Jackson2JsonObjectMapper.java#L154

[mle-enso]

Is there any news on this one?

[artembilan]

I think the solution I provide in the #1053 is a good compromise where we don't have anything auto-configured, but really would like to rely on the classpath.
The story about auto-configuration JSON (de)serializers in Spring Boot is fully different issue and belongs that project.

Thanks

[jbotuck]

When providing the (De)Serializer class through Kafka properties, the Kafka client instantiates the object, not Spring. Kafka knows nothing about Spring or Boot.

The only way for Spring to do the instantiation is through a custom Producer/Consumer factory, taking the (De)Serializers as constructor arguments.

Why can't we have the constructor of the(De)Serializer class look for an ObjectMapper bean in the application context before constructing its own ObjectMapper?