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merge3.md

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Merge (3-way)

3-way merge identifies changes between an original source + updated source and merges the result into a destination, overriding the destination fields where they have changed between original and updated.

Resource MergeRules

  • Resources present in the original and deleted from the update are deleted.
  • Resources missing from the original and added in the update are added.
  • Resources present only in the dest are kept without changes.
  • Resources present in both the update and the dest have their fields merged with the destination.

Field Merge Rules

Fields are recursively merged using the following rules:

  • scalars

    • if present in either dest or updated and null, clear the value
    • if unchanged between original and updated, keep dest value
    • if changed between original and updated (added, deleted, changed), take the updated value

  • non-associative lists -- lists without a merge key

    • if present in either dest or updated and null, clear the value
    • if unchanged between original and updated, keep dest value
    • if changed between original and updated (added, deleted, changed), take the updated value

  • map keys and fields -- paired by the map-key / field-name

    • if present in either dest or updated and null, clear the value
    • if present only in the dest, it keeps its value
    • if not-present in the dest, add the delta between original-updated as a field
    • otherwise recursively merge the value between original, updated, dest

  • associative list elements -- paired by the associative key

    • if present only in the dest, it keeps its value
    • if not-present in the dest, add the delta between original-updated as a field
    • otherwise recursively merge the value between original, updated, dest

Associative Keys

Associative keys are used to identify "same" elements within 2 different lists, and merge them. The following fields are recognized as associative keys:

[mountPath, devicePath, ip, type, topologyKey, name, containerPort]

Any lists where all of the elements contain associative keys will be merged as associative lists.