execution.txt

$ cat list
n1.example.net
n2.example.net

$ ./test --nodes list                                                                                                                                                                               <21:21:44
Discovering nodes .... 2

2 / 2    0s [====================================================================] 100%

n1.example.net

   Timestamp: 1611001344

n2.example.net

   Timestamp: 1611001344


Finished processing 2 / 2 hosts in 688ms

help.txt

./test --help
usage: demo [<flags>]

Small demo app

Flags:
      --help             Show context-sensitive help (also try --help-long and --help-man).
      --verbose          Be verbose
  -F, --wf=WF ...        Match hosts with a certain fact
  -C, --wc=WC ...        Match hosts with a certain configuration management class
  -A, --wa=WA ...        Match hosts with a certain Choria agent
  -I, --wi=WI ...        Match hosts with a certain Choria identity
  -W, --with=FILTER ...  Combined classes and facts filter
  -S, --select=EXPR      Match hosts using a expr compound filter
  -T, --target=TARGET    Target a specific sub collective
      --nodes=NODES      List of nodes to interact with in JSON, YAML or TEXT formats
      --dm=DM            Sets a discovery method (mc, choria)
      --discovery-timeout=SECONDS  
                         Timeout for doing discovery

main.go

package main

import (
	"context"
	"os"

	"gopkg.in/alecthomas/kingpin.v2"

	"github.com/choria-io/go-choria/choria"
	"github.com/choria-io/go-choria/client/discovery"
	"github.com/choria-io/go-choria/client/rpcutilclient"
)

var (
	opt     *discovery.StandardOptions
	verbose bool
)

func main() {
	app := kingpin.New("demo", "Small demo app").Action(run)
	app.Flag("verbose", "Be verbose").BoolVar(&verbose)

	opt = &discovery.StandardOptions{}
	opt.AddFilterFlags(app)
	opt.AddFlatFileFlags(app)
	opt.AddSelectionFlags(app)

	kingpin.MustParse(app.Parse(os.Args[1:]))
}

func run(_ *kingpin.ParseContext) error {
	fw, err := choria.New(choria.UserConfig())
	if err != nil {
		return err
	}

	opt.SetDefaultsByConfig(fw.Configuration())
	rpcutil, err := rpcutilclient.New(rpcutilclient.Progress(), rpcutilclient.Discovery(&rpcutilclient.MetaNS{
		Options:               opt,
		Agent:                 "rpcutil",
		DisablePipedDiscovery: false,
	}))
	if err != nil {
		return err
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	res, err := rpcutil.Ping().Do(ctx)
	if err != nil {
		return err
	}

	res.RenderResults(os.Stdout, rpcutilclient.TextFormat, rpcutilclient.DisplayDDL, false, false, true, fw.Logger("render"))

	return nil
}