create LLB state

llb.go

package main

import (
	"context"
	"os"

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

func createLLBState() llb.State {
	base := llb.Image("docker.io/library/alpine")

	base = base.
		File(llb.Mkdir("/tmp/dir", 0755)).
		File(llb.Copy(llb.Local("context"), "README.md", "/tmp/dir/README.md")).
		File(llb.Copy(llb.Local("context"), "README.md", "README.md"))

	anotbase := llb.Image("docker.io/library/alpine:3.6")
	anotbase = anotbase.Run(llb.Shlexf("cp -a /tmp/dir/%s /tmp/dir/%s", "README.md", "README.copy.md")).
		AddMount("/", base)

	return anotbase.Run(llb.Args([]string{"/bin/sh"})).Root()
}

func main() {
	dt, err := createLLBState().Marshal(context.TODO(), llb.LinuxAmd64)
	if err != nil {
		panic(err)
	}
	llb.WriteTo(dt, os.Stdout)
}

# go run main.go | buildctl debug dumb-llb | jq