createbuildlet.go

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"strings"
	"time"

	"golang.org/x/build/buildlet"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	compute "google.golang.org/api/compute/v1"
)

var (
	serial       = flag.Bool("serial", false, "watch serial")
	pauseAfterUp = flag.Bool("pause-after-up", false, "pause for a few seconds (enough to SIGSTOP) after WorkDir returns")
)

func main() {
	flag.Parse()
	ts, err := google.DefaultTokenSource(context.Background())
	if err != nil {
		log.Fatal(err)
	}

	computeSvc, _ := compute.New(oauth2.NewClient(context.TODO(), ts))

	name := fmt.Sprintf("debug-brad-windows-%d", time.Now().Unix())
	log.Printf("Creating %s", name)
	c, err := buildlet.StartNewVM(ts, name, "host-windows-amd64-2012", buildlet.VMOpts{
		Zone:                "us-central1-f",
		ProjectID:           "symbolic-datum-552",
		DeleteIn:            30 * time.Minute,
		OnInstanceRequested: func() { log.Printf("instance requested") },
		OnInstanceCreated: func() {
			log.Printf("instance created")
			if *serial {
				// This is roughly "gcloud compute
				// connect-to-serial-port --zone=us-central1-f
				// $NAME", but in Go and works. For some reason,
				// gcloud doesn't work as a child process and
				// has weird errors.
				go watchSerial(name)
				return
			}
		},
		OnGotInstanceInfo: func() { log.Printf("got instance info") },
	})
	if err != nil {
		log.Fatalf("StartNewVM: %v", err)
	}
	dir, err := c.WorkDir()
	log.Printf("WorkDir: %v, %v", dir, err)
	if *pauseAfterUp {
		log.Printf("Shutting down in 5 seconds...")
		time.Sleep(5 * time.Second)
	}
	if err := c.Close(); err != nil {
		log.Fatalf("Close: %v", err)
	}
	log.Printf("done.")
}

func watchSerial(name string) {
	start := int64(0)
	for {
		sout, err := computeSvc.Instances.GetSerialPortOutput("symbolic-datum-552", "us-central1-f", name).Start(start).Do()
		if err != nil {
			log.Printf("serial output error: %v", err)
			return
		}
		moved := sout.Next != start
		start = sout.Next
		contents := strings.TrimSpace(sout.Contents)
		if contents != "" {
			log.Printf("SERIAL: %s", strings.TrimSpace(sout.Contents))
		}
		if !moved {
			time.Sleep(1 * time.Second)
		}
	}
}