Chapter 26. Downgrading Streams for Apache Kafka

Procedure

1. Take note of any configuration changes made to the existing Cluster Operator resources (in the /install/cluster-operator directory). Any changes will be overwritten by the previous version of the Cluster Operator.
2. Revert your custom resources to reflect the supported configuration options available for the version of Streams for Apache Kafka you are downgrading to.

3. Update the Cluster Operator.

   1. Modify the installation files for the previous version according to the namespace the Cluster Operator is running in.

      On Linux, use:

      sed -i 's/namespace: .*/namespace: my-cluster-operator-namespace/' install/cluster-operator/*RoleBinding*.yaml

      On MacOS, use:

      sed -i '' 's/namespace: .*/namespace: my-cluster-operator-namespace/' install/cluster-operator/*RoleBinding*.yaml

   2. If you modified one or more environment variables in your existing Cluster Operator Deployment, edit the install/cluster-operator/060-Deployment-strimzi-cluster-operator.yaml file to use those environment variables.

4. When you have an updated configuration, deploy it along with the rest of the installation resources:

   oc replace -f install/cluster-operator

   Wait for the rolling updates to complete.

5. Get the image for the Kafka pod to ensure the downgrade was successful:

   oc get pod my-cluster-kafka-0 -o jsonpath='{.spec.containers[0].image}'

   The image tag shows the new Streams for Apache Kafka version followed by the Kafka version. For example, <strimzi_version>-kafka-<kafka_version>.

   You can also check the downgrade has completed successfully from the status of the Kafka resource.

Procedure

1. Update the Kafka cluster configuration.

   oc edit kafka <kafka_configuration_file>

2. Change the metadataVersion version to a version supported by the Kafka version you are downgrading to; leave the Kafka.spec.kafka.version unchanged at the current Kafka version.

   For example, if downgrading from Kafka 3.7.0 to 3.6.0:

   apiVersion: kafka.strimzi.io/v1beta2
   kind: Kafka
   metadata:
     name: my-cluster
   spec:
     kafka:
       replicas: 3
       metadataVersion: 3.6-IV2 1
       version: 3.7.0 2
       # ...

   1

   Metadata version is changed to a version supported by the earlier Kafka version.

   2

   Kafka version is unchanged.

   Note

   The value of metadataVersion must be a string to prevent it from being interpreted as a floating point number.

3. Save the change, and wait for Cluster Operator to update .status.kafkaMetadataVersion for the Kafka resource.

4. Change the Kafka.spec.kafka.version to the previous version.

   For example, if downgrading from Kafka 3.7.0 to 3.6.0:

   apiVersion: kafka.strimzi.io/v1beta2
   kind: Kafka
   metadata:
     name: my-cluster
   spec:
     kafka:
       replicas: 3
       metadataVersion: 3.6-IV2 1
       version: 3.6.0 2
       # ...

   1

   Metadata version is supported by the Kafka version.

   2

   Kafka version is changed to the new version.

5. If the image for the Kafka version is different from the image defined in STRIMZI_KAFKA_IMAGES for the Cluster Operator, update Kafka.spec.kafka.image.

   See Section 25.2.3, “Kafka version and image mappings”.

6. Wait for the Cluster Operator to update the cluster.

   You can check the downgrade has completed successfully from the status of the Kafka resource.

7. Downgrade all client applications (consumers) to use the previous version of the client binaries.

   The Kafka cluster and clients are now using the previous Kafka version.