There have been a lot of questions about how operator fits in with installer and the upcoming Istio 1.2 release. Let me clarify:
- istio-installer will be the fully-tested, preferred method for production installation.
- we plan to release a preview version of the operator at the same time.
- operator will use the same charts and general approach to upgrades (co-resident versions) as installer.
- both installer and operator will use kustomize style overlays for specializing the rendered charts, but operator will not use kustomize itself.
The differences between the two will be:
- operator uses a CRD and can function either as an installer but also to dynamically update the install based on the CRD (“tiller like” mode)
- operator has a new API in addition to values.yaml. This API replaces the k8s resource definitions in values.yaml with a more direct passthrough to k8s approach.
- operator will do validation of values.yaml and the new API.
- we’re still discussing what else, if anything, we might want to expose through the operator API rather than passing through to values.yaml
- overlay spec is going to a bit different to kustomize. kustomize is a tool not a library, so we’re creating our own overlay mechanism that fits better with using a CRD for the operator.