protoflag

protoflag is a tiny Go library that can turn any Protocol Buffer message into a set of command‑line flags. It works both with the standard flag package and with the popular pflag package, handling nested fields, messages, lists and maps automatically.

Looking for a package that works similarly but on any Go type? Check jsonflag.

Adding to project

First, use go get to download and add the latest version of the library to the project.

go get -u github.com/daishe/protoflag

Then include in your source code.

import "github.com/daishe/protoflag"

Usage example (with standard go flag package)

package main

import (
	"flag"
	"fmt"
	"net"
	"net/http"
	"net/http/httputil"
	"net/url"
	"os"
	"strconv"

	"google.golang.org/protobuf/proto"
	"google.golang.org/protobuf/reflect/protoreflect"
	"google.golang.org/protobuf/types/descriptorpb"

	"github.com/daishe/protoflag"
	typesv1 "github.com/daishe/protoflag/examples/simplecurl/types/v1"
)

func main() {
	// config with default values
	config := typesv1.Config_builder{
		Url: typesv1.Url_builder{
			Scheme: "http",
			Host:   "localhost",
			Port:   8080,
		}.Build(),
	}.Build()

	usage := func(path []protoreflect.FieldDescriptor) string {
		opts, ok := path[len(path)-1].Options().(*descriptorpb.FieldOptions)
		if !ok || opts == nil {
			return ""
		}
		usage, ok := proto.GetExtension(opts, typesv1.E_Usage).(string)
		if !ok {
			return ""
		}
		return usage
	}

	fs := flag.NewFlagSet("", flag.ExitOnError) // you can also add it directly to the root flag set
	for _, val := range protoflag.Recursive(config) {
		fs.Var(val, protoflag.JSONName(val.Path()), usage(val.Path()))
	}
	if err := fs.Parse(os.Args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "Arguments parsing error: %v\n", err)
		os.Exit(1)
	}

	u := url.URL{
		Scheme: config.GetUrl().GetScheme(),
		Host:   net.JoinHostPort(config.GetUrl().GetHost(), strconv.FormatInt(int64(config.GetUrl().GetPort()), 10)),
		Path:   config.GetUrl().GetPath(),
	}

	resp, err := http.Get(u.String()) //nolint:noctx // this is just an example
	if err != nil {
		fmt.Fprintf(os.Stderr, "Doing request error: %v\n", err)
		os.Exit(1)
	}
	defer resp.Body.Close()

	if config.GetVerbose() {
		respBytes, err := httputil.DumpResponse(resp, true)
		if err != nil {
			fmt.Fprintf(os.Stderr, "Dumping response error: %v\n", err)
			os.Exit(1) //nolint:gocritic // this is just an example
		}
		fmt.Printf("%s\n", respBytes)
	}
}

License

The project is released under the Apache License, Version 2.0. See the full LICENSE file for the complete terms and conditions.