Upgrade the mysqld version and support major version upgrades in vitess-operator

[frouioui]

Feature Description

Here is an outline of what we want to achieve:

• Ease how we upgrade the version of mysqld in Vitess.
• Support mysqld upgrades in vitess-operator.
• Ship a lightweight Docker Image for the mysqld container.
• Enable users to easily select what mysqld version they want to run.
• Bump default 8.0 version to 8.0.34.

The current MySQL version we ship in Vitess is 8.0.30. This version is slightly outdated as there is a more recent (8.0.34) version available. We would like to upgrade to 8.0.34. However, upgrading the MySQL version on a live cluster can be tricky and might require the vitess-operator (or the end-user) to shutdown the mysqld instances with innodb_fast_shutdown=0 to allow for a safe upgrade. The current issue with the vitess-operator is that there is no clear way of knowing the user is about to upgrade the MySQL version when doing an apply. To enable the vitess-operator of knowing that there is a MySQL upgrade incoming, we would like to use a dedicated mysqld Docker Image that is tagged by MySQL version. Just by comparing the tag of the Docker Image the end-user wants to apply, and the current tag used by the deployment, the vitess-operator will be able to decide whether or not to set innodb_fast_shutdown to 0. This will facilitate any future MySQL upgrade, giving the choice to end-users to remain on a specific MySQL version or to move to the new one.

The goal is that instead of using the vitess/lite:latest image for mysql80Compatible in the K8S YAML file, end-users will use i.e. vitess/lite:8.0.34.

Use Case(s)

na