pkg/

Shared libraries

Generic Executor

Executor simplifies synchronization logic for Kubernetes API resources. It exposes simple methods to control, fine-tune, and handle resource lifecycle. Used for implementation of child resources managed by Plant Operator. A bit more work could be invested to fine-tune and "prettify" the interfaces for more standardized usage.

Refer to pkg/resource/executor.go for info.

Object comparison

Generic derivative diff-er

This approach was used to monitor managed object changes to predefined values. Complexities aside, it performs well, but needs to be further explored and tested to verify behaviour.

// expected defined somewhere
expectedSpecsMap, _ := runtime.DefaultUnstructuredConverter.ToUnstructured(&expected.Spec)
receivedSpecsMap, _ := runtime.DefaultUnstructuredConverter.ToUnstructured(&received.Spec)

// check if fields that expected CONTAINS are semantically equal to ones received has
if !equality.Semantic.DeepDerivative(expectedSpecsMap, receivedSpecsMap) {
    // object was updated
}

Refer to pkg/utils/diff.go for info.

Alternative idea: Selective object comparator

For non-transformative and selective approach to comparison, objects that contain fields with non-zero default values, or for granular comparison. Think: selective, exact, close, or not really. Example: Structure that contains a lot of fields, but we are interested in specific ones to avoid dynamic injection checks.

Refer to pkg/utils/map.go for PoC rundown.

Extends https://github.com/cisco-open/k8s-objectmatcher

• Let expected and actual be two objects which are marshall-able or reflect-able
• Recurse through the objects to create field map with names and types
• Compare to Options by depth and type, prioritize Exclusion by default, but offer options for filtering
• Expose following options for comparison:
  • WithFields(...string) => e.g. WithFields(".Spec.[]Ports.*", ".Spec.Type")
  • WithoutFields(...string) => e.g. WithoutFields(".Spec.[]Ports.NodePort", ".Spec.IPFamilies")
• Invoked as Compare(expected, actual, ...Options) and implements:
  • Equal() bool - returns if they are equal
  • Error() error - helps catch runtime errors, but pririotized through: base types, transforms, option misses and paradox cases.