OptionalAttributes are not optional

[bschaeffer]

terraform-plugin-go version

v0.3.0

Relevant provider source code

package main

import (
	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
	"github.com/hashicorp/terraform-plugin-go/tftypes"
)

var (
	objType = tftypes.Object{
		AttributeTypes: map[string]tftypes.Type{
			"id":   tftypes.Number,
			"name": tftypes.String,
		},
		OptionalAttributes: map[string]struct{}{
			"name": struct{}{},
		},
	}
)

func main() {
	value := tftypes.NewValue(objType, map[string]tftypes.Value{
		"id":   tftypes.NewValue(tftypes.Number, 1),
	})

	_, err := tfprotov5.NewDynamicValue(value.Type(), value)
	if err != nil {
		panic(err)
	}
}

Terraform Configuration Files

Unrelated

Expected Behavior

I am able to create a DyanmicValue without error.

Actual Behavior

panic: AttributeName("name"): no value set

Steps to Reproduce

Run the provided script.

References

• Possibly related to Unable to Unmarshal RawState to a type with OptionalAttributes  #82

[bschaeffer]

You can overcome this by instead supplying a nil Value, but its not super clear that was the solution

tftypes.NewValue(tftypes.String, nil)

Though I am not sure if that's the same thing as making sure you don't store in state any attributes the user hasn't explicitly provided as config input. How to respect the users desire not to track an attribute in state is what brought me here.

[alexsomesan]

Plus one on this. It seems we're hitting this in the Kubernetes alpha provider too.

Here's my version of a repro snippet:

package main

import (
	"log"

	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
	"github.com/hashicorp/terraform-plugin-go/tftypes"
)

func main() {
	ot := tftypes.Object{
		AttributeTypes: map[string]tftypes.Type{
			"a": tftypes.String,
			"b": tftypes.String,
		},
		OptionalAttributes: map[string]struct{}{
			"b": {},
		},
	}

	val := tftypes.NewValue(ot, map[string]tftypes.Value{
		"a": tftypes.NewValue(tftypes.String, "foo"),
	})

	dval, err := tfprotov5.NewDynamicValue(ot, val)
	if err != nil {
		log.Fatalf("NewDynamicValue error: %s", err)
	}

	log.Printf("MsgPack: %x\n", dval.MsgPack)

	nval, err := dval.Unmarshal(ot)
	if err != nil {
		log.Fatalf("ValueFromMsgPack error: %s", err)
	}

	log.Printf("%+v\n", nval)
}

[paddycarver]

I think this is working as intended: optional attributes are about what the practitioner has to set in the config, they don't really influence what gets set in state. Is the request here to optionally not track things in state? Does setting things to null not fulfill this need? Or is it just about not needing to set things to null explicitly when creating the objects?

[bschaeffer]

@paddycarver I think the request here is maybe for more documentation... I came to the solution of tftypes.NewValue(tftypes.String, nil) on my own (or maybe reading other provider code), not through docs or anything.

Having said that, the docs in this code base have been 💯 in all other cases.