protoutil: add support for converting arbitrary protobuf messages into structs (#3106)

pkg/protoutil/struct.go

@@ -5,6 +5,8 @@ import (
 	"fmt"
 	"reflect"
 
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/types/known/structpb"
 )
 
@@ -45,6 +47,15 @@ func ToStruct(value interface{}) *structpb.Value {
 		return NewStructNumber(float64(v))
 	}
 
+	if msg, ok := value.(proto.Message); ok {
+		bs, _ := protojson.Marshal(msg)
+		var s structpb.Struct
+		_ = protojson.Unmarshal(bs, &s)
+		return &structpb.Value{
+			Kind: &structpb.Value_StructValue{StructValue: &s},
+		}
+	}
+
 	rv := reflect.ValueOf(value)
 	switch rv.Kind() {
 	case reflect.Slice:

pkg/protoutil/struct_test.go

@@ -3,6 +3,8 @@ package protoutil
 import (
 	"testing"
 
+	"google.golang.org/protobuf/types/known/apipb"
+
 	"github.com/pomerium/pomerium/internal/testutil"
 )
 
@@ -28,6 +30,7 @@ func TestToValue(t *testing.T) {
 		{"uint64", uint64(1), "1"},
 		{"[]interface{}", []interface{}{1, 2, 3, 4}, `[1,2,3,4]`},
 		{"map[string]interface{}", map[string]interface{}{"k1": "v1", "k2": "v2"}, `{"k1":"v1","k2":"v2"}`},
+		{"Message", &apipb.Method{Name: "example"}, `{"name": "example"}`},
 	}
 	for _, tc := range testCases {
 		tc := tc