// This module is included in the following assemblies:
//
// assembly-upgrading-kafka-versions.adoc

[id='con-versions-and-images-{context}']
= Versions and images overview

The Cluster Operator embeds knowledge of different Kafka versions, but not of the corresponding images in which those versions are provided.
Using the `STRIMZI_KAFKA_IMAGES` environment variable, the Cluster Operator is configured with a mapping between the Kafka version and the image to be used when that version is requested in a given `Kafka` resource.

Each `Kafka` resource can be configured with a `Kafka.spec.kafka.version`. 
If `Kafka.spec.kafka.image` is not configured then the default image for the given version will be used. 
If `Kafka.spec.kafka.image` is given, this overrides the default.

WARNING: The Cluster Operator cannot validate that an image actually contains a Kafka broker of the expected version. 
Take care to ensure that the given image corresponds to the given Kafka version.
