list all gce instances authenticating with the current gcloud configuration

instances.go

package main

import (
	"context"
	"flag"
	"fmt"
	"github.com/binxio/gcloudconfig"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/compute/v1"
	"google.golang.org/api/option"
	"log"
)

// list instances
func main() {
	var err error
	var credentials *google.Credentials

	name := flag.String("configuration", "", "`name` of the configuration to use")
	project := flag.String("project", "", "`id` of the project to query")
	flag.Parse()

	if credentials, err = gcloudconfig.GetCredentials(*name); err != nil {
		log.Fatal(err)
	}
	if project == nil || *project == "" {
		project = &credentials.ProjectID
	}

	if *project == "" {
		log.Printf("%v", credentials)
		log.Fatal("no -project specified")
	}

	computeService, err := compute.NewService(context.Background(), option.WithCredentials(credentials))
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("instances in %s\n", *project)

	token := ""
	for {
		var list *compute.InstanceAggregatedList
		if list, err = computeService.Instances.AggregatedList(*project).PageToken(token).Do(); err != nil {
			log.Fatal(err)
		}

		for zone, instances := range list.Items {
			for _, instance := range instances.Instances {
				fmt.Printf("%s %s %s\n", instance.Name, zone, instance.Status)
			}
		}

		if token = list.NextPageToken; token == "" {
			break
		}
	}
}