Elastic Stack 9.0 will drop the -ubi suffix

[pebrc]

Starting with release 9.0 stack container images will no longer come with a -ubi suffix. Instead the default image will be UBI based and there will be wolfi variants with a dedicated suffix.

We need to:

• adjust the defaulting to -ubi when the --ubi-only flag is set
• test the upgrade path on OLM throrogly
• revisit the usefulness of the --ubi-only for stack 9.0 (maybe at least log a warnign)

cloud-on-k8s/cmd/manager/main.go

Lines 516 to 519 in 3cf131d

	if viper.IsSet(operator.UBIOnlyFlag) {
	err := fmt.Errorf("must not combine %s and %s flags", operator.UBIOnlyFlag, operator.ContainerSuffixFlag)
	log.Error(err, "Illegal flag combination")
	return err

cloud-on-k8s/pkg/controller/common/container/container.go

Lines 84 to 87 in 3cf131d

	useUBISuffix := containerSuffix == UBISuffix
	// use an UBI suffix for maps server image or any image in UBI mode
	if useUBISuffix || isOlderMapsServerImg(img, ver) {
	suffix = getUBISuffix(ver)

[alpar-t]

@pebrc While the default images are becoming UBI based, we are not planning on dropping the -ubi suffix, e.g. elasticsearch and elasticsearch-ubi will both be available and be the exact same image.

[pebrc]

Thanks @alpar-t I think what we need to decide then if we should move the new suffixless version when a customer is requesting UBI images with ECK 3.0 so that you can eventually stop producing the ones with the explicit -ubi suffix.

[pebrc]

@kvalliyurnatt I see you assigned yourself. I think #8480 would be one approach that we could generalise a bit for all images (with exception for the ones that no longer supported in 9.0: enterprisesearch and journalbeat)