Further down the skycfg/protobof/envoy rabbit hole

main.go

package main

import (
	"context"
	"fmt"
	"reflect"

	docopt "github.com/docopt/docopt-go"

	"github.com/gogo/protobuf/jsonpb"
	gogo_proto "github.com/gogo/protobuf/proto"
	proto "github.com/golang/protobuf/proto"
	_ "github.com/golang/protobuf/ptypes/wrappers"
	"github.com/stripe/skycfg"
	yaml "gopkg.in/yaml.v2"

	_ "github.com/envoyproxy/go-control-plane/envoy/admin/v2alpha"
	_ "github.com/envoyproxy/go-control-plane/envoy/api/v2"
	_ "github.com/envoyproxy/go-control-plane/envoy/config/bootstrap/v2"
)

type protoRegistry struct{}

func (*protoRegistry) UnstableProtoMessageType(name string) (reflect.Type, error) {
	if t := proto.MessageType(name); t != nil {
		return t, nil
	}
	if t := gogo_proto.MessageType(name); t != nil {
		return t, nil
	}
	return nil, nil
}

func (*protoRegistry) UnstableEnumValueMap(name string) map[string]int32 {
	if ev := proto.EnumValueMap(name); ev != nil {
		return ev
	}
	if ev := gogo_proto.EnumValueMap(name); ev != nil {
		return ev
	}
	return nil
}

func main() {

	usage := `envoy-proto: creates an envoy configuration from a skycfg file

Usage:
  envoy-proto <input-file>
  envoy-proto -h | --help

Options:
  <input-file>  skycfg file to be read
  -h --help     Show this screen.`

	arguments, _ := docopt.ParseDoc(usage)

	ctx := context.Background()
	config, err := skycfg.Load(ctx, arguments["<input-file>"].(string), skycfg.WithProtoRegistry(&protoRegistry{}))
	if err != nil {
		panic(err)
	}
	messages, err := config.Main(ctx)
	if err != nil {
		panic(err)
	}
	for _, msg := range messages {
		var jsonMarshaler = &jsonpb.Marshaler{OrigName: true}

		marshaled, err := jsonMarshaler.MarshalToString(msg)
		sep := ""
		var yamlMap yaml.MapSlice
		if err := yaml.Unmarshal([]byte(marshaled), &yamlMap); err != nil {
			panic(fmt.Sprintf("yaml.Unmarshal: %v", err))
		}
		yamlMarshaled, err := yaml.Marshal(yamlMap)
		if err != nil {
			panic(fmt.Sprintf("yaml.Marshal: %v", err))
		}
		marshaled = string(yamlMarshaled)
		sep = "---\n"
		fmt.Printf("%s%s\n", sep, marshaled)
	}
}

output.md

Tried to get this working with the UInt32Value protobuf message, per the envoy protobuf xdi:

rm reproducer; go build; ./reproducer uint32_reproducer.sky
[uint32_reproducer.sky:14] dur is <google.protobuf.UInt32Value value:20 >
panic: TypeError: value <google.protobuf.UInt32Value value:20 > (type `google.protobuf.UInt32Value') can't be assigned to type `google.protobuf.UInt32Value'.

goroutine 1 [running]:
main.main()
	/home/spacey/go/src/github.com/pcn/reproducer/main.go:65 +0x64b
spacey@masonjar:~/go/src/github.com/pcn/reproducer$ 

uint32_reproducer.sky

# -*- python -*-
pb = proto.package("google.protobuf")
v2 = proto.package("envoy.api.v2")
v2_cluster = proto.package("envoy.api.v2.cluster")

def duration(dur):
    thresh = v2_cluster.CircuitBreakers.Thresholds(
        max_connections=dur
    )
    return v2.Cluster(thresholds = [thresh])

def main(context):
    dur = proto.from_text(pb.UInt32Value, "value: 20")
    print("dur is {}".format(dur))
    duration(dur)