Remove deprecated "type" field from the CPU, Memory, Datadog scalers metadata

[amirschw]

Proposal

In #2309 we added the global metricType field to all scalers.

Specific scalers (CPU, Memory, Datadog) already supported different metric types using their metadata type field, which we deprecated in favor of the new global field. The deprecated field should be removed in a future release.

Use-Case

No response

Anything else?

More details in this discussion

[tomkerkhove]

Was the deprecation added to our changelog & docs?

[amirschw]

It was added to the scalers' docs and we also log a warning when the deprecated field is used

[tomkerkhove]

That's OK, let's make sure it is in the changelog as well then.

[amirschw]

Added here: #2848

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.

[JorTurFer]

When are we going to remove this? maybe we could follow k8s deprecation policies, WDYT?

[tomkerkhove]

When we do KEDA v3.0 because this is a breaking change.

[zroubalik]

We are still v1alpha1 so I don't think we need to wait till v3.0 and actually I wouldn't like to wait. What about deprecation period of 3 releases?

[tomkerkhove]

Fair enough, but there are a lot more of them AFAIK so better build a whole list.

Another approach is introduce version per scaler for this to have more granular control (see #613)

[JorTurFer]

Based on our deprecation policy, we should have removed this in v2.9, so I mark it for v2.10

[tomkerkhove]

@JorTurFer No we are not allowed to do this: https://github.com/kedacore/governance/blob/main/DEPRECATIONS.md#autoscaling-triggers-and-their-metadata

[JorTurFer]

you're right! Thanks for correct me 🙇

[wozniakjan]

per #6229, for CPU and memory, this will actually be 2.18 :)