[4.20] OCPBUGS-60083: Fix strategic merge

[mkowalski]

This PR fixes fundamental issue with the previous patch nmstate#1357 that was supposed to introduce strategic merge.

Because we operate on unstructured.Unstructured objects, StrategicMergeFrom was not running correctly as it cannot detect the type of the object. To fix this issue we introduce a conversion to the typed object based on its GroupVersionKind. That way, strategic merge operates on an object with a well-defined type. For any cases where we cannot convert untyped object, we will fallback to the regular merge strategy.

Additionally, we are introducing a function merging metadata for objects type Namespace. This is because those do not have a proper merge strategy defined for their metadata. As a result, strategic merge which involves labels and annotations overrides those as a whole map. Having such a function allows us to properly merge labels and annotations.

[mkowalski]

/hold

[openshift-ci-robot]

@mkowalski: This pull request references Jira Issue OCPBUGS-60083, which is valid. The bug has been moved to the POST state.

7 validation(s) were run on this bug

• bug is open, matching expected state (open)
• bug target version (4.20.0) matches configured target version for branch (4.20.0)
• bug is in the state ASSIGNED, which is one of the valid states (NEW, ASSIGNED, POST)
• release note text is set and does not match the template
• dependent bug Jira Issue OCPBUGS-60455 is in the state Verified, which is one of the valid states (MODIFIED, ON_QA, VERIFIED)
• dependent Jira Issue OCPBUGS-60455 targets the "4.21.0" version, which is one of the valid target versions: 4.21.0
• bug has dependents

Requesting review from QA contact:
/cc @rbbratta

The bug has been updated to refer to the pull request using the external bug tracker.

In response to this:

This PR fixes fundamental issue with the previous patch nmstate#1357 that was supposed to introduce strategic merge.

Because we operate on unstructured.Unstructured objects, StrategicMergeFrom was not running correctly as it cannot detect the type of the object. To fix this issue we introduce a conversion to the typed object based on its GroupVersionKind. That way, strategic merge operates on an object with a well-defined type. For any cases where we cannot convert untyped object, we will fallback to the regular merge strategy.

Additionally, we are introducing a function merging metadata for objects type Namespace. This is because those do not have a proper merge strategy defined for their metadata. As a result, strategic merge which involves labels and annotations overrides those as a whole map. Having such a function allows us to properly merge labels and annotations.

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mkowalski

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[mkowalski]

/test e2e-operator-ovn-ipv4

[openshift-ci]

@mkowalski: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-handler-ovn-ipv4	3b7e207	link	true	/test e2e-handler-ovn-ipv4

Full PR test history. Your PR dashboard.

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[mkowalski]

/hold

The reason is that this code diverges a lot from what we have on master/4.21; I do not want to merge it unless really necessary. Please keep it open with hold in case there is a critical escalation that is affected by this code.

I do not expect one, but you never know.