Understanding the relationship of tagPrefix and suffix

[jack1902]

I'm trying to understand the tradeoffs of using image.tagPrefix vs image.tag.

I see the helm-chart values.yaml has tagPrefix listed here

strimzi-kafka-operator/helm-charts/helm3/strimzi-kafka-operator/values.yaml

Line 99 in 8e30be3

tagPrefix: ""

But the README.md has the below

I am struggling to find documentation on the tradeoffs of using tagPrefix vs tag. If i use tag, how does that impact upgrades of kafka, if the downstream connect CR has .spec.version: some-future-version does that result in it using the tag defined on the operator regardless?

Where does the suffix come from?

[scholzj]

If you specify some unsupported Kafka version, you should always get an error. So it does not matter what image you have configured.

the main point of the tagPrefix is that many images have the tags consist of several parts - e.g. quay.io/strimzi/kafka:0.43.0-kafka-3.7.0. And the tagPrefix let's you configure the first part of the tag: <tagPrefix>-kafka-3.7.0. The tag on the other hand should configure the whole tag IIRC.

[jack1902]

I understand the suffix won't be used if i use image.tag, but i'm attempting to understand the caveats of using image.tag over image.tagPrefix

[scholzj]

If i set the image.tag (specifically for the kafka-connect) to something such as 3.8.0, but i had set my spec.version within the connect CR to use 3.7.0 would there be any fallout?

The image for Kafka version X should always contain Kafka version X. Otherwise you might run into issues. Connect does not have too many changes. But it can happen that for example some new API call is added in 3.8 that is missing in 3.7. And if you tell the operator to use Kafka 3.8, but give it an image of Kafka 3.7 instead, it would not work when the operator tries to use the new API. So the images should always correspond to the given version.

As I said, configuring the tag is not really useful for the images based on a particular Kafka version. But it is useful for example to configure the UserOperator image as there you have only one image for all Kafka versions.

[jack1902]

Cheers, will ensure that i have internal images for all possible suffixes within a given release. In the case of 0.43.0 above, the connect image suffix of kafka-3.8.0 comes from the .spec.version of the connect CR right?

Based on that, i would need to ensure i have kafka-3.7.0, kafka-3.7.1 and kafka-3.8.0 available internally? (what drives the suffix?)

[scholzj]

In general yes. Of course, the image will be only used if you use given version. So if you know you are only using 3.7.0 and 3.8.0, the 3.7.1 might never be used and while you might need to set it to some value, the actual image might not need to exist. But in general it is easiest to just have all the images available.

[jack1902]

Cheers, thank you for your patience here by the way, will close this out 🙇