howItWorks.md

How does kustomize build work

Call stack when running kustomize build, with links to code.

Run build

• RunBuild
  • MakeKustomizer
  • Run: performs a kustomization. It uses its internal filesystem reference to read the file at the given path argument, interpret it as a kustomization.yaml file, perform the kustomization it represents, and return the resulting resources.
    • Create factories
      • tranformer.NewFactoryImpl
      • resmap.NewFactory
        • resource.NewFactory
          • kustruct.NewKunstructuredFactoryImpl
      • loader.NewLoader
      • validator.NewKustValidator
    • NewKustTarget
    • Load
    • MakeCustomizeResMap: details in next section
  • emitResources

Make resource map

• makeCustomizeResMap
  • AccumulateTarget: returns a new ResAccumulator, holding customized resources and the data/rules used to do so. The name back references and vars are not yet fixed.
    • accummulateResources: fills the given resourceAccumulator with resources read from the given list of paths.
    • Merge config from builtin and CRDs
    • runGenerators
      • configureBuiltinGenerators
        • ConfigMapGenerator
        • SecretGenerator
      • configureExternalGenerators
      • Iterate all generators
    • runTransfomers
      • configureBuiltinTransformers
        • PatchStrategicMergeTransformer
        • PatchTransformer
        • NamespaceTransformer
        • PrefixSuffixTransformer
        • LabelTransformer
        • AnnotationsTransformer
        • PatchJson6902Transformer
        • ReplicaCountTransformer
        • ImageTagTransformer
      • configureExternalTransformers
    • MergeVars
  • The following steps must be done last, not as part of the recursion implicit in AccumulateTarget.
    • addHashesToNames
    • FixBackReferences: Given that names have changed (prefixs/suffixes added), fix all the back references to those names.
    • ResolveVars