feat(core): track and apply resource changes through deep diffing #173
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a-hilaly
commented
Dec 23, 2024
| @@ -80,6 +81,7 @@ func NewResourceGroupReconciler( | |||
| func (r *ResourceGroupReconciler) SetupWithManager(mgr ctrl.Manager) error { | |||
| return ctrl.NewControllerManagedBy(mgr). | |||
| For(&v1alpha1.ResourceGroup{}). | |||
| WithEventFilter(predicate.GenerationChangedPredicate{}). | |||
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i've observed some weird infinite-loops during integration test logs... While i know that predicate event filters can fix it, i'm still slightly hesitant, it should be needed..
Need to do some careful sleuthing here
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Up until now, we weren't really doing proper diffing when deciding whether to update managed resources - we just marked everything as "SYNCED". This patch adds a new delta package that does a proper deep comparison between desired and observed resource states, being careful about all the k8s metadata fields that we should ignore during comparisons (e.g `metadata.generation`, `metadta.revision` etc...) A key design aspect of this implementation is that `kro` only diffs fields that are explicitly defined in `ResourceGroup` - any field that is defaulted by other controllers or mutating webhooks are ignored. This ensures `kro` coexists seamlessly with other reconciliation systems without fighting over field ownership. The delta `Compare` function takes the desired and observed `unstructured.Unstructured` objects and returns a list of structured "differences", where each difference contains the full path to the changed field and its desired/observed values. It recursively walks both object trees in parallel, building pathstring like `spec.containers[0].image` to precisely identify where values diverge. The comparison handles type mismatches, nil vs empty maps/slices, value differences etc... Also patch also adds integration tests in suites/core for generic resource updates and in suites/ackekscluster for EKS-clutser-specific version updates. note that in both tests we mainly rely on the `metadata.revision` to validate that indeed the controller did make an spec update call.
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michaelhtm
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Dec 27, 2024
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| if annotations, exists := metadata["labels"].(map[string]interface{}); exists { | ||
| if len(annotations) == 0 { | ||
| delete(metadata, "labels") | ||
| } | ||
| } |
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nit:
Suggested change
| if annotations, exists := metadata["labels"].(map[string]interface{}); exists { | |
| if len(annotations) == 0 { | |
| delete(metadata, "labels") | |
| } | |
| } | |
| if labels, exists := metadata["labels"].(map[string]interface{}); exists { | |
| if len(labels) == 0 { | |
| delete(metadata, "labels") | |
| } | |
| } |
| } | ||
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| // ignoredFields are Kubernetes metadata fields that should not trigger updates. | ||
| var ignoredFields = []string{ |
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Will we add more fields to ignore here? or just the ones in metadata?
Because instead i'm thinking we can call it ignoredMetadataFields...
| } | ||
|
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| for _, field := range ignoredFields { | ||
| delete(metadata, field) |
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Up until now, we weren't really doing proper diffing when deciding whether to update
managed resources - we just marked everything as "SYNCED". This patch adds a new delta
package that does a proper deep comparison between desired and observed resource
states, being careful about all the k8s metadata fields that we should ignore during
comparisons (e.g
metadata.generation,metadta.revisionetc...)A key design aspect of this implementation is that
kroonly diffs fields that areexplicitly defined in
ResourceGroup- any field that is defaulted by othercontrollers or mutating webhooks are ignored. This ensures
krocoexists seamlesslywith other reconciliation systems without fighting over field ownership.
The delta
Comparefunction takes the desired and observedunstructured.Unstructuredobjects and returns a list of structured "differences", where each difference contains
the full path to the changed field and its desired/observed values. It recursively
walks both object trees in parallel, building pathstring like
spec.containers[0].imageto precisely identify where values diverge. The comparison handles type mismatches,
nil vs empty maps/slices, value differences etc...
Also patch also adds integration tests in suites/core for generic resource
updates and in suites/ackekscluster for EKS-clutser-specific version updates. note that
in both tests we mainly rely on the
metadata.revisionto validate that indeed thecontroller did make an spec update call.
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