dockerfile: show redirect parser warnings

Signed-off-by: Tonis Tiigi <[email protected]>

client/llb/marshal.go

@@ -39,6 +39,24 @@ func (def *Definition) FromPB(x *pb.Definition) {
 	}
 }
 
+func (def *Definition) Head() (digest.Digest, error) {
+	if len(def.Def) == 0 {
+		return "", nil
+	}
+
+	last := def.Def[len(def.Def)-1]
+
+	var pop pb.Op
+	if err := (&pop).Unmarshal(last); err != nil {
+		return "", err
+	}
+	if len(pop.Inputs) == 0 {
+		return "", nil
+	}
+
+	return pop.Inputs[0].Digest, nil
+}
+
 func WriteTo(def *Definition, w io.Writer) error {
 	b, err := def.ToPB().Marshal()
 	if err != nil {

frontend/dockerfile/builder/build.go

@@ -264,6 +264,11 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 		return nil, errors.Wrapf(err, "failed to marshal local source")
 	}
 
+	defVtx, err := def.Head()
+	if err != nil {
+		return nil, err
+	}
+
 	var sourceMap *llb.SourceMap
 
 	eg, ctx2 := errgroup.WithContext(ctx)
@@ -426,6 +431,7 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 						err = wrapSource(err, sourceMap, el.Location)
 					}
 				}()
+
 				st, img, err := dockerfile2llb.Dockerfile2LLB(ctx, dtDockerfile, dockerfile2llb.ConvertOpt{
 					Target:            opts[keyTarget],
 					MetaResolver:      c,
@@ -449,6 +455,12 @@ func Build(ctx context.Context, c client.Client) (*client.Result, error) {
 					LLBCaps:           &caps,
 					SourceMap:         sourceMap,
 					Hostname:          opts[keyHostname],
+					Warn: func(msg string, location *parser.Range) {
+						if i != 0 {
+							return
+						}
+						c.Warn(ctx, defVtx, msg, warnOpts(sourceMap, location))
+					},
 				})
 
 				if err != nil {
@@ -767,6 +779,29 @@ func scopeToSubDir(c *llb.State, fileop bool, dir string) *llb.State {
 	return &bc
 }
 
+func warnOpts(sm *llb.SourceMap, r *parser.Range) client.WarnOpts {
+	opts := client.WarnOpts{Level: 1}
+	if r == nil {
+		return opts
+	}
+	opts.SourceInfo = &pb.SourceInfo{
+		Data:       sm.Data,
+		Filename:   sm.Filename,
+		Definition: sm.Definition.ToPB(),
+	}
+	opts.Range = []*pb.Range{{
+		Start: pb.Position{
+			Line:      int32(r.Start.Line),
+			Character: int32(r.Start.Character),
+		},
+		End: pb.Position{
+			Line:      int32(r.End.Line),
+			Character: int32(r.End.Character),
+		},
+	}}
+	return opts
+}
+
 func wrapSource(err error, sm *llb.SourceMap, ranges []parser.Range) error {
 	if sm == nil {
 		return err

frontend/dockerfile/dockerfile2llb/convert.go

@@ -68,6 +68,7 @@ type ConvertOpt struct {
 	ContextLocalName  string
 	SourceMap         *llb.SourceMap
 	Hostname          string
+	Warn              func(msg string, location *parser.Range)
 }
 
 func Dockerfile2LLB(ctx context.Context, dt []byte, opt ConvertOpt) (*llb.State, *Image, error) {
@@ -91,6 +92,10 @@ func Dockerfile2LLB(ctx context.Context, dt []byte, opt ConvertOpt) (*llb.State,
 		return nil, nil, err
 	}
 
+	for _, w := range dockerfile.Warnings {
+		opt.Warn(w.Message, w.Location)
+	}
+
 	proxyEnv := proxyEnvFromBuildArgs(opt.BuildArgs)
 
 	stages, metaArgs, err := instructions.Parse(dockerfile.AST)

frontend/dockerfile/parser/parser.go

@@ -269,15 +269,25 @@ func newNodeFromLine(line string, d *directives, comments []string) (*Node, erro
 type Result struct {
 	AST         *Node
 	EscapeToken rune
-	Warnings    []string
+	Warnings    []Warning
+}
+
+type Warning struct {
+	Message  string
+	Location *Range
 }
 
 // PrintWarnings to the writer
 func (r *Result) PrintWarnings(out io.Writer) {
 	if len(r.Warnings) == 0 {
 		return
 	}
-	fmt.Fprintf(out, strings.Join(r.Warnings, "\n")+"\n")
+	for _, w := range r.Warnings {
+		fmt.Fprintf(out, "[WARNING]: %s\n", w.Message)
+	}
+	if len(r.Warnings) > 0 {
+		fmt.Fprintf(out, "[WARNING]: Empty continuation lines will become errors in a future release.\n")
+	}
 }
 
 // Parse reads lines from a Reader, parses the lines into an AST and returns
@@ -288,7 +298,7 @@ func Parse(rwc io.Reader) (*Result, error) {
 	root := &Node{StartLine: -1}
 	scanner := bufio.NewScanner(rwc)
 	scanner.Split(scanLines)
-	warnings := []string{}
+	warnings := []Warning{}
 	var comments []string
 
 	var err error
@@ -341,7 +351,10 @@ func Parse(rwc io.Reader) (*Result, error) {
 		}
 
 		if hasEmptyContinuationLine {
-			warnings = append(warnings, "[WARNING]: Empty continuation line found in:\n    "+line)
+			warnings = append(warnings, Warning{
+				Message:  "Empty continuation line found in: " + line,
+				Location: &Range{Start: Position{Line: currentLine}, End: Position{Line: currentLine}},
+			})
 		}
 
 		child, err := newNodeFromLine(line, d, comments)
@@ -384,10 +397,6 @@ func Parse(rwc io.Reader) (*Result, error) {
 		comments = nil
 	}
 
-	if len(warnings) > 0 {
-		warnings = append(warnings, "[WARNING]: Empty continuation lines will become errors in a future release.")
-	}
-
 	if root.StartLine < 0 {
 		return nil, withLocation(errors.New("file with no instructions"), currentLine, 0)
 	}