Representing Tree Like data structure in terraform

[parweza]

Terraform Version

Terraform v0.11.7

Representing Tree Like data structure in terraform

Hi,
I am a terraform provider developer and was trying to model following (go representation of data) as terraform resource schema but am not able to do so (terraform validation goes in infinite recursion).
Is it possible to model the following in terraform. if yes , Can you please point me some documentation?

type Model struct {

	FieldType ModelTypeEnum 

	
	FieldName *string


	IsArray *bool 

	Properties []Model 
}

[apparentlymart]

Hi @parweza!

Unfortunately at this time the provider SDK does not support a recursive schema, since some of the operations it does involve traversing the schema tree and -- as you've seen -- there's no guard for cycles.

I'm not sure what's best here with Terraform's current capabilities. If you can share a little more about the underlying system you're working with that might help us come up with some other ideas or "creative" workarounds.

As for making this possible in future: this'd be non-trivial because the provider schema must be sent over the plugin RPC channel and the serialization format we are using (soon to be protobuf in 0.12 and later) does not support recursive data structures itself. However, we'll leave this issue here to remind us of it and consider ways we might make it work in a future release, which'll probably involve a change to the provider RPC protocol.

[mingfang]

Recursive structures is a real requirement.
If protobuf doesn't support recursive structures then maybe that should not be used in 0.12, no?

[paultyng]

I believe the only way to accomplish this now in 0.12 is dynamic type support, linking this to #248

[paultyng]

This also may be solved by direct support in #261 .

Unfortunately, per Martin's comments above, I don't think this will be possible as TF core does not support any sort of recursive type mechanism.

[ghost]

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