buildctl: add dump

Signed-off-by: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>

cmd/buildctl/dump.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"io"
+	"log"
+	"os"
+
+	"github.com/davecgh/go-spew/spew"
+	digest "github.com/opencontainers/go-digest"
+	"github.com/pkg/errors"
+	"github.com/tonistiigi/buildkit_poc/client/llb"
+	"github.com/tonistiigi/buildkit_poc/solver/pb"
+	"github.com/urfave/cli"
+)
+
+var dumpCommand = cli.Command{
+	Name:   "dump",
+	Usage:  "dump LLB in human-readable format. LLB must be passed via stdin. This command does not require the daemon to be running.",
+	Action: dumpLLB,
+}
+
+func dumpLLB(clicontext *cli.Context) error {
+	ops, err := loadLLB(os.Stdin)
+	if err != nil {
+		return err
+	}
+	log.Print(spew.Sdump(ops))
+	return nil
+}
+
+type llbOp struct {
+	Op     pb.Op
+	Digest digest.Digest
+}
+
+func loadLLB(r io.Reader) ([]llbOp, error) {
+	bs, err := llb.ReadFrom(r)
+	if err != nil {
+		return nil, err
+	}
+	var ops []llbOp
+	for _, dt := range bs {
+		var op pb.Op
+		if err := (&op).Unmarshal(dt); err != nil {
+			return nil, errors.Wrap(err, "failed to parse op")
+		}
+		dgst := digest.FromBytes(dt)
+		ops = append(ops, llbOp{Op: op, Digest: dgst})
+	}
+	return ops, nil
+}

cmd/buildctl/main.go

@@ -29,6 +29,7 @@ func main() {
 	app.Commands = []cli.Command{
 		diskUsageCommand,
 		buildCommand,
+		dumpCommand,
 	}
 
 	app.Before = func(context *cli.Context) error {