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89 lines
3.0 KiB
Go
89 lines
3.0 KiB
Go
// Copyright 2019 The Kubernetes Authors.
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// SPDX-License-Identifier: Apache-2.0
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// Package merge contains libraries for merging fields from one RNode to another
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// RNode
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package merge3
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import (
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"sigs.k8s.io/kustomize/kyaml/yaml"
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"sigs.k8s.io/kustomize/kyaml/yaml/walk"
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)
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const Help = `
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Description:
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merge3 identifies changes between an original source + updated source and merges the result
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into a destination, overriding the destination fields where they have changed between
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original and updated.
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### Resource MergeRules
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- Resources present in the original and deleted from the update are deleted.
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- Resources missing from the original and added in the update are added.
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- Resources present only in the dest are kept without changes.
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- Resources present in both the update and the dest are merged *original + update + dest => dest*.
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### Field Merge Rules
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Fields are recursively merged using the following rules:
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- scalars
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- if present in either dest or updated and 'null', clear the value
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- if unchanged between original and updated, keep dest value
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- if changed between original and updated (added, deleted, changed), take the updated value
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- non-associative lists -- lists without a merge key
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- if present in either dest or updated and 'null', clear the value
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- if unchanged between original and updated, keep dest value
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- if changed between original and updated (added, deleted, changed), take the updated value
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- map keys and fields -- paired by the map-key / field-name
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- if present in either dest or updated and 'null', clear the value
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- if present only in the dest, it keeps its value
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- if not-present in the dest, add the delta between original-updated as a field
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- otherwise recursively merge the value between original, updated, dest
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- associative list elements -- paired by the associative key
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- if present only in the dest, it keeps its value
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- if not-present in the dest, add the delta between original-updated as a field
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- otherwise recursively merge the value between original, updated, dest
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### Associative Keys
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Associative keys are used to identify "same" elements within 2 different lists, and merge them.
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The following fields are recognized as associative keys:
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` + "[`mountPath`, `devicePath`, `ip`, `type`, `topologyKey`, `name`, `containerPort`]" + `
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Any lists where all of the elements contain associative keys will be merged as associative lists.
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`
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func Merge(dest, original, update *yaml.RNode) (*yaml.RNode, error) {
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// if update == nil && original != nil => declarative deletion
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return walk.Walker{Visitor: Visitor{},
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Sources: []*yaml.RNode{dest, original, update}}.Walk()
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}
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func MergeStrings(dest, original, update string) (string, error) {
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srcOriginal, err := yaml.Parse(original)
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if err != nil {
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return "", err
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}
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srcUpdated, err := yaml.Parse(update)
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if err != nil {
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return "", err
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}
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d, err := yaml.Parse(dest)
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if err != nil {
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return "", err
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}
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result, err := Merge(d, srcOriginal, srcUpdated)
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if err != nil {
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return "", err
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}
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return result.String()
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}
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