Chapter 24. KafkaAuthorizationCustom schema reference

(Required) Java class that implements the org.apache.kafka.server.authorizer.Authorizer interface to support custom ACLs.

A list of user principals treated as super users, so that they are always allowed without querying ACL rules.

You can add configuration for initializing the custom authorizer using Kafka.spec.kafka.config.

apiVersion: kafka.strimzi.io/v1beta2
kind: Kafka
metadata:
  name: my-cluster
  namespace: myproject
spec:
  kafka:
    # ...
    authorization:
      type: custom
      authorizerClass: io.mycompany.CustomAuthorizer
      superUsers:
        - CN=client_1
        - user_2
        - CN=client_3
    # ...
    config:
      authorization.custom.property1=value1
      authorization.custom.property2=value2
    # ...

apiVersion: kafka.strimzi.io/v1beta2
kind: Kafka
metadata:
  name: my-cluster
  namespace: myproject
spec:
  kafka:
    # ...
    authorization:
      type: custom
      authorizerClass: io.mycompany.CustomAuthorizer
      superUsers:
        - CN=client_1
        - user_2
        - CN=client_3
    # ...
    config:
      authorization.custom.property1=value1
      authorization.custom.property2=value2
    # ...

In addition to the Kafka custom resource configuration, the JAR file containing the custom authorizer class along with its dependencies must be available on the classpath of the Kafka broker.

The AMQ Streams Maven build process provides a mechanism to add custom third-party libraries to the generated Kafka broker container image by adding them as dependencies in the pom.xml file under the docker-images/kafka/kafka-thirdparty-libs directory. The directory contains different folders for different Kafka versions. Choose the appropriate folder. Before modifying the pom.xml file, the third-party library must be available in a Maven repository, and that Maven repository must be accessible to the AMQ Streams build process.

Custom authorization can make use of group membership information extracted from the JWT token during authentication when using oauth authentication and configuring groupsClaim configuration attribute. Groups are available on the OAuthKafkaPrincipal object during authorize() call as follows:

    public List<AuthorizationResult> authorize(AuthorizableRequestContext requestContext, List<Action> actions) {

        KafkaPrincipal principal = requestContext.principal();
        if (principal instanceof OAuthKafkaPrincipal) {
            OAuthKafkaPrincipal p = (OAuthKafkaPrincipal) principal;

            for (String group: p.getGroups()) {
                System.out.println("Group: " + group);
            }
        }
    }

    public List<AuthorizationResult> authorize(AuthorizableRequestContext requestContext, List<Action> actions) {

        KafkaPrincipal principal = requestContext.principal();
        if (principal instanceof OAuthKafkaPrincipal) {
            OAuthKafkaPrincipal p = (OAuthKafkaPrincipal) principal;

            for (String group: p.getGroups()) {
                System.out.println("Group: " + group);
            }
        }
    }

The type property is a discriminator that distinguishes use of the KafkaAuthorizationCustom type from KafkaAuthorizationSimple, KafkaAuthorizationOpa, KafkaAuthorizationKeycloak. It must have the value custom for the type KafkaAuthorizationCustom.