This issue is meant to cover minor upgrades using the operator - that is Service Mesh 3.0 to 3.1 to 3.2, etc... this should cover both in-place and (upstream recommended) canary upgrades, and how our operator can support these.

This is separate from OSSM2 -> 3 migrations, which is covered by this issue: https://issues.redhat.com/browse/OSSM-4110

On canary upgrades, and why they provide value over in-place upgrades:

Istio's concept of revisions and tags allows users to incrementally upgrade their Istio control plane - moving over a smaller portion of services to a new control plane one step at a time, based on tags. This reduces the risks of upgrading a mesh, as users can start by upgrading less critical services and only complete the rest of the upgrade once they are confident of the new control plane and configuration. Even if the upgrade process cannot be reversed, the damage is limited to services where an upgrade attempt has been made.

This has been requested by a few customers and is also consistent with our desire to converge with upstream Istio. Support for canary rollouts is also planned as part of [OLM 1.0|http://example.comhttps://docs.google.com/document/d/1LX4dJMbSmuIMn98tCiBaONmTunWR6zdUJuH-8uZ8Cno/edit.|http://example.com]https//docs.google.com/document/d/1LX4dJMbSmuIMn98tCiBaONmTunWR6zdUJuH-8uZ8Cno/edit.]

This may also aid in any future major version upgrades.

https://istio.io/latest/blog/2021/revision-tags/