Transformations (#3174)
Adds the ability to provide `transformations` to modify the properties and resource options that will be used for any child resource of a component or stack.
This offers an "escape hatch" to modify the behaviour of a component by peeking behind it's abstraction. For example, it can be used to add a resource option (`additionalSecretOutputs`, `aliases`, `protect`, etc.) to a specific known child of a component, or to modify some input property to a child resource if the component does not (yet) expose the ability to control that input directly. It could also be used for more interesting scenarios - such as:
1. Automatically applying tags to all resources that support them in a stack (or component)
2. Injecting real dependencies between stringly-referenced resources in a Helm Chart
3. Injecting explicit names using a preferred naming convention across all resources in a stack
4. Injecting `import` onto all resources by doing a lookup into a name=>id mapping
Because this feature makes it possible to peek behind a component abstraction, it must be used with care in cases where the component is versioned independently of the use of transformations. Also, this can result in "spooky action at a distance", so should be used judiciously. That said - this can be used as an escape hatch to unblock a wide variety of common use cases without waiting on changes to be made in a component implementation.
Each transformation is passed the `resource`, `name`, `type`, `props` and `opts` that are passed into the `Resource` constructor for any resource descended from the resource that has the transformation applied. The transformation callback can optionally return alternate versions of the `props` and `opts` to be used in place of the original values provided to the resource constructor.
Fixes #2068.
2019-09-29 18:27:37 +00:00
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name: transformations_simple
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