Support way to provide custom ContextProvider

[michirue]

• I'm submitting a ...

  • 🪲 bug report
  • 🚀 feature request
  • 📚 construct library gap
  • ☎️ security issue or vulnerability => Please see policy
  • ❓ support request => Please see note at the top of this template.

• What is the expected behavior (or behavior of feature suggested)?

In order to resolve arbitrary data from any type of resource in the AWS account the availableContextProvider map should be extendable with custom implementations. (In my current situation I would like to resolve the ARN/ID of a Cognito user pool based on its name like it's available for hosted zones or VPCs.)

One way this could be achieved is to make the provider property on MissingContext a string or function that returns a promise for a string. Then use the provider function directly or resolve from map if value is a string in provideContextValues. Setting up a custom provider could be as easy as calling this.reportMissingContext(...) with a key and function in a stack constructor.

Another way would be to provide an API to modify the the actual availableContextProvider list. It's probably more difficult as it's a static setup right now and I couldn't find any extension points around the "context provider".

Let me know what you think or if you have similar plans already in mind.

[eladb]

This is a very interesting idea. I am transferring this to the RFC repo. Please follow the RFC Repo README in order to submit this as an RFC.

[eladb]

Duplicate #18