Avoid roundtrip to json when converting Cty to map[string]any

Author: VenelinMartinov

pkg/tfshim/sdk-v2/cty_json.go

@@ -15,14 +15,10 @@
 package sdkv2
 
 import (
-	"bytes"
-	"encoding/json"
 	"strings"
 
-	"github.com/hashicorp/go-cty/cty"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
 	"github.com/hashicorp/terraform-plugin-sdk/v2/terraform"
-	"github.com/pulumi/pulumi/sdk/v3/go/common/util/contract"
 	diff_reader "github.com/pulumi/terraform-diff-reader/sdk-v2"
 
 	shim "github.com/pulumi/pulumi-terraform-bridge/v3/pkg/tfshim"
@@ -67,34 +63,6 @@ func (s v2InstanceState) Object(sch shim.SchemaMap) (map[string]interface{}, err
 	return s.objectV1(sch)
 }
 
-// This is needed because json.Unmarshal uses float64 for numbers by default which truncates int64 numbers.
-func unmarshalJSON(data []byte, v interface{}) error {
-	dec := json.NewDecoder(bytes.NewReader(data))
-	dec.UseNumber()
-	return dec.Decode(v)
-}
-
-// objectFromCtyValue takes a cty.Value and converts it to JSON object.
-// We do not care about type checking the values, we just want to do our best to recursively convert
-// the cty.Value to the underlying value
-//
-// NOTE: one of the transforms this needs to handle is converting unknown values.
-// cty.Value that are also unknown cannot be converted to their underlying value. To get
-// around this we just convert to a sentinel, which so far does not seem to cause any issues downstream
-func objectFromCtyValue(v cty.Value) map[string]interface{} {
-	var path cty.Path
-	buf := &bytes.Buffer{}
-	// The round trip here to JSON is redundant, we could instead convert from cty to map[string]interface{} directly
-	err := marshal(v, v.Type(), path, buf)
-	contract.AssertNoErrorf(err, "Failed to marshal cty.Value to a JSON string value")
-
-	var m map[string]interface{}
-	err = unmarshalJSON(buf.Bytes(), &m)
-	contract.AssertNoErrorf(err, "failed to unmarshal: %s", buf.String())
-
-	return m
-}
-
 // The legacy version of Object used custom Pulumi code forked from TF sources.
 func (s v2InstanceState) objectV1(sch shim.SchemaMap) (map[string]interface{}, error) {
 	obj := make(map[string]interface{})

pkg/tfshim/sdk-v2/instance_state.go

@@ -0,0 +1,56 @@
+package sdkv2
+
+import (
+	"github.com/hashicorp/go-cty/cty"
+	"github.com/pulumi/pulumi/sdk/v3/go/common/util/contract"
+)
+
+func objectFromCtyValue(val cty.Value) map[string]any {
+	return objectFromCtyValueInner(val).(map[string]any)
+}
+
+func objectFromCtyValueInner(val cty.Value) any {
+	contract.Assertf(!val.IsMarked(), "value has marks, so it cannot be serialized")
+	if val.IsNull() {
+		return nil
+	}
+
+	if !val.IsKnown() {
+		return terraformUnknownVariableValue
+	}
+
+	switch {
+	case val.Type().IsPrimitiveType():
+		switch val.Type() {
+		case cty.String:
+			return val.AsString()
+		case cty.Number:
+			return val.AsBigFloat().Text('f', -1)
+		case cty.Bool:
+			return val.True()
+		default:
+			contract.Failf("unsupported primitive type: %s", val.Type().FriendlyName())
+		}
+	case val.Type().IsListType(), val.Type().IsSetType(), val.Type().IsTupleType():
+		l := make([]interface{}, 0, val.LengthInt())
+		it := val.ElementIterator()
+		for it.Next() {
+			_, ev := it.Element()
+			elem := objectFromCtyValueInner(ev)
+			l = append(l, elem)
+		}
+		return l
+	case val.Type().IsObjectType(), val.Type().IsMapType():
+		l := make(map[string]interface{})
+		it := val.ElementIterator()
+		for it.Next() {
+			ek, ev := it.Element()
+			cv := objectFromCtyValueInner(ev)
+			l[ek.AsString()] = cv
+		}
+		return l
+	}
+
+	contract.Failf("unsupported type: %s", val.Type().FriendlyName())
+	return nil
+}