buildkit example which prints output of intermediate steps

buildkitop.go

package main

import (
	"bufio"
	"flag"
	"log"
	"os"
	"strings"

	"github.com/moby/buildkit/client/llb"
)

const (
	defaultImage = "docker.io/library/alpine:latest"
)

func main() {

	scriptFile := flag.String("f", "", "input file")
	flag.Parse()

	if *scriptFile == "" {
		log.Fatal("requires input file", *scriptFile)
		os.Exit(1)
	}

	file, err := os.Open(*scriptFile)
	if err != nil {
		log.Fatal("cannot open file : ", *scriptFile)
		os.Exit(1)
	}
	defer file.Close()

	scanner := bufio.NewScanner(file)
	scanner.Scan()
	baseImage := scanner.Text()
	if baseImage == "" {
		baseImage = defaultImage
	}
	bk := buildkit(baseImage)

	for scanner.Scan() {
		cmd := scanner.Text()
		if strings.HasPrefix(cmd, "#") {
			continue
		}
		log.Println(cmd)
		out := bk.Run(llb.Shlex(cmd)).Root() // debug output

		dt, err := out.Marshal()
		if err != nil {
			panic(err)
		}
		llb.WriteTo(dt, os.Stdout)
		bk = out
	}
}

func goBuildBase(baseImage string) llb.State {
	goBase := llb.Image(baseImage)

	return goBase.
		AddEnv("http_proxy", os.Getenv("http_proxy")).
		AddEnv("https_proxy", os.Getenv("https_proxy")).
		Run(llb.Shlex("echo \"Buildkit Shell\"")).Root()
}

func buildkit(baseImage string) llb.State {
	return goBuildBase(baseImage)
}

input example

docker.io/library/golang:latest
#echo hello
ip route
#/usr/bin/apt-get update  
#/usr/bin/apt-get install -y tcpdump
#/usr/bin/apt-get install vim
ping -v -c10 172.20.20.50
#ping -v -c4 172.19.0.3
#ip addr
whereis tcpdump
#mv /usr/sbin/tcpdump /usr/bin/tcpdump
#/usr/bin/curl http://www.google.com
#/usr/bin/tcpdump -i enp1s0 -c 1