main.go

package main

import (
	"context"
	"fmt"
	"os"
	"path/filepath"

	_ "github.com/moby/buildkit/client/connhelper/dockercontainer"

	"github.com/moby/buildkit/client"
	"github.com/moby/buildkit/client/llb"
	"github.com/moby/buildkit/util/appdefaults"
	"github.com/moby/buildkit/util/progress/progresswriter"
	"golang.org/x/sync/errgroup"
)

func main() {
	err := run(context.Background(), false)
	if err != nil {
		fmt.Fprintf(os.Stderr, "err: %s\n", err)
		os.Exit(1)
	}
	err = run(context.Background(), true)
	if err != nil {
		fmt.Fprintf(os.Stderr, "err: %s\n", err)
		os.Exit(1)
	}
}

const (
	busyboxLatest = "busybox:latest@sha256:ae39a6f5c07297d7ab64dbd4f82c77c874cc6a94cea29fdec309d0992574b4f7"
	busyboxGlibc = "busybox:latest@sha256:efa4903894afd1b59358ec0b8dda6959fe9f43f9ba97bc270743fe31aea78d93"
)

func run(ctx context.Context, pass2 bool) error {
	st := llb.Image(busyboxLatest, llb.LinuxAmd64)

	fromImage := llb.Image(busyboxLatest, llb.LinuxAmd64)

	imageRef := busyboxGlibc
	if pass2 {
		imageRef = busyboxLatest
	}
	toImage := llb.Image(imageRef, llb.LinuxAmd64)

	st = st.Run(
		llb.Shlex(`sh -c "diff -rN /from /to > /out/diff.out || true"`),
		llb.AddMount("/from", fromImage, llb.Readonly),
		llb.AddMount("/to", toImage, llb.Readonly),
	).AddMount("/out", llb.Scratch())

	def, err := st.Marshal(ctx)
	if err != nil {
		return err
	}

	addr := os.Getenv("BUILDKIT_HOST")
	if addr == "" {
		addr = appdefaults.Address
	}

	c, err := client.New(ctx, addr, client.WithFailFast())
	if err != nil {
		return err
	}

	pw, err := progresswriter.NewPrinter(context.TODO(), os.Stderr, "auto")
	if err != nil {
		return err
	}
	mw := progresswriter.NewMultiWriter(pw)

	eg, ctx := errgroup.WithContext(ctx)

	cwd, err := os.Getwd()
	if err != nil {
		return err
	}

	outputDir := filepath.Join(cwd, "pass1")
	if pass2 {
		outputDir = filepath.Join(cwd, "pass2")
	}

	eg.Go(func() error {
		solveOpt := client.SolveOpt{
			Exports: []client.ExportEntry{{
				Type:      client.ExporterLocal,
				OutputDir: outputDir,
			}},
		}

		_, err := c.Solve(ctx, def, solveOpt, progresswriter.ResetTime(mw.WithPrefix("", false)).Status())
		return err
	})

	eg.Go(func() error {
		<-pw.Done()
		return pw.Err()
	})

	return eg.Wait()
}