commands: build summary of warnings on build

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

commands/build.go

@@ -1,9 +1,11 @@
 package commands
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"strings"
@@ -22,7 +24,9 @@ import (
 	"github.com/docker/go-units"
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/session/auth/authprovider"
+	"github.com/moby/buildkit/solver/errdefs"
 	"github.com/moby/buildkit/util/appcontext"
+	"github.com/morikuni/aec"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -245,9 +249,51 @@ func buildTargets(ctx context.Context, dockerCli command.Cli, opts map[string]bu
 		}
 	}
 
+	printWarnings(os.Stderr, printer.Warnings(), progressMode)
+
 	return resp[defaultTargetName].ExporterResponse["containerimage.digest"], err
 }
 
+func printWarnings(w io.Writer, warnings []client.VertexWarning, mode string) {
+	if len(warnings) == 0 || mode == progress.PrinterModeQuiet {
+		return
+	}
+	fmt.Fprintf(w, "\n ")
+	sb := &bytes.Buffer{}
+	if len(warnings) == 1 {
+		fmt.Fprintf(sb, "1 warning found")
+	} else {
+		fmt.Fprintf(sb, "%d warnings found", len(warnings))
+	}
+	if logrus.GetLevel() < logrus.DebugLevel {
+		fmt.Fprintf(sb, " (use --debug to expand)")
+	}
+	fmt.Fprintf(sb, ":\n")
+	fmt.Fprint(w, aec.Apply(sb.String(), aec.YellowF))
+
+	for _, warn := range warnings {
+		fmt.Fprintf(w, " - %s\n", warn.Short)
+		if logrus.GetLevel() < logrus.DebugLevel {
+			continue
+		}
+		for _, d := range warn.Detail {
+			fmt.Fprintf(w, "%s\n", d)
+		}
+		if warn.URL != "" {
+			fmt.Fprintf(w, "More info: %s\n", warn.URL)
+		}
+		if warn.SourceInfo != nil && warn.Range != nil {
+			src := errdefs.Source{
+				Info:   warn.SourceInfo,
+				Ranges: warn.Range,
+			}
+			src.Print(w)
+		}
+		fmt.Fprintf(w, "\n")
+
+	}
+}
+
 func newBuildOptions() buildOptions {
 	ulimits := make(map[string]*units.Ulimit)
 	return buildOptions{