Migrating from v4.3 to v4.4

Migrating from v4.3 to v4.4

API changes

ConfigurationService

We have simplified how to deal with the Kubernetes client. Previous versions provided direct access to underlying aspects of the client’s configuration or serialization mechanism. However, the link between these aspects wasn’t as explicit as it should have been. Moreover, the Fabric8 client framework has also revised their serialization architecture in the 6.7 version (see this fabric8 pull request for a discussion of that change), moving from statically configured serialization to a per-client configuration (though it’s still possible to share serialization mechanism between client instances). As a consequence, we made the following changes to the ConfigurationService API:

• Replaced getClientConfiguration and getObjectMapper methods by a new getKubernetesClient method: instead of providing the configuration and mapper, you now provide a client instance configured according to your needs and the SDK will extract the needed information from it

If you had previously configured a custom configuration or ObjectMapper, it is now recommended that you do so when creating your client instance, as follows, usually using ConfigurationServiceOverrider.withKubernetesClient:

class Example {

  public static void main(String[] args) {
    Config config; // your configuration
    ObjectMapper mapper; // your mapper
    final var operator = new Operator(overrider -> overrider.withKubernetesClient(
            new KubernetesClientBuilder()
                    .withConfig(config)
                    .withKubernetesSerialization(new KubernetesSerialization(mapper, true))
                    .build()
        ));
  }
}

Consequently, it is now recommended to get the client instance from the ConfigurationService.

Operator

It is now recommended to configure your Operator instance by using a ConfigurationServiceOverrider when creating it. This allows you to change the default configuration values as needed. In particular, instead of passing a Kubernetes client instance explicitly to the Operator constructor, it is now recommended to provide that value using ConfigurationServiceOverrider.withKubernetesClient as shown above.

Using Server-Side Apply in Dependent Resources

From this version by default Dependent Resources use Server Side Apply (SSA) to create and update Kubernetes resources. A new default matching algorithm is provided for KubernetesDependentResource that is based on managedFields of SSA. For details see SSABasedGenericKubernetesResourceMatcher

Since those features are hard to completely test, we provided feature flags to revert to the legacy behavior if needed, see in ConfigurationService

Note that it is possible to override the related methods/behavior on class level when extending the KubernetesDependentResource.

The SSA based create/update can be combined with the legacy matcher, simply override the match method and use the GenericKubernetesResourceMatcher directly. See related sample.

Migration from plain Update/Create to SSA Based Patch

Migration to SSA might not be trivial based on the uses cases and the type of managed resources. In general this is not a solved problem is Kubernetes. The Java Operator SDK Team tries to follow the related issues, but in terms of implementation this is not something that the framework explicitly supports. Thus, no code is added that tries to mitigate related issues. Users should thoroughly test the migration, and even consider not to migrate in some cases (see feature flags above).

See some related issues in kubernetes or here. Please create related issue in JOSDK if any.